Treating Myopia

Technical Field

The invention relates to the treatment of myopia, particularly high myopia, where selective light delivery to one or more regions/areas within the equatorial peripheral part of the sclera part of the eye produces a therapeutic effect in tissues illuminated at those regions/areas by light delivered though the pupil, wherein the therapeutic effect is for example strengthening of the sclera biomechanics via light induced cross linking in the illuminated part of the equatorial peripheral part of the scleral tissue.

Background of the Invention

High myopia, or extreme short-sightedness, is an example of an eye condition which is a leading cause of low vision and blindness. Its prevalence is predicted to rise to afflict nearly 1 billion people by 2050, being 9.8% of the global population. Approximately seventy percent of those with high myopia will develop pathological complications.

The sclera is a viscoelastic structure that normally helps constrain the eyeball. High myopia is characterised by an excessively elongated eyeball accompanied by extreme thinning in the outer coat of the eye (the sclera) and is associated with the development of retinal detachment, lacquer cracks, ectatic outpouchings called staphyloma (staphyloma formation), myopic choroidal neovascularization and myopic macular degeneration (MMD). The sclera in high myopia shows an abnormal redistribution of the different types of collagen with an increase in small diameter collagen fibers. Overall loss of collagen eventually takes place. Myopic sclera also has an increased creep rate indicative of it being more elastic with reduced strength to support the eyeball wall. These pathologies are conventionally recognized to occur predominantly around the optic disk/optic nerve head and in the posterior pole where elongation dominates (i.e. centered on the long axis of the eyeball). It is believed that a less rigid biomaterial will be susceptible to the in vivo physiological forces it experiences, and although not directly proven, it is proposed that under interocular pressure (IOP) such a remodelled weakened structure will naturally elongate and potentially is less able to bear the IOP load. A reduction in rigidity is also likely to modify the stress on fibroblasts within the sclera. The associated biomechanical signals are also likely to alter the production and types of collagen synthesised.

Fortifying the posterior scleral wall for high myopia has a long history, initially beginning with the surgical attachment of grafts under the ocular muscles and/or application of substrates to the external wall of the sclera. The efficacy of these invasive approaches is very dependent on surgical skills and outcomes and safety are variable, with clear scar effects underlying the observed changes with external substrate application. More recently, there is interest in directly strengthening scleral structure from within, using collagen crosslinking approaches which are successfully used to stabilize corneal shape in humans. Since the dramatic changes in myopic sclera occur at the posterior pole where the pathology typically develops, crosslinking approaches propose directly strengthening the sclera at the posterior pole. To date, there is no approved crosslinking approach in humans.

Several crosslinking methods which have been proposed for scleral treatment of high myopia. Drugs such as glyceraldehyde, genipin and formaldehyde releasers (FARs) have been proposed and provide direct chemical crosslinking by a relatively simple injection, such as a sub-tenon’s injection behind the limbus and under the conjunctiva. However, a drawback of chemical crosslinking is that with current methods it is not possible to confine treatment to one or more small local areas due to spread of the reagent. Further it is difficult restrict/discriminate crosslinking from potentially affecting adjacent tissues which is an undesirable outcome for example in terms of safety. Further, the present inventors have demonstrated that when the entire posterior region of an eyeball is cross-linked to induce widespread scleral strengthening, the eyeball simply cannot expand posteriorly. Therefore, under increased IOP, undesirably the eyeball expands through the cornea, eventually bursting at the limbus. These observations lend to the likely need for only local and targeted regions of the sclera to be treated with crosslinking agents.

An alternative approach supporting restriction/selection of a local/confined treatment zone, proposes application of a solution of photoinitiator substance to a localized target region of the sclera using a subtenon’s or retrobulbar injection and subsequent localized activation by light.

For example, such an approach could be based on the original “Dresden protocol” as used for corneal crosslinking which involves the impregnation of the cornea (after abrasion of the central epithelium) with riboflavin which must then be activated by UVA light. Dextran is typically added to limit the depth of penetration and pulsed UVA protocols or leaving the epithelium intact can limit the potential photodamage from UVA light. However, as UVA light cannot reach the sclera indirectly through the pupil, such methods require direct light application applied to the posterior sclera region and therefore presents challenges with surgical access necessary and so safety. This is true for any photo initiator method dependent upon wavelengths that require external light delivery to the sclera. Typically, activating light is envisaged as being applied directly to a posterior region of the globe. In some embodiments, a fiber optic or similar light source is envisaged as integrated into the cross-linker photoinitiator delivery device. Such approaches require surgical access to the injection site and significant scar tissue likely occurs within the track left by any such light delivery devices.

A potentially less invasive method entails using photo initiators that can be activated by light entering via the pupil and with a wavelength able to traverse through the globe to penetrate the posterior sclera. The approach through the pupil potentially avoids the significant surgical requirement associated with direct light application. However, light flooding the whole pupil will flood the whole inner eye and all scleral regions which does not solve the problem of treatment of confined or localized areas within the eye.

Suitable photo initiators (including bacteriochlorophyll-derived photosensitisers) which respond to specific wavelengths can be used, including near infrared (NIR) light which is known to have relatively deep ocular penetration capacity and can reach the sclera. Cyanobacteria convert light photons into chemical energy through oxygenic photosynthesis and rely on chlorophyl pigments for photon capture. In low light conditions, chlorophylls that absorb in the red and far-red (NIR>P700) are important determinants of the trapping rate of excitation energy transfer in the Photosystem I core antenna in cyanobacteria. WST11 is an example of a synthetic bacteriochlorophyll-derived photoinitiator that generates a high yield of oxygen radicals upon NIR illumination that act as precursors facilitating tissue crosslinking. WST1 1 has been successfully used to crosslink the rabbit cornea or sclera using direct NIR illumination. In the case of scleral application of WST11 , light was not directed through the pupil and so the surgical access required to provide the light was invasive. This approach has been reported to provide effective scleral stiffening in the posterior pole when WST-1 1 was applied ex-vivo in enucleated rabbit eyes. A sub-tenon’s curved needle guide (and several variations of such) is proposed to be used to reach and deliver the photo initiator drug to the posterior pole, followed by irradiating the posterior eyeball through the pupil with NIR provided by a laser light source. Use of a laser may not avoid bathing the entire eye with light depending on the required laser power, necessitating an optical set up that would also be relatively complex and expensive. Given the limitation of existing methods of treating myopia by light induced crosslinking of scleral tissue, an object of one aspect of the invention is to provide one or more improved methods.

A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that the document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Statements of the Invention

The invention relates to methods of treating myopia which involving crosslinking one or more localised/discrete regions not around the optic nerve but in the peripheral sclera away from the optic nerve and in particular towards or in an equatorial peripheral part of the eye as defined herein, and preferably the outermost one or two layers of the sclera in the selected equatorial peripheral region. Such treatment can protect the eye from myopic progression. The proposed treatment area/region referred to herein as the equatorial peripheral part (or peripheral equatorial part) of the sclera which is within a circumferential region ranging from up to 60° posterior to the equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye, which in some embodiments may encompass a scleral region adjacent to the cornea at the limbus, or a sclera region adjacent to the edge of the optic disk. It will be understood that that the equatorial plane is located at the widest part of the eye. In other embodiments the treatment area is between 45° posterior to the equatorial plane of the eye to up to 20° anterior to the equatorial plane of the eye.

In some embodiments, the methods may prevent progression from myopia to high myopia, potentially reverse myopia, and/or prevent pathological consequences of high myopia. In some embodiments, the method involves an eye condition for example, a myopia such as high myopia, school myopia, high myopia, pathological myopia, progressive myopia or any other form of myopia, most preferably high myopia. In some embodiments, the outermost layer of the sclera comprises the outer 25% or less of the sclera thickness where it is believed crosslinking strengthening will have the greatest effect/benefit in the treatment of myopia. The outermost one or two layers of the sclera comprises the outer 50% or less of the sclera thickness. The appropriate location/cut off for the outermost layers area to be exclusively treated however can be determined using scanning acoustic microscopy (SAM) which measures biomechanical properties that are related to tissue microstructure and/or second-harmonic generation (SHG) microscopy, for example as described elsewhere herein.

The invention also extends to a device of the invention, when used to treat and/or prevent an eye condition by illumination and/or light activation of a selectively targeted region of an eye to be treated to produce a therapeutic effect at the selectively targeted region which is one or more areas/regions in the peripheral sclera area, preferably the equatorial peripheral sclera part of an eye to be treated. Preferably, the therapeutic effect arises from inducement of crosslinking in the illumined area/regions, and may involve one or more of: halting progression in deformational changes in eye shape that precede myopic pathology; alleviating fibre thinning in the equatorial or anterior sclera to prevent fibre changes at the posterior pole; increasing the local bulk modulus of sclera at or near the equatorial peripheral region of the eye, particularly the outermost layers of the sclera at the equatorial peripheral region of the eye, particularly by light active protein/collagen crosslinking; preventing areas around the optic nerve ballooning outwards; preventing staphyloma forming around margins of the optic disc or elsewhere; preventing an increase in small diameter collagen fibres/use to preserve normal distribution of collagen types in sclera; preventing collagen loss in sclera. In a first aspect, the invention provides a light delivery device to be worn on a cornea in front of a pupil of a myopic eye to be treated by light activated scleral tissue cross linking, the device comprising: an opaque contact lens wearable on the cornea in front of at least the pupil of the eye and provided with one or more light guide apparatus comprising a light exit (preferably a geometrically shaped light funnel exit) and a geometrically shaped light entrance (preferably a funnel shaped entrance) to an elongate linear non reflective light path that internally directs light received at the entrance of the light path through the pupil to illuminate one or more localised/discrete internal regions in an equatorial peripheral part of sclera of the eye with a confined light spread beam of substantially collimated light that activates crosslinking at the illuminated regions of the eye pretreated with a light activatable crosslinker, wherein the light guide apparatus is opaque except for the light path, the exit of which interfaces with a light transparent region on a convex surface of the contact lens in a pupil region at an angle of from 5° to 85° to the optical axis of the contact lens, and wherein received light exits the light path as a confined light spread beam of substantially collimated light which traverses the convex surface of the light transparent region of the contact lens and is refracted beyond the interface by optical surfaces of the eye to direct the confined light spread beam to selectively and exclusively illuminate the scleral tissue in localised/discrete internal regions to be crosslinked in a equatorial peripheral region of the sclera defined as a circumferential region ranging from up to 60° posterior to an equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye to be treated, wherein light entrance has a width w, and the light path has a depth d between the entrance and the exit of the light path, with a width w to depth d ratio (w/d) of 1 :2 or greater, preferably 1 :5 or greater, more preferably 1 :10 or greater.

In a second aspect, the invention provides a light delivery a light delivery device to be worn on a cornea in front of a pupil of a myopic eye to be treated by light activated scleral tissue cross linking, by light activated scleral tissue cross linking, the device comprising: an opaque contact lens wearable on the cornea in front of at least the pupil of the eye and provided with one or more light guide apparatus comprising a light exit (preferably a geometrically shaped light funnel exit) and a geometrically shaped light entrance (preferably a funnel shaped entrance) to an elongate linear non reflective light path that internally directs light received at the entrance of the light path and projects it through the pupil to illuminate one or more localised/discrete internal regions within an equatorial peripheral part of sclera of the eye with a confined light spread beam of substantially collimated light that activates crosslinking at the illuminated regions of the eye pretreated with a light activatable crosslinker, wherein the light guide apparatus is opaque except for the light path, the exit of which interfaces with a light transparent region on a convex surface of the contact lens in a pupil region at an angle of from 5° to 85° to an optical axis of the contact lens, and wherein received light exits the light path as a confined light spread beam of substantially collimated light which traverses a convex surface of the light transparent region of the lens and is refracted beyond the interface by optical surfaces of the eye to direct the confined light spread beam to selectively and exclusively illuminate the scleral tissue in localised/discrete internal regions to be crosslinked in a equatorial peripheral region of the sclera defined as a circumferential region ranging from up to 60° posterior to an equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye to be treated, wherein the light path has hollow cone shape with the light entrance at a base of the hollow cone in the form of part of or the whole circumference of a circle or an oval, wherein the light path has a constant internal width w along the light path and a light path depth d between the entrance and the exit of the light path, with a width w to depth d ratio (w/d) of 1 :2 or greater, preferably 1 :5 or greater, more preferably 1 :10 or greater, and wherein light entering the circumference entrance produces a substantially ring shaped light spread beam in the equatorial peripheral region of the sclera.

It will be understood that constant internal width w along the light path corresponds to the wall thickness of a hollow cone. It will be further understood that the circumference entrance and width thereof is in the form of an annulus of width w and circumference length c.

Suitably, the hollow cone shape is a hollow frustoconical cone shape, wherein the light exit is at the truncated apex of the cone such that the truncated apex interfaces with the light transparent region on the convex surface of the contact lens.

Suitably, the hollow frustoconical cone shape of the light path is a hollow angled frustoconical cone shape, preferably a right angled hollow frustoconical cone shape or an oblique angled hollowed frustoconical cone shape.

Suitably, the hollow cone shape is a hollow circular cone shape or a hollow oval cone shape.

In this embodiment, structurally, the device may have at least one inner and an outer cone structure mounted onto the convex surface of the contact lens at or near the light transparent region so that the exit of the light path formed interfaces at the light transparent region.

Desirably, the hollow cone shape of the light path may be formed from an offset overlay of a pair of cone structures, wherein the apex region or truncated apex region of each are mounted onto the contact lens, such that the exit of the light path interfaces with the light transparent region on the convex surface of the contact lens in a pupil region at an angle of from 5° to 85° to the optical axis of the contact lens. Desirably, a width of light entrance of the light path is determined by the space formed as a result of the offset overlay of the pair of cone structures.

Alternatively, the inner cone may have a smaller base radius cone than the base radius of the outer cone, wherein the difference in base radii corresponds to the width w of the hollow cone shaped light path so formed.

The depth d of the light path is determined by the length of the hollow cone or hollow frustoconical cone.

The width of the light entrance (e.g. funnel) and/or and light exit (e.g. light funnel exit) the constant internal width w along the light path may be adjusted by variation in the size of the offset between the cone structures or adjusting the radii of the bases of the inner or outer cones. It will be understood that adjustment of the width of the light entrance (e.g. funnel entrance and exit and constant internal width there between) controls the width of the substantially ring shaped light spread beam in the targeted equatorial peripheral region of the sclera.

Preferably, the depth d between the entrance and the exit of the light path provides a desired depth to the light path. In some embodiments, the defined distance d ranges from 1 to 20 mm. In other embodiments, the defined distance d ranges from 3 mm to 18 mm, 5 mm to 15 mm, 7.5 mm to 12.5 mm. In some embodiments, the defined distance d is at least 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm. In some embodiments, defined distances of 5mm or greater are preferred. Preferably, the width w and the depth d of the light path operatively configured to provide a desired width and/or other dimensions to the illuminating confined light spread beam of collimated light in the targeted equatorial peripheral region of the sclera.

In some embodiments, the angled cone shape of the light path is an uninterrupted cone shape that produces an uninterrupted ring shaped or banded light spread beam in the targeted equatorial peripheral region of the sclera.

In other embodiments, the angled cone shape of the light path is an interrupted cone shape, which can be segmented into a desired arrangement having any desired number of segments. For example, various fractions of the cone that are possible include a half cone shape which produces a semi-circular or semi oval ring shaped light spread beam; two distinct half cone shapes which produce two distinct semi-circular or semi oval half ring shaped light spread beams; thirds segments which produce three distinct curved shaped light spread beams; quarter segments (quadrants) which produce four distinct curved shaped light spread beams, and so on.

In a third aspect, the invention provides a light delivery device to be worn on a cornea in front of a pupil of a myopic eye to be treated by light activated scleral tissue cross linking, the device comprising: an opaque contact lens wearable on the cornea in front of at least the pupil of the eye and provided with a plurality of light guide apparatus, each comprising a light exit (preferably a geometrically shaped light funnel exit) and a geometrically shaped light entrance (preferably a funnel shaped entrance) to an elongate linear non reflective light path that internally directs light received at the entrance of the light path through the pupil to illuminate multiple localised/discrete internal regions in an equatorial peripheral part of sclera of the eye with a confined light spread beam of substantially collimated light that activates crosslinking at the illuminated regions of the eye pretreated with a light activatable crosslinker, wherein each of the plurality of light guide apparatus is opaque except for the light path, the exit of which interfaces with a light transparent region on a convex surface of the contact lens in a pupil region at an angle of from 5° to 85° to the optical axis of the contact lens, and wherein received light exits each light path as a confined light spread beam of substantially collimated light which traverses the convex surface of the light transparent region of the contact lens and is refracted beyond the interface by optical surfaces of the eye to direct the confined light spread beam to selectively and exclusively illuminate the scleral tissue in localised/discrete internal regions to be crosslinked in a equatorial peripheral region of the sclera defined as a circumferential region ranging from up to 60° posterior to an equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye to be treated, wherein light entrance of each light path has a width w, and the light path has a depth d between the entrance and the exit of the light path, with a width w to depth d ratio (w/d) of 1 :2 or greater, preferably 1 :5 or greater, more preferably 1 :10 or greater, and wherein each of the plurality of light guide apparatus are position on the lens relative to each other to exclusively target the multiple localised/discrete internal regions in the equatorial peripheral part of sclera of the eye.

Desirably, the plurality of light guide apparatus comprises 4 or more distinct light guide apparatus, preferably 5 or more, 6 or more, 7 or more, 8 or more _a 9 or more _a 10 or more, 11 or more, 12 or more distinct light guide apparatus. Desirably, the plurality of light guide apparatus are positioned in a substantially ring configuration or a substantially annular configuration on the lens, such that the exit of each light path interfaces with the lens in a region adjacent the pupil when the device is worn.

Suitably, the exit of the light path interfaces with the convex surface of light transparent region of the lens at an angle of from 10° to 85°, 15° to 85°, 20° to 85°, 25° to 85°, 30° to 85°, 35° to 85°, 40° to 85°, 45° to 85°, or 50° to 85° to the optical axis of the contact lens. In some embodiments, an angle of 35° to 85° to an optical axis of the contact lens is preferred.

In a fourth aspect, the invention provides a method of treating a myopia, preventing a myopia or halting myopia progression by light induced biomechanical strengthening of sclera tissue in one or more localised/discrete regions in an equatorial peripheral part of an eye to be treated, comprising the step of:

- crosslinking scleral tissue in the one or more localised/discrete regions within the equatorial peripheral part of the sclera of the eye to be treated by internally delivering one or more confined light spread beams of light through a pupil of the eye to selectively and exclusively illuminate and crosslink tissue in the illuminated one or more localised/discrete regions only, wherein the illuminated tissue has been pre-treated with a crosslinking agent subsequently activated by the illuminating light entering the eye through the pupil.

In a fifth aspect, the invention provides a use of a light delivery device to be worn on an eye to internally deliver one or more confined light spread beams of light through a pupil of the eye to tissue to be crosslinked in one or more localised/discrete regions in an equatorial peripheral part of the sclera part of an eye to be treated, the device according to the first or second aspects.

In a sixth aspect, the invention provides a use of a light delivery device to be worn on an eye to internally deliver one or more confined light spread beams of light through a pupil of the eye to tissue to be crosslinked in the equatorial peripheral part of the sclera of the eye which is the circumferential region ranging from up to 60° posterior to the equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye, the device as defined in the first or second aspect.

Brief Description of the Figures

Embodiments of the invention will herein be illustrated by way of example only with reference to the accompanying drawings in which:

Figure 1 illustrates (a) H&E stained histology image showing superior region of posterior sclera of a guinea pig eye. The corresponding Second Harmonic Generation (SHG) image was manually co-registered and is overlayed. (POS = posterior, ANT = anterior, ONH = optic nerve head), (b) Scanning Acoustic Microscopy (SAM) images obtained using a 250-MHz ultrasonic transducer were processed to produce amplitude images of the adjacent tissue section in (a). ROIs (red boxes) start at the centre of the ONH and are 200pm long, (c) Magnified section of the SHG image in (a). Yellow curves indicate the boundaries of the scleral layers, each comprising 25% of the scleral thickness. Yellow arrows identify the interior and exterior edges of the sclera, (d) Magnified section of SAM amplitude image and similar to (c), whereby red curves indicate boundaries of the pre-defined scleral layers in the SAM amplitude image.

Figure 2 illustrates an example map of bulk modulus values (K) using the SAM system and SHG image with exclusions masks applied, (K) is related to the shear modulus and measures the resistance of a material to volumetric loads; a larger value of K indicates a stiffer material. Both images and magnified sections correspond to approximately the same section of sclera within adjacent tissue sections, (a) K map estimated from radio frequency (RF) echo data. Boundaries of the pre-defined scleral layers are superimposed in red. (b) A subset of collagen fibers identified in CurveAlign overlayed on corresponding SHG image.

Figure 3 illustrates box plots of mean acoustic parameter estimates by layer in myopic and control guinea pig eyes. Dot overlay shows individual ROI samples. Overbars indicate statistical significance of independent samples t-tests comparing parameter values between control and myopic eyes, (a) Bulk modulus (K), (b) acoustic attenuation (p), and (c) mass density (a). (* : 0.01 < p < 0.05; ** : 0.001 < p < 0.01 ; *** : 0.0001 < p < 0.001 ; **** : p < 0.0001).

Figure 4 illustrates box plots of mean collagen fiber features by layer in myopic and control guinea pig eyes. Dot overlay shows individual ROI samples. Overbars indicate statistical significance of independent samples t-tests comparing parameter values between control and myopic eyes, (a) Fiber length,

(b) alignment, (c) straightness, (d) width, and (e) number density (* : 0.01 < p < 0.05; ** : 0.001 < p < 0.01 ; *** : 0.0001 < p < 0.001 ; **** : p < 0.0001).

Figure 5 illustrates differences between control and myopic guinea pig eyes for acoustic parameters as a function of eccentricity (distance from optic nerve head (ONH) midline). Each point represents the mean value from all four layers within a ROI across all control or myopic eyes. Solid lines represent the line of best fit. (a) Bulk modulus, (b) mass density, and (c) acoustic attenuation.

Figure 6 illustrates scatterplots comparing control and myopic guinea pig eyes for various collagen fiber features as a function of eccentricity (distance from optic nerve head (ONH) midline). Each point represents the mean value from all four layers within a ROI across all control or myopic eyes. Solid lines represent the line of best fit. (a) Fiber length, (b), alignment, (c) number density, (d) width, and (e) straightness.

Figure 7 illustrates the effect of myopia on different layers within the sclera. Scatterplots comparing bulk modulus and collagen fiber width estimated within each scleral layer in control and myopic guinea pig eyes are shown. Points represent the mean parameter value across all control or myopic eyes within each layer 1 -4 of each ROI. Lines represent the best linear fit. (a) Bulk modulus and (b) fiber width in control eyes.

(c) Bulk modulus and (d) fiber width in myopic eyes. In untreated eyes, bulk modulus (K) increases in Layer 1 (the outermost layer of the sclera) with increasing eccentricity from the optic nerve head (ONH) (see (a)). This implies that the sclera is normally stiffer at the equator and more elastic around the optic nerve. This normal variation in Layer 1 disappears in myopic eyes (see (b)). Fiber width is constant in normal eyes but decreases with increasing eccentricity from the optic nerve in all scleral layers in myopic eyes (compare ((b) and (d)). This shows that myopia causes scleral collagen fibers to thin in the periphery throughout the scleral layers.

Figure 8 illustrates representative correlations between various acoustic parameters with spatially co-registered collagen fiber features. Each point represents the parameters estimated within an ROI corresponding to the same section of sclera in both images. Lines represent linear fits. Plots show parameters for the average of layers 1 -3 versus layer 4 for correlations between (a) number density and acoustic attenuation (a); (b) fiber length and bulk modulus (K); and (c) fiber alignment and mass density (p).

Figure 9 illustrates a young guinea pig eye suspended upright in space and imaged from underneath with the sclera peeled back. The young guinea pig eye is able to self-support and maintain its shape from the remaining choroidal and retinal layers, despite removal of the sclera. This demonstrates that the sclera does not constrain the shape of the eyeball alone. Figure 10 illustrates A. young guinea pig eyes subjected to increased intraocular pressure expand anteriorly (at the front of the eye), ultimately bursting at the weakest point, which is the limbus through which the crystalline lens is expelled (white arrow). This shows that under increased intraocular pressure, a normal eyeball does not necessarily elongate posteriorly. B. Eyes which are cross-linked only in the posterior region of the eye, also expand anteriorly, but much more slowly than untreated eyes, showing that posterior crosslinking protects the eye from anterior and posterior expansion.

Figure 11 illustrates eye shape during the development of Myopia in young guinea pigs commences with changes in the peripheral region of the globe. A. Difference between the Myopic eye and the Control eye in the length of the Vitreous Chamber after different periods of form deprivation (FD). The eye expands around the optic nerve head (red arrow), while the periphery (for example at 30-60 degrees in nasal retina) initially shrinks prior to eventually expanding. B. Central cut through a Control eye (left) and myopic eye (right) from the same animal. Double ended red arrow shows the location of the optic nerve. The insert shows that myopia causes a doubling in the area around the optic nerve. The white line on the control eye in B. shows where the vitreous chamber depth was measured (example line corresponds to 60 degrees in nasal retina in A).

Figure 12 shows components of the eye and comparison between human and guinea pig eyes in which exemplary devices were tested. A. average dimensions of sclera and cornea of the human eye. B. Location terminology. C. Chambers of the eye. D. Standard components of the eye. E. Ray trace on-axis through a 30 day old guinea pig eye. F Central ray trace through a human eye at a similar stage of development and at the same scale as in E. The extent of the peripheral equatorial region is indicated on both E and F (between the angled blue lines).

Figure 13 illustrates an empirical test of exemplary device with a single pipe providing a localised and well defined spot of light on the equator of an enucleated guinea pig eye. (A) Illustrates a close up of a guinea pig eye wearing the device. The white tissue is the conjunctiva which lies external to the sclera. (B) Raytracing of any coherent light (all light rays are phase synchronized with each other) that traverses through the opaque pipe/light guide apparatus to selectively reach a discrete/localised area in the equatorial peripheral part of the sclera region (blue lines). (C) Diagram of an example of a single pipe device in situ on an eye; and (D) Image of the light spot taken from underneath the ocular globe, showing the posterior scleral surface. The blue arrow (left most solid line) is at the limbus, while the dashed line and arrow represent the equator, and the yellow arrow (right most arrow) shows the discrete circular spot of light obtained from stimulation with white light provided through the device. The selectively targeted localised region lies just below the equator. The image also demonstrates the precision with which a narrow beam of light can selectively illuminate a very specific part of the eye;

Figure 14 illustrates a device scaled for the guinea pig eye and having multiple (12 in example A-D) light pipes/light guide apparatus disposed on the contact surface in a configuration which is intended to stimulate one more discrete regions of the peripheral sclera generally circumferentially disposed all around the equatorial region by providing individualised illuminated light areas. Note that discrete spots will be provided along the entire eye circumference. (A) is a view from above, (B) is a view from below, (C) and (D) show a schematic of the device in situ on a guinea pig eye. (E) and (F) illustrate a variation of the device scaled for the guinea pig eye designed to provide illumination in the equatorial peripheral region in the form of an uninterrupted ring or half ring of illumination around the entire circumference of the equatorial region of the eye to be treated. Note that the light source(s) are not shown but lie behind or at the light pipe/guide opening(s) (for example see the red line in (B)).

Figure 15 illustrates exemplary devices scaled forthe human eye. (A) Model of a human eye without any device showing the boundary between the cornea and sclera. (B) - (C) Device designed to provide illumination in the form of an uninterrupted ring of illumination around the entire circumference of the equatorial region of the eye to be treated. Except for the circular light path, the device covers the cornea (a) and may also occlude any exposed sclera (b) to exclude any stray light from penetrating the eye; Light enters the device in the circular slit (c). (D) - (F) Different views of an example variation in which only a portion of the equatorial peripheral region of a human eye is stimulated with light (e.g., here a semicircular region of illumination).

Figure 16 is Table 1 which reports mean acoustic and collagen fiber parameters values ± SEM within each layer of control and myopic eyes. Stated p-values were computed from an independent samples t-test comparing the parameter values of control and myopic eyes. Bold type indicates statistical significance (p < 0.05); and

Figure 17 is Table 2, which reports slope, R ² , and p-values computed from linear regression analyses comparing acoustic parameters and collagen fiber features estimated from co-registered tissue sections. Parameters were averaged over all layers, over layers 1 -3, or within layer 4.

Definitions

As uses herein, the “treatment of myopia” means any direct treatment of the sclera that strengthen its biomechanical properties or stop the conversion to smaller diameter collagen fibers in the outermost sclera. Herein this includes crosslinking treatments whether light activated within or beyond the visible range. It is not directed at lens or spectacle type treatments which by their nature may influence any part of the eye.

“Outer layers of the sclera” means the layer of the sclera that is furthest away from the choroid. The present inventors have identified the presence of four scleral layers based on now appreciated variation in biomechanical properties. Layer 1 is the outermost layer of the sclera (within it) where it has been found that the biomechanical properties are most affected by myopia, (although all 4 layers are partially affected). Layer 4 aligns with the innermost layer of the sclera (called the lamina fusca), which is separated from the underlying choroid by a thin space known as suprachoroidal space. The inventors have found that the myopic eyes failed to show the normal greater relative mass density in the lamina fusca compared to the overlying scleral layers.

Detailed description of the invention

The invention relates to a new method of treating and/or preventing a myopia in an eye of a subject in need of treatment. The myopia maybe high myopia, school myopia, high myopia, pathological myopia, progressive myopia or any other form of myopia. In preferred embodiments, the myopia treated is preferably high myopia.

The method comprises delivering or directing one or more confined (e.g., narrow, small) beams (preferably in the form of ring shape or half ring etc. shapes), that is, individualised beam(s) of light internally to tissue in the eye to be treated through a pupil of the eye such that the beams of light illuminate one or more localised and/or discrete areas/regions of sclera in the equatorial peripheral region or part of the eye, whereby the light initiates crosslinking of photoinitiator crosslinking reagents provided to the tissues in advance of the illumination step. The equatorial peripheral part of the sclera is the part of the eye in the circumferential region ranging from up to 60° posterior to the equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye. The inventors have selected one or more areas/regions in this part of the eye as a target for crosslinking on the basis of the findings presented in Figure 7a and Figure 7c (see the blue dots representing Layer 1 ) where it is observed that the results for myopic eyes increasingly deviate from control the further away from the optic nerve (located at position zero on the x-axis). In guinea pig eyes, the considered properties were examined at distances up to 3.5 mm or 4.5 mm from the optic nerve in these small mammalian eyes, which is considered to be the part approximately just posterior to the equator. This part of the eye is where the maximum effect was seen (i.e., where the fiber width is thinnest (in ALL layers 1 ,2,3 and 4) and sclera strength (bulk modulus) is weakest in layers 1 and 2 in progressing myopic eyes relative to control eyes. While parts beyond 3.5mm and 4.5mm from the optic nerve was not considered, the line fitting for the blue dots (and orange triangles in Figure 7) suggests this thinning and weaker biomechanical properties in myopic eyes may be even greater at even greater distances from the optic nerve, that is, in areas closer to and at the equator including the region anterior to the equator. The preferred treatment age for a human eye is from about 10 to about 25 years of age. Given the distances considered (3.5 and 4.5mm) are only relevant to the guinea pig eye (30 days old) and will be much greater in, e.g., a 15 year-old human eye (approximately 23.5 mm long v guinea pig eye which is only 8.3 mm long at an equivalent age), the inventors have extrapolated the guinea pig results to parts of a human eye corresponding to the equatorial peripheral sclera is the circumferential region ranging from up to 60 ° posterior to the equatorial plane of the eye to up to 30 ° anterior to the equatorial plane of the eye. It will be understood that that the equatorial plane is located at the widest part of the eye.

Preferably, the light is near infra-red light sufficient to pass through the pupil and to reach the targeted areas/regions of tissue at an intensity that is sufficient to activate a photo initiator. In some embodiments, the light is not blue light. In preferred embodiments, the light is provided by one or more LED light sources. Preferably the LED light is not collimated or may be minimally collimated, though in some embodiments collimated light can be used.

The one or more beams of delivered light are provided in a manner that exclusively illuminates one or more selectively targeted localised regions of the equatorial peripheral part of the sclera of the eye to be treated to result in a therapeutic effect at the selectively targeted localised region of the eye. It will be understood that the light is allowed to illuminate the selectively targeted localised region of the eye for a period of time sufficient to produce the desired therapeutic effect. There have been no previous reports of treatment of myopia by scleral tissue crosslinking via delivery of light (preferably near infra-red light) directly through the pupil such that incident light is provided directly onto the inner tissues of the eye in one or more localised areas/regions of the equatorial peripheral part of the sclera where such tissues have been pretreated with a crosslinkable photoinitiator drug or reagent.

During treatment of a myopia, particularly high myopia, the selectively targeted region of the eye is one or more discreet/localised areas in the equatorial region, preferably a particular frontal plane passing anterior, on or posterior to the equator of the particular eye globe to be treated (see Figure 12B, F). Preferably, however, one or more discreet/localised areas in the equatorial region are preferably not selected such that the entire circumference of the equatorial peripheral part of the sclera is crosslinked.

Therefore, the inventors propose that the treatment location for those at risk of developing myopias, and particularly high myopia pathologies, should selectively target one or more discreet/localised areas in the equatorial peripheral sclera. In particular, the treatment location in preferred embodiments is specifically the outer layers of the equatorial peripheral scleral regions of the eye. In some embodiments, only the outer most layer of the sclera is targeted for crosslinking, as this location will benefit most from the biomechanical strengthening treatment described herein.

The anterior focused approach involving light delivery directly through the pupil is both technically feasible, located towards the front of the eyeball so more easily accessible than existing/proposed posterior pole treatments. Further suitably the selected one or more discrete regions/areas of the equatorial peripheral part of the scleral region are distant from the optic nerve (and located between the macular and optic disk) which means it is a safer target area than the posterior pole region currently considered as the likely/optimal target for crosslinking to treat myopia. These areas can be pretreated by being provided with photo initiator based crosslinking agent, e.g., though sub tenons injection with a short, curved needle. The inventors also believe that in the human eye, where the macula is located 17 degrees temporal to the optic disc, the crosslinking treatments now possible using the methods of the invention will readily avoid the disc and macula.

Suitably, the beam(s) result in illumination of the one or more discrete areas/regions in the equatorial peripheral part of the sclera. The areas can be in the form of a discrete or isolated ring or rings, a discrete or isolated stripe or stripes, or a discrete or isolated spot or spots of the tissue in the equatorial peripheral part of the sclera. In all cases, the areas are small in comparison to the whole eye dimensions. Preferably, the light region, area or spot may have a width, length and/or diameter ranging from 0.5 mm to 5 mm. It will be understood that the beam results in illumination at the targeted localised area/region as an illuminated light region, area or spot may have a width, length and/or diameter ranging from 0.5 mm to 5 mm, preferably 0.5 mm to 2.5 mm, more preferably from 0.5 mm to 1 .5 mm. Such dimensions give rise to the small, localised or confined regions/areas as they are described herein. As explained above, in some embodiments, it is preferred not to target the entire external circumference of the equatorial peripheral part of the sclera at a single time. In one embodiment described herein targeting the entire internal circumference of the equatorial peripheral part of the sclera at a single time is preferred.

It will be understood that preferably, just before application of the light to the eye, the one or more selectively targeted localised and/or discrete regions of the equatorial peripheral part of the sclera are pretreated with a crosslinking agent such that light illuminating those regions induces a therapeutically effective degree of protein crosslinking in targeted localised regions of the equatorial peripheral part of the sclera. The agent can be a protein crosslinking agent, for example, a collagen crosslinking agent, which is a photo initiator compounds activatable by the light provided internally to the eye. Activatable by light means, light of sufficient intensity and/or wavelength can initiate one or more chemical reactions involving the agent and protein/collagen which results in formation of crosslinking in the protein.

It will be understood that the light used is a type of light that is known to produce the particularly desired therapeutic effect on the tissue in the illuminated region of the eye, that is, the tissue in one or more areas of the equatorial peripheral part of the sclera. For example, near infra-red (NIR) light when directed through the pupil can reach the equatorial peripheral part of the sclera in an amount that is suitable for inducing crosslinking at an area illuminated, where the targeted areas of the eye have been pre-treated with a protein crosslinking agent which is activatable by light, most preferably by NIR light.

In preferred embodiments, the crosslinking agent is a crosslinking drug or reagent which is activatable upon illumination with light, preferably with NIR light, such as those based on chlorophylls containing cyanobacterium and their derivatives. The equatorial peripheral part of the sclera of the eye is made up of tissue comprising various proteins and biomolecules which comprise crosslinkable functional groups. In some embodiments, crosslinking is induced in protein which includes at least collagen protein.

Preferably, the one or more selectively targeted localised regions of the equatorial peripheral part of the sclera are one or more outer layers of the equatorial peripheral part of the sclera which are furthest away from the eye’s choroid. Suitably, a preferred method only involves crosslinking in the outermost layer of the targeted equatorial peripheral part of the sclera. The crosslinking is caused via internal access of light to internal parts of the eye however.

Preferably, in the method of the invention, protein crosslinking (induced by delivery of suitable light illumination to the desired equatorial peripheral part of the scleral region which has been pretreated with a suitable crosslinking agent) at the targeted region produced induces one or more therapeutic effects at the targeted region and/or within the eye more generally, as follows:

- halting progression in deformational changes in eye shape that precede myopic pathology;

- alleviating collagen fiber thinning in the anterior sclera to prevent collagen fiber changes at the posterior pole;

- increasing the local bulk modulus of sclera at an equatorial peripheral region of the eye, particularly the outermost layers of the sclera at the equatorial peripheral region of the eye, particularly by light activated protein/collagen crosslinking;

- preventing areas around the optic nerve ballooning outwards;

- preventing staphyloma forming around margins of the optic disk or elsewhere;

- preventing an increase in small diameter collagen fibres;

- preserving normal distribution of collagen types in sclera; and/or

- preventing collagen loss in sclera.

Thus the inventors proposed that during development of myopia, remodelling of the sclera is actually initiated in the periphery (towards the anterior sclera) rather than at the posterior pole. The inventors propose herein that the treatment location for those at risk of developing high myopia pathologies should target the peripheral sclera, and specifically the outer layers of the sclera in the equatorial peripheral part of the scleral region. This approach is both technically feasible, located towards the front of the eyeball so more easily accessible and is distant from the optic nerve so relatively safe.

In one particular aspect, the invention provides a method of treating and/or preventing myopia by delivery of light to one or more localised or discrete areas/regions in the equatorial peripheral part of the scleral region, particularly through the pupil of an eye, preferably with NIR light, to produce a light induced localised therapeutic effect, that is indication of crosslinking in collagen in the area. The method involves directing light from a light source directly through a cornea of the eye to be treated and allowing the directed light to form one or more localised light spots or areas or regions on the eye at the desired targeted area/areas of interest. The light is then allowed to contact the targeted equatorial peripheral part of the scleral tissue for a period of time sufficient to result in a therapeutic effect at the area of the light spots.

Desirably, the eye has been pretreated with a drug or a reagent prior administered to the eye to be treated, preferably a crosslinking drug or reagent which is light activatable by light provided to the targeted localized region. On activation with suitable light the crosslinking drug or reagent induces crosslinking in the biomolecule present in the tissue at the region contacted by light. Desirably, crosslinking is confined to the precise area(s) contacted by the illuminating light. It will be understood that the light reaching the targeted tissue will be of a suitable energy to activate the crosslinking drug or reagent used. The energy of the light reaching the light spot depends on parameters including the intensity/luminous flux of the light emitted from a suitable light source reaching the target region, which is controllable by the voltage and/or current applied to the light source, the frequency of the light emitted, the wavelength of the light emitted from the light source, and the amount of stimulation time. These parameters can also be controlled to ensure the light is delivered to only the outermost scleral layers where most benefit will be derived from the biomechanical strengthening which occurs from the method of the invention.

The invention also provides a device which can selectively target with great precision the one or more localised or discrete areas, spots or regions of the eye in the equatorial peripheral part of the scleral regions while not needing to rely on a laser or otherwise collimated light source or without the need for the invasive surgical placement of waveguides externally around the eyeball in a subject to be treated. Since laser light is not required, there is less risk of damage or thermal damage to ocular tissues of both patient and operator compared to LED light stimulation. While the device can be configured to selectively deliver light of any type (wavelength, energy, intensity, etc.) preferably the device is used to deliver a narrow/confined beam or light spot of collimated light and/or coherent light to any one or more targeted localized regions of the equatorial peripheral part of the sclera of eye to be treated, preferably as ring or band shaped beams or portions of a ring shaped or band shaped ring. The targeted localized regions selected for selective light delivery may be any desired one or more localized regions of the equatorial peripheral part of the sclera region. In preferred embodiments, the sclera around the equatorial peripheral sclera are targeted, for example, in the treatment and/or prevention of a myopia, such as high myopia. Other areas of the eye are not treated.

Thus described herein is a light delivery device to be worn on the front of the eye (covering the cornea and exposed anterior sclera not destinated for treatment) and projecting light into a pupil of a myopic eye to be treated by light activated scleral tissue cross linking, the device comprising: an opaque contact lens mask wearable on the anterior eye and provided with one or more light guide apparatus. In one embodiment, the device comprises an opaque contact lens worn on the eye with one or more opaque light guide apparatus (e.g., pipe, tunnel or funnel or angled cone) attached to the contact lens mask that restricts light passing through the device (when worn) to that entering and exiting the light pipe. The contact lens mask may also be extended to restrict light from entering the eye through any exposed peripheral scleral regions not destinated to be treated. The one or more light guide apparatus comprises an exit and a geometrically shaped entrance to an elongate linear non reflective light path that internally directs light received at the entrance through the pupil to illuminate one or more localised/discrete internal regions within an equatorial peripheral part of sclera of the eye with a confined light spread beam of substantially collimated light that activates crosslinking at the illuminated regions of the eye pretreated with a light activatable crosslinker,

Suitably, the light guide apparatus is opaque except for the light path exit (e.g. funnel exit) which interfaces with a light transparent region of a convex surface of the contact lens in a pupil region at an angle of from 5° to 85° to an optical axis of the contact lens. In some embodiments, the interface contact angle is from 20° to 85° to the optical axis of the contact lens.

Desirably, wherein received light exits the restricted elongate linear light path as the confined light spread beam of collimated light which traverses a convex surface of the light transparent region of the contact lens and is refracted beyond the interface by optical surfaces of the eye to direct the beam to selectively and exclusively illuminate the internal scleral tissue to be crosslinked in a equatorial peripheral region of the scleral defined within a circumferential region ranging from up to 60° posterior to an equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye to be treated.

The collimated nature of the light beam exiting the light path and passing through the contact lens means the beam is narrow/confined as described above. It has the advantage that it is attached to the cornea and moves with eye movements thus eliminating the effect of unwanted movements and eliminates the need for a laser alignment system and can be used in non-cooperative patients such as children.

Advantageously, the proposed light path system allows the location of the stimulation area to be set to a defined diameter and at a specific predefined position to ensure the light is exclusively delivered to one or more areas/regions in the equatorial peripheral part of the sclera as described above. This involves specification of: the position and angle of the light path exit (e.g. funnel exit) relative to the centre of the pupil; the pipe diameter (or funnel entrance dimensions), angle and depth; the path (or funnel) entrance breadth and length; the curvature of the concave surface of the lens where it interfaces with the exit of the light path; and light source brightness and availability of collimated or LED light to transverse through the path to impinge perpendicular to the cornea at the base/exit of the path.

Preferably, the elongated linear light path has an inner cross-section shape and dimensions which are operatively configured together with the depth of the elongate linear light path to provide a desired shape and dimensions to the illuminating confined light spread beam of collimated light.

Preferably, the elongated linear light path has a constant inner cross-section shape with constant length and breadth dimensions along an entire depth of the elongated linear light path spanning from the entrance to the exit of the light path.

Preferably, the geometrically shaped entrance has a breadth that determines the breadth (shortest dimension) of the light spread beam and a length that determines the length (longest dimension) of the light spread beam.

Preferably, the geometrically shaped entrance to the elongated linear light path has a 2D (planar) geometrical shape such as a circle of radius r and diameter 2r; a square of length I x breadth b, wherein I and b are the same; a rectangle of length I x breadth b, wherein I and b are different.

In some embodiments, the device comprises one or more light guide apparatus comprising a geometrically shaped circumferential or partially circumferential light funnel exit and a geometrically shaped circumferential or partially circumferential light funnel entrance to the elongate linear non reflective light path. In some embodiments, the device comprises one or more light guide apparatus comprising a geometrically curved shaped circumferential or partially circumferential light funnel exit and a geometrically curved shaped circumferential or partially circumferential light funnel entrance to the elongate linear non reflective light path.

Preferably, the elongated linear light path is formed by a rigid tube with a light transparent, non- reflective inner light path, for example, a tube with an inner cylindrical light path, an inner a square light path, an inner rectangular light path.

Preferably, the entrance to the elongated linear light path has a geometric (non-planar) circular or elliptical shape such as IT X (a + b)[1 + (3 x h/(10 + - (4 - 3h)))], where a and b are the major and minor radii from which h is derived, and the 3D light path exits a truncated cone through a smaller circle or ellipse positioned at a specified depth d from the entry point and located adjacent to the cornea to produce an uninterrupted ring shaped light spread beam in the equatorial peripheral region of the sclera. For example, the light path boundaries may be formed from an offset overlay of a pair of concentrically aligned straight edged cones or funnels whereby the overlay offset corresponds to the internal light path width of the light path breadth b.

Suitably, the light path has an internal light path with an entrance breadth b to depth d ratio of 1 :2 or more; 1 :3 or more, 1 :4 or more, 1 :5 or more, 1 :6 or more, 1 :7 or more, 1 :8 or more, 1 :9 or more, 1 :10 or more, 1 :15 or more, 1 :20 or more, or 1 :50 or more.

The device described herein may be used to treat one or more specific regions of an eye to be treated, for example, in the equatorial peripheral part of the sclera region of the eye to be treated and particularly the outer layer of the sclera in the targeted areas, for example to arrest the development of high myopia pathology in the treated eye. As the inventors have found in the case of a myopia that significant biomechanical failure occurs in the outermost layer of the sclera, the methods described herein should preferably target the outermost layers of the sclera insofar as possible. In one embodiment of this aspect, the invention provides a device for treatment of one or more specific regions of an eye to be treated, for example, an outer layer of the sclera in one or more equatorial peripheral part of the sclera regions of the eye to be treated, for example to arrest the development of high myopia pathology in the treated eye.

The invention thus also relates to a light delivery device (or use thereof) for delivering light to one or more selectively targeted localized regions in the equatorial peripheral part of the sclera area of an eye to produce a light induced therapeutic effect at the targeted localized regions only. Suitably, one embodiment of the device comprises a contact lens wearable on the eye having an inner concave surface for contacting with a cornea of the eye. In some embodiments, the device may contact the eye and extend beyond the cornea to mask any exposed parts of the eye that are not designated for treatment. The device comprises an outer convex surface provided with one or more light guide apparatus attached at a first part of the light guide apparatus to the outer convex surface of the device. The light guide apparatus are selected, orientated and configured on the device to provide one or more beams (e.g., ring or partially ring shaped beams) of light reaching one or more targeted areas of the eye which is in the equatorial peripheral part of the sclera area/region only. Each light guide apparatus produces a narrow beam of light while blocking disparate wider rays, while the narrow beam of light is then focused through the pupil and the eye optics (crystalline lens). The light guide apparatus has a second part for receiving light from a light source. The light source may be selected to provide a particular type of light (e.g., wavelength, energy, power, intensity, etc.). Suitably the contact lens of the device is wholly opaque to light except for one or more transparent regions where the second part (e.g. funnel entrance) is attached to allow light from the light source entering the second part (e.g., funnel part) of the light guide apparatus to pass right through the light guide apparatus to reach the contact lens and to proceed through the contact lens whereby the light is directed onto the one or more selectively targeted regions of the eye (e.g., as the ring shaped bean or the partially ring shaped beam).

Suitably the device and particularly the light guide apparatus are configured so that on correct fitting of the device onto the cornea of the eye, external light entering the eye is restricted to light travelling through the light paths of the one or more light guides. The opaque nature of the device avoids illumination of regions of the eye other than the particular localized area(s) of treatment in the equatorial peripheral part of the sclera region.

Desirably, the device and particularly the light guide apparatus are configured to deliver light to the selectively targeted one or more regions of the eye the equatorial peripheral part of the sclera region to be treated. In a preferred embodiment, the invention provides a light delivery device to be worn on the eye, in a method of treating a myopia, preventing a myopia or halting myopia progression by light induced biomechanical strengthening of sclera tissue in one or more localised/discrete regions an equatorial peripheral part of sclera of an eye to be treated, preferably which is the circumferential region ranging from up to 60° posterior to the equatorial plane of the eye to up to 30° anterior to the equatorial plane of the eye, the device comprising: an opaque contact lens wearable on the eye, provided with one or more elongated light guide apparatus each mounted at an off-centre location on a convex curved surface of the contact lens at a light transparent region of the contact lens, and, wherein the elongated light guide apparatus comprises a non-reflective internal light path having width to height ratio of 1 :2 or greater, wherein an exit of internal light path contacts the convex surface of light transparent region of the lens at an angle of 5 to 85° to an optical axis of the contact lens, such that collimated light exiting the elongated light guide apparatus passes through the convex surface of the light transparent region and is refracted by optical surfaces of the eye in a direction that illuminates a desired part of the equatorial peripheral part of the sclera of the eye with a light beam with a confined light spread.

Preferably, the light guide apparatus, particularly the inner and/or outer surfaces of the light guide apparatus, are of a material, or are coated with a material, which is designed to, for example, absorb stray NIR. For example, the material, particularly the NIR absorbing material, may be selected from a metal, a glass, a light transparent polymer, 3D printable polymers, or a polymer such as Teflon. Use of 3D printable polymers or computer-controlled cutting from a polymer based block is particularly desirable as these methods means the device will be of a single piece which can be custom printed to any desired eye curvature. It will be understood that the substrate polymers will be opaque to IR, NIR and visible light, etc.

In some embodiments, one or more of the target areas (and thus light spread of illuminated area) may be of a diameter selected in the range of 0.25 mm to 10 mm, preferably about 1 mm to about 5 mm, more preferably about 1 mm to about 3 mm. In some embodiments, the light provided may be in the form of a circular beam which provides a light spot on the target region. In some embodiments, a circular spot of illumination and thus a circular beam is preferred as this is likely to provide sufficient power in the target area to result in crosslinking of the proteins in the tissue in the target areas where crosslinking agent has been provided to the eye to be treated. In some embodiments, several spots may be aligned at the target area to form a ring or slit shaped area of illumination. In some embodiments, the illumination takes the form of an uninterrupted ring or band of light around the entire circumference of the equatorial region of the sclera. In other embodiments, the ring or band of light around the entire circumference of the equatorial region of the sclera can be interrupted if desired, for example, by providing a semicircular region of illumination, illumination in third, quadrants or the like.

It will be understood that light reaching the one or more targeted regions of the eye to be treated in the equatorial peripheral part of the sclera region or where induction of a therapeutic effect is required will be of suitable character to produce the desired effect. As explained above, the light may be used on its own or may be used in conjunction with a light activatable reagent or a drug provided to the eye and in particular the target area for treatment. Preferably, other than a provided pathway though the device, the rest of the device is completely opaque to light such that when the device is being worn/used, the only light entering the eye is light passing through the light guide apparatus of the device. This avoids undesirable or inadvertent production of a therapeutic effect at an area of the eye that is remote or outside the precise area that is to be treated by illumination. It will be understood that the device of the invention is configured, and in particular the contact lens is configured/oriented/dimensioned, so that on correct fitting of the device onto the cornea of the eye, external light entering the eye is restricted to light travelling through the one or more light guide apparatus, that is, the light paths provided by the light guide apparatus.

The light may be of any desired wavelength or wavelengths, energies, phase, intensities, powers or frequencies for a given treatment, depending on the crosslinker reagent/drug used to pretreat the eye/region of interest. However, preferably, the light guide apparatus is configured to discard aberrant rays and cause the light spread to be minimal as the light propagates to the selectively targeted regions of the eye. It will be understood that delivery of light means to illuminate the regions/areas of interest in the equatorial peripheral part of the sclera with light provided through the device that passes through the pupil. The light used can be NIR, red, UV or blue light or combinations thereof. NIR light is preferred for crosslinking, particularly in the sclera regions, as NIR light would readily reach the desired scleral region. The device may be used with any one or more light sources that simply need to be able to project sufficient primary rays through the pipe and parallel to the walls of the pipe. In some embodiments, LED sourced light is preferred.

Suitably, the light guide apparatus comprises an internal light path which is substantially straight between the first and second parts (light entrance, e.g., light funnel entrance, and light exit, e.g., light funnel exit) of the light guide apparatus. In embodiments, the internal light path may hollow or may be filled with a light transparent material. The internal light path provides a transparent pathway for light sourced externally from outside the eye to enter the eye through the pupil via the device. Desirably, no other light passes through the device into the eye other than through the light path.

Suitably, the light guide apparatus has an internal light path with an entrance width to light path depth d ratio (w/d) of 1 :2 or more; 1 :3 or more, 1 :4 or more 1 :5 or more, 1 :6 or more, 1 :7 or more, 1 :8 or more, 1 :9 or more, 1 :10 or more, 1 :15 or more, 1 :20 or more, or 1 :50 or more. An internal light path with a such a ratio of from 1 :5 to 1 :10 is particularly preferred, for example, 1 :5, 1 :6, 1 :7, 1 :8, 1 :9, 1 :10 or 1 :20, etc.

The angle at which the exit of the internal light path of a light guide apparatus contacts the convex surface of light transparent region of the lens may range from 5° to 85°, 10° to 85°, 15° to 85°, 20° to 85°, 25° to 85°, 30° to 85°, 35° to 85°, 40° to 85°, 45° to 85°, 50° to 85°, 55° to 85°, 60° to 85°, 65° to 85°, 70° to 85°, 75° to 85°, 80° to 85°, and all angles therebetween, to an optical axis of the contact lens. In some embodiments, the angle is not greater than 85°, e.g., not 86°, 87°, 88°, 89° or 90° to the optical axis of the contact lens. In some embodiments, an angle of from 20° to 85° is preferred. In other embodiments, an angle of from 35° to 85° is preferred.

Conveniently, adjustment of the entrance (e.g. light funnel entrance) width to light path depth ratio (w/d) of the light path alters the diameter/light spread of the light emerging from the outside of the light guide apparatus which enters the eye. It will be understood that longer light paths (depth of light path from entrance to exit) form narrower spreads/less diffused/more sharply focused beams reaching the target area, while the narrower the width of the entrance light path, the narrower the width of the beam in one dimension. Likewise, the length of the entrance to the light path (and/or the length dimension travelling along the path) determines the length of the bean in the other dimension. Thus adjustment of the light path depth and the dimensions of the light path entrance (and constant width of the light path along on the depth of the light path) adjusts the focus of the beam and thus the dimensions of the width and length of the illuminated region in the targeted tissue. Thus, by adjusting the dimensions of the light path, control of the focus of the beam and the size/shape of the illuminated area can be designed as required.

Preferably, light path width w of from about 0.25 mm to about 2 mm or 3 mm (or in some embodiments up to 3 mm, e.g., for the light funnel), most preferably from about 0.5 m to about 1 mm.

In preferred devices of the invention the first part of the light guide apparatus is located a predetermined position on the outer convex surface of the lens such that the exit interfaces at a light transparent region of the lens which is located adjacent the pupil of the eye to be treated when the lens is worn. For example, the orientation of the light guide apparatus on the contact lens may be nasal for temporal stimulation, temporal for nasal stimulation, superior for inferior stimulation or inferior for superior stimulation. Furthermore, the distance of the light guide apparatus from the lens center will vary with the contact angle. In preferred embodiment, the design will use the flattest/shallowest oblique angle that can allow light to pass through the pupil to exclusively illuminate the targeted equatorial region. It will be understood that contact angle controls the direction of light projected from the device into the eye through the eye optics. The light emerging from the device is preferably well focused into a narrow substantially collimated light beam (e.g. having a narrow light roaming distance) so that the light can form a well focused, minimally diffused narrow light spot on the one or more localized target areas. In other embodiments, the device including the light guide apparatus may be 3D printed, such that the device is a single piece. In this case, the ending of the tube part where it contacts the contact lens will be matched to the curvature of the contact lens, which in turn is matched to the persons corneal curvature.

In some embodiments, the material of the device is opaque inherently, and if necessary, the component of the device including the light guide apparatus can be made opaque or more opaque by providing the material and/or components with a coating of opaque material such as a pigment or a film that is non-transparent to light on the external and/or internal surfaces of the device. Such an opaque coating o that is non-transparent to light can also be provided on the inner and/or external parts of the light guide apparatus if necessary. Where a light opaque 3D printable polymer is used, it will be understood that there will be no requirements for a non-transparent light coating.

As explained herein, when the light guide apparatus is in the form of pipe, the light reaching the target area has a narrow light roaming distance, preferably in the range of from about 0.5 mm to about 20 mm, more preferably 7.5 mm to 15 mm, most preferably about 10 mm. In this case, “about” means ± 5 %.

Desirably, the contact lens may be formed or cut from a rigid material such as PMMA or a soft and/or flexible material, such as silicone, or more preferably 3D printable polymers. In some embodiments, any material having good oxygen permeability is ideally used. Such materials are known in the art of contact lens manufacture but are treated or modified to render them opaque. However, the light guide apparatus or pipes need to be rigid/stiff so that they do not bend. Suitably, inside surfaces of the light guide apparatus or pipes need to be smooth.

As used herein, the term “contact lens” is not intended to be limited to a contract lens in the traditional sense that has visual corrective power and is light transparent. The term is intended to cover any curved shell-like structure which approximately matches the curvature of the cornea so that it can be worn on the eye and serve as a base or foundation for the light guide apparatus as described herein. In preferred embodiments, the contact lens is in the form of a truncated curved shell. Desirably, the contact lens is in the form of an opaque contact lens, particularly opaque piano contact lens, independent of vision correction. Desirably, the contact lens is in the form of an opaque curved shell, particularly an opaque truncated curved shell, independent of vision correction.

Suitably, the position and/or angle of the light guide apparatus selectively targets delivered light to one or more discrete areas or regions of the peripheral sclera of the eye, particularly at a zone spanning an equatorial axis of the eye or a zone between an equator and limbus of the eye. However, for myopia treatment, the targeted area could be extended to include anywhere else the sclera has a thin appearance, or in the case no thinning is yet apparent, in the equatorial zone.

Preferably, the device is configured such that the light targets the outermost layer of the sclera. That is, the light spot/area of illumination exclusively falls on the outermost layer of the sclera in the targeted regions of interest. Suitably the device is configured such that the light does not illuminate the blind spot of the eye to be treated.

In some embodiments, for example, in a preferred device the position and/or angle of the light guide apparatus and light path resulting therefrom selectively targets delivered light to a particular horizontal azimuth just below an equator of the eye globe.

Desirably, wherein the light guide apparatus is attached to a central region of the contact lens around the area that lie adjacent to the pupil when worn, preferably which is in the form of truncated spherical shell.

In some embodiments, particularly where targeting more than one, or multiple regions of the equatorial peripheral part of the sclera region of the eye, a preferred device comprises a plurality of light guide apparatus attached to the outer convex surface at respective angles and/or positions to illuminate different selectively targeted regions of the eye in the equatorial peripheral part of the sclera region.

Preferably, when present, the plurality of light guide apparatus are disposed in a circumferential array and attached to the contact lens at respective positions adjacent a central region of the central portion.

In preferred devices, each light guide apparatus includes a light path in the form of a substantially tubular, circular bored, light pipe that extends longitudinally between the first and second parts (entrance and exit) of the light guide apparatus/path. As explained above, the depth of the path through which light travels through the light path can be adjusted to provide a desired roaming distance/degree of focus for a beam and thus the illuminated region on the one or more areas of targeted tissue.

It will be understood, that where necessary, the use described herein is in conjunction with a crosslinking drug or reagent pre-delivered to the eye, preferably non-selectively pre delivered to the eye which includes the equatorial peripheral region, preferably during a treatment of a myopia, particularly high myopia.

In a preferred use of the device of the invention, delivery of light to the selectively targeted region treats and/or prevents a myopia such as high myopia, school myopia, high myopia, pathological myopia, progressive myopia or any other form of myopia, preferably high myopia.

In preferred embodiments, the device is used in conjunction with a light source. Suitably, the light source allows control of light parameters including wavelength, power, brightness, intensity, etc. The light sources which may be used with the device of the invention will be known in the art. A particular advantage of the present invention therefore is that the light delivery device that does not need to depend on a laser collimated light source, which is more likely to cause thermal damage to ocular tissues compared to LED light stimulation.

In one embodiment, the light source comprises one or more LEDs including a low power single LED; a high power single LED; a low power multiple LED array; or a high power multiple LED array. In some embodiments, the light sources comprise one or more LED, preferably NIR LEDs. The light may be of a suitable wavelength to active cross-linking agent at the localised target region of interest.

The light is directed from the light source through a device of described herein when positioned on the eye to be treated to exclusively illuminate the selectively targeted localized or discrete regions in the equatorial peripheral part of the sclera region. Suitably, the light is provided to the region of interest in the form of a narrow diameter/narrow spread light spot/area/region as described above. That is the tissue contacted by light spot/area/region is confined to specific localized targeted region which means the location of crosslinking can be more precisely controlled, improving the safety of the method.

Description of Preferred Embodiments

The present invention is described with reference to the following examples. It is to be understood that the examples are illustrative of and not limiting to the invention described herein.

Myopia alters the microstructural and biomechanical properties of the posterior sclera. The inventors have used scanning acoustic microscopy (SAM) which measures biomechanical properties that are related to tissue microstructure, and second-harmonic generation (SHG) microscopy imaging to investigate the finding of biomechanically-distinct scleral layers and to identify relationships between mechanical properties and tissue microstructure in myopic guinea pig (GP) eyes. As a result, the inventors have discovered the posterior sclera exists as a layered structure with potentially different collagen fibril characteristics. Indeed, the inventors have found that the posterior sclera exhibits biomechanically distinct layers that are affected differently in myopia. Surprisingly, it was found that some changes were greatest in more-peripheral regions, which have led to the understanding that interventions to strengthen the sclera may be effective away from the optic nerve and efficacy may be achieved best when such intervention is applied to the outermost layer or layers of the sclera.

The current study investigates the layered sclera structure using a large number of tissue sections using matched control and myopic eyes. SHG imaging was employed in addition to SAM to determine the scleral microstructure of the biomechanically-distinct scleral layers. Comparison of these complementary imaging modalities on adjacent tissue sections was used to investigate relationships between the microstructural tissue properties and bulk mechanical properties of myopic and control eyes.

EXAMPLE 1 - Evidence for biomechanical changes in the equatorial peripheral region of the sclera in eyes developing myopia

Animals in this study were maternally-reared guinea pigs (N=6) raised in white-light LED illumination. From 4 days of age, the right eyes were form deprived by placing a translucent diffuser over the eye until 12 days of age. Contralateral left eyes were left as untreated controls. Cycloplegic refractive error and ocular length were measured on day 12 after 8 days of diffuser wear following our published methods (1 -2 drops of 1% cyclopentolate, with measurements 1 ,5-2h later using a Nidek autorefractor and A-scan ultrasonography with 20MHz center frequency, replacing diffusers after each measurement). The term “induced myopia” is defined as the level of induced form-deprivation myopia (FDM).

Animals were sacrificed at 12 days of age by first deeply anaesthetizing them with isoflurane in oxygen, followed by a cardiac injection of 0.5ml pentobarbitone. Both eyes of each animal were rapidly enucleated and frozen in a beaker of isopentane surrounded by liquid nitrogen. Eyes were stored at -80 C prior to embedding them in medium (Tissue-Tek optimum cutting temperature, O.C.T.). Whole, unfixed globes (FD73 treated and contralateral control) eyes were vertically cryosectioned in the sagittal plane every 12 pm across the entire posterior pole. Sections from the central axis, nasal edge of the optic-nerve head (ONH), or the vertical midline of the ONH were mounted on glass slides. Prior to SAM imaging, slides were placed in a saline bath for 10 minutes to ensure complete thawing and rehydration. The adjacent slides were subsequently processed for SHG imaging.

Scanning Acoustic Microscopy

SAM imaging was performed using a custom-designed system at Riverside Research. Briefly, a 250- MHz ultrasonic transducer (F-number 1.16, 160-MHz bandwidth, Fraunhofer, IBMT, Sulzbach, Germany) was attached to a 3-axis linear positioning system (Newport, Irvine, CA, USA). The transducer had a 7 pm resolution and 72 gm depth of field. Sample slides were mounted in an “upside-down" configuration and a drop of degassed saline acoustically coupled the transducer to the sample. A 300-MHz monocycle pulser (GEOZONDAS, Vilnius, Lithuania) excited the transducer as the sample was raster scanned in two dimensions with a 2 gm step size. Radio-frequency (RF) echo signals were amplified (MITEQ, Hauppauge, NY, USA) and digitized at 2.5 GHz using a 12-bit HD oscilloscope (HD06104, Teledyne Lecroy, Chestnut Ridge, NY, USA). The temperature of the coupling fluid was measured pre- and post-scanning using thermocouples. Custom LabVIEW (National Instruments, Austin, TX, USA) software controlled the SAM system.

Second Harmonic Generation Imaging

SHG images were acquired at the Confocal and Specialized Microscopy Shared Resource (CSMSR) at Columbia University. Slides with thawed samples adjacent to those scanned with the SAM system were mounted in a confocal microscopy instrument consisting of a Nikon A1 R-MP laser scanning system on an Eclipse Ti inverted stand (Nikon Instruments, Melville, NY, USA). The attached Nikon 25x/NA 1 .1 Apo LWD water-immersion objective was coupled to the sample with a drop of water. A laser tuned to a 860nm wavelength (5.2W power and 140fs pulse width) excited the tissue sample and backscattered SHG signals in the 400-450nm wavelength range were recorded. Resulting images had isotropic resolution with 0.512 gm pixel size and covered a region approximately 2.5-3.5mm x 2.5-3.5mm. After SHG imaging, sections were stained with Haemotoxylin and Eosin (H&E) to provide a morphological reference for SHG and SAM images. Image Segmentation

Acoustic parameter maps and SHG images were manually segmented to delineate the scleral edges and create exclusion masks to ignore sectioning artifacts or extraneous tissue in post-processing. SHG images were also manually co-registered with H&E stained histology images to identify the section of the sclera captured in the field of view, which allowed SHG images to be defined in terms of the distance from the ONH as shown in Figure 1a. The ONH was visible in the acoustic-parameter maps, enabling coregistration of SAM data with histology.

SHG images and parameter maps were further subdivided in two ways. First, starting at the center of the ONH (or edge of the OHN if center not available in the image, Figure 1a), regions of interest (ROIs) were defined that spanned 200 pm along the length of the sclera. An example of ROIs defined for a segment of the sclera is shown in Figure 1b.

Second, the sclera was divided into four layers of equal width (Figure 1c-d), with layers 1 and 4 being the outermost and innermost layers, respectively.

Signal and Imaging Processing

Two-dimensional (2D) maps of acoustic properties were estimated from the SAM RF echo-signal data using a frequency-domain, model-based approach. Quantitative estimates of bulk modulus (K), mass density (p), and acoustic attenuation (a) were made at each scan location. For linear-elastic materials, K is related to the shear modulus (through Poisson’s ratio) and measures the resistance of a material to volumetric loads; a larger value of K indicates a stiffer material, a measures the energy loss as an acoustic wave propagates through a medium, with larger a corresponding to higher energy loss. Typically, a is described with units of dB/MHz/cm. All values of a were converted to dB by assuming a 250-MHz frequency and 100pm unit thickness. As such, a is interpreted as the 250-MHz acoustic energy lost (in dB) for every 100pm of tissue in the path of wave propagation. Collagen fiber characteristics were quantified from SHG images using the open source software CurveAlign. CurveAlign applies a curvelet transform to filter SHG images and highlight collagen fibers before executing the fiber extraction (FIRE) algorithm to automatically detect and trace collagen fibers. For each fiber identified, CurveAlign computes the length, diameter, angle relative to nearest sclera boundary, and straightness. Fiber straightness is defined as the length of the straight line connecting the ends of the fiber divided by the total fiber length. In this study, estimates of fiber orientation were used to compute the local alignment of fibers that corresponded to the population mean resultant length from the circular statistics. Values of alignment range from 0-1 , where 0 indicates random orientation and 1 means fibers were parallel. Collagen fibers identified in CurveAlign usually spanned more than one ROI. The center points of fibers were used to determine ROI assignments. After assigning collagen fibers into a ROI, we computed the collagen fiber number density for each ROI, defined as the number of collagen fibers per mm2 (#/mm ² ).

Statistical Analysis

Depending on the statistical comparison, mean and SEM of acoustic parameters or collagen fiber features were computed by whole eye, ROI, or by layer within an ROI. An independent-samples t-test was used to compare parameter means between control and myopic eyes. One-way ANOVA was used to compare inter-layer differences within control and myopic eyes for each parameter, followed by a Tukey post-hoc test to identify layers exhibiting distinct acoustic or collagen fiber structure properties. Significance was defined as p-values less than 0.05. Relationships between parameters and eccentricity (reported as distance from ONH) were evaluated with linear regression analysis. Statistical values reported are slope of the regression line, p-values, and Fl ² . Linear regression was also used to identify relationships between acoustic-parameter values and collagen fiber characteristics. All statistical analyses were performed using Python 3.7.

Results

The four pre-defined layers of the sclera had distinct mechanical properties. Short-term FDM caused significant changes in acoustic properties in the outermost and innermost layers of the sclera. Acoustic parameters were correlated with collagen fiber structure as quantified from SHG images, suggesting that information pertaining to tissue microstructure can be obtained from quantitative SAM measurements. Properties of Whole Eyes

Induced relative myopia ranged from -3.21 D to -9.29D. Ocular lengths for all eyes ranged between 7.85mm and 8.14mm and were found to be larger in myopic eyes when evaluated with a paired t-test (p = 0.006). Acoustic attenuation awas the only parameter found to be correlated with refractive error (R ² = 0.307, p =0.03), although it was not correlated with ocular length (R ² = 0.307, p = 0.012). Comparing mean acoustic properties between control and myopic whole eyes (averaged across all layers and all ROIs, Table 1), K and a were significantly smaller in myopic eyes (p < 0.05) whereas no difference was observed in p (p = 0.25). Collagen fibers were 0.6% straighter (p = 0.004), 3.5% more aligned (p = 2.2 X 10 ^-12 ) and exhibited an average fiber width 0.162 pm smaller (p= 1 .1 X 10 ¹¹ ) in myopic eyes compared to control eyes. No significant differences were observed in the mean fiber length (p = 0.06) or number density (p = 0.77) between whole control and myopic eyes. Pair-wise comparison of fiber parameters among all eyes revealed significant correlations, with longer fibers tending to be more aligned (R ² = 0.674, p = 0.0002, thinner (R ² = 0.311 , p = 0.03), and expressed with lower number density (R ² = 0.357, p = 0.01 ). An interesting result was that fiber number density was positively correlated with straightness R ² = 0.762, p = 2.2 X 10 ^-5 ) and negatively correlated with alignment (R ² - 0.888, p = 1 .5 X 10 ^-7 ).

Differences between Scleral Layers

A qualitative review of the acoustic parameter maps suggests a layered structure of the sclera as shown in the example K map in Figure 2a. Across all eyes, layers 1 , 2, and 3 exhibited some statistically similar mean acoustic properties, but all three were significantly different from the acoustic properties in the innermost layer 4 (Table 1 , see Figure 16). Bulk modulus was 0.13-0.25GPa higher in layers 1 -3 when compared to layer 4 (p = 0.001 for all) in control eyes and similarly 0.14-0.28 GPa higher (p = 0.001 for all) in myopic eyes. Likewise, when comparing layers 1 -3 to layer 4, acoustic attenuation (a) was found to be 2.09- 3.96 dB higher in control eyes (p < 0.01 for all) and 4.96-6.81 dB higher in myopic eyes (p = 0.001 for all). No significant differences in mass density occurred between any 2 layers in myopic eyes, although the mean value was 0.01 -0.02g/mm ³ higher in layer 4 of control eyes (p < 0.03 for all)

Within layers 1 and 4, mean values of bulk modulus (K) were found to be lower in myopic eyes compared to control eyes as shown in Figure 3a (0.08 GPa and 0.09 GPa difference, p = 0.034, 0.001 respectively). Similar results were found for a as shown in Figure 3c where values were higher in layers 1 (1 .51 dB, p = 0.034) and 4 (3.74 dB, p = 2.5 x 10 ⁷ ) of control eyes compared to myopic eyes. In contrast, p was found to be higher in myopic eyes as shown in Figure 3b and only within layer 4 (0.01 g/mm3, p = 0.001 ).

An example of identified collagen fibers is shown in Figure 2b. Collagen fibers were significantly thinner and more aligned within every layer of the sclera in myopic eyes compared to control eyes (See Table 1 and Figure 4a, b). However, fiber length and number density varied between different layers within control eyes. Specifically, in control eyes, fibers become longer (12.7 pm longer, p = 0.008) and expressed in fewer numbers (161 fewer fibers/mm2, p = 0.006) the closer the layer was to the innermost scleral surface (layer 4). However, no significant variation was found between the different layers in myopic eyes (Figure 4). Nor were any differences in fiber alignment or straightness found among layers in either control or myopic eyes (Figure 4b, c). Relative to control eyes, the collagen fibers were longer by 9 pm (p = .01 , Figure 4a) in the outermost layer 1 of myopic eyes and were less dense by 320 fibers/mm ² in layer 2 of myopic eyes as shown in Figure 4e.

Changes with eccentricity from the Optic Nerve Head

Among control eyes, an increase with distance from the ONH (maximum eccentricity was 3.5 mm) existed for K (Figure 5a) and p (Figure 5b), whereas a did not significantly vary over these same distances (Figure 5c). More specifically, K increased by 0.09GPa for every 1 mm increase in distance from the ONH and p increased by 0.01 g/mm ³ with every 1 mm increase in distance. In contrast, K in myopic eyes decreased by 0.04GPa/mm (p = 0.006) and no significant trend was observed with eccentricity for p or a (respectively). The R ² and p-values computed by the linear regression are included within the corresponding figures.

Fiber length also increased with distance from the ONH within control eyes at a rate of 8.95pm/mm (Figure 6a). Furthermore, in control eyes, fiber alignment increased with eccentricity (Figure 6b) while fiber number density declined by 311 fibers/mm ² (Figure 6c). No significant variation with eccentricity were observed in collagen fiber width (Figure 6d) or straightness (Figure 6e) in control eyes. Collagen fiber length and alignment increased with eccentricity at rates in myopic eyes slightly less than in control eyes (6.45gm/mm and 0.26au/mm, respectively). Fiber number density also decreased by -292 #/mm ² with eccentricity. Unlike control eyes, fiber width in myopic eyes decreased at a rate of -0.1 1 |im/mm. When considering layers independently, K in control eyes increased with eccentricity in the outer layers 1 and 2 only (Figure 7a). No layers in myopic eyes exhibited a significant change in value with distance from the ONH (Figure 7c). Similarly, there was no change in fiber width within any layer of control eyes (Figure 7b) whereas fiber width decreased within all layers of myopic eyes (Figure 7d).

Correlations between SAM and SHG Parameters

Acoustic and fiber parameters were binned by ROI over all eyes and layers and compared using linear regression to investigate correlations. A total of 15 comparisons were made. Full results are compiled in Table 2 (see Figure 17). Among the pairs of correlated complementary parameters, acoustic attenuation was strongly correlated with collagen fiber length (R ² = 0.664, p = 2.1 x 10 ⁴ ), alignment R ² = 0.713, p = 7.6 x 10' ⁵ ), and number density (R ² = 0.758, p = 2.4 x 10 ^-5 , Table 2).

Acoustic attenuation was also weakly correlated with fiber straightness (R ² - 0.389, p - 0.01 ). K was positively correlated with fiber alignment (R ² = 0.343, p = 0.02) and negatively correlated with fiber width R ² = 0.351 , p = 0.02). A statistically insignificant correlation was found between K and fiber length (R ² - 0.25, p = 0.052). Mass density had no significant correlation with any collagen fiber features except for fiber straightness specifically in layer 4 (Figure 8c).

Acoustic and fiber parameter values were grouped for layers 1 -3 (because of the similarity in acoustic properties stated above) and the correlation between complementary parameters was computed (30 total comparisons, Table 2). Figure 8a-c show example correlations after grouping the parameters by layers 1 -3 or layer 4. When evaluating relationships within grouped layers 1 -3, a was correlated with fiber length, alignment, and number density (Figure 8a) while K was significantly correlated with all collagen fiber parameter values (example in Figure 8b).

Interestingly, layer 4 exhibited strong correlations between p and fiber length, alignment (Figure 8c), and fiber number density, while no correlation between p and any fiber parameter was found in the grouped layers 1 -3. Likewise, K and a in layer 4 were uncorrelated with any of the collagen fiber features measured. Discussion

The results support a layered structure of the posterior sclera and reveal the relationships between mechanical properties and collagen microstructure. By scanning adjacent unfixed tissue sections with either SHG or SAM, complementary information of tissue properties at the microscale were obtained. Furthermore, data obtained from control and form-deprived eyes provides insight into how the sclera changes in shortterm myopia. Comparisons of K and p between control and myopic sclera were in accordance with previous findings. In particular, the finding that K was reduced in myopic eyes is consistent with previous reports that higher levels of myopia correlate with a mechanically weaker sclera. It is known that myopic sclera thins, and thinner tissues may be thought to be the cause of biomechanical weakening. However, the present measures of K here are completely independent of the thickness of the sclera, suggesting that intrinsic changes occur within the microstructure of the sclera that induce biomechanical deficiency. Furthermore, these microstructural changes occurred relatively early in myopia development in contrast to the collagen remodeling that has been noted to take some time to develop.

Acoustic attenuation a was included as an additional parameter in the present investigation due to preliminary results indicating significant differences between control and myopic eyes and their relationship to collagen fiber features. Linear regression analyses between a and K or p showed no correlation, as expected. This suggests that a is an acoustic parameter that is not necessarily tied to mechanical properties. Interestingly, a was the only parameter found to be correlated with refractive error during the early development of myopia. Specifically, the acoustic attenuation was reduced in myopic eyes meaning acoustic signals transmitted more readily through myopic sclera.

Layers in the sclera

The sclera was split into four equal-width layers for processing based on findings from another study where the authors noticed an apparent layering in the K and p maps of posterior sclera sections of GP eyes. Results from this larger sample size support the hypothesis that different layers in the sclera exhibit different mechanical and microstructural properties. By investigating the layered structure of the sclera in a form deprived myopic guinea pig model, the present results can begin to provide insight into more granular alterations in the mechanical and microstructural changes associate with myopia. Within control or myopic eyes, K and a tended to be larger in the middle layers, although the most significant differences occurred in layer 4. Layer 4 aligns with the innermost layer of the sclera (the lamina fusca), which is separated from the underlying choroid by a thin potential space known as suprachoroidal space. The lamina fusca has an abundance of melanocytes which may result in a higher cell density than the overlying sclera stroma. Considering this, it is interesting that myopic eyes failed to show the normal greater relative mass density in the lamina fusca compared to the overlying sclera layers. Collagen fibers were also longer and less dense in this innermost layer of control eyes compared to the outermost. Others have found that the outer scleral region comprises layers of slender collagen bundles and hypothesized that the intertwining of these collagen bundles was important for giving the eyeball its rigidity and flexibility, a hypothesis later supported through simulated comparisons of mechanical models with and without fiber interweaving. In comparison, results of the present study indicate a larger number density of wider collagen fibers in the outer layers of control eyes but significantly greater fiber alignment in myopic eyes. One interpretation of these results is that control eyes exhibit a greater number of thicker, interwoven collagen fibers, consistent with the findings of Komai and Ushiki. Given that chemical collagen crosslinking treatments aim to increase the rigidity and reduce the compliance of the sclera, results from this study may imply that crosslinking procedures would be most effective when targeting the outer sclera. This is further supported by the finding that the biomechanical properties tend to be significantly affected by myopia in this outermost layer (cf. Figure 7a, c).

The observed reduction in fiber width at greater eccentricities in myopic eyes (Figure 6d), also suggests that collagen crosslinking-type treatments may be more important at distances further from the ONH, or at least up to distances of 3.5 mm measured in the current study. The guinea pig optic nerve is located ~10 degrees temporal to the posterior pole. Thus 3.5mm, where the largest changes in fiber thinning occurred, corresponds to ~30 degrees nasal and ~60 degrees temporal displacements from the posterior pole (Figure 12E). Applying these results to the human eye where the macula is located 17 deg temporal to the optic disc, suggests that crosslinking treatments that avoid the disc as well as the fovea/macula may be effective (cf. Figure 12D and F). Given the large differences between acoustic parameters in control and myopic eyes as a function of eccentricity, collagen fiber features interestingly demonstrate more subtle contrasts. Only trends in fiber width between control and myopic eyes deviate, with fibers maintaining a constant width along the sclera arc in control eyes and significantly decreasing farther from the ONH in myopic eyes. No significant variation in the trends among layers were observed. Collagen fibers possibly would exhibit more significant differences either in whole eyes or among layers in more advanced high myopia.

Relationships between acoustic properties and collagen organization

Collagen fibers were consistently thinner and more aligned in myopic eyes compared to control eyes. Bulk modulus was significantly correlated to fiber alignment and width, consistent with previous studies employing wide-angle X-ray scattering showing evidence of reduced collagen fiber alignment in mechanically weaker sclera. However, this result is apparently at odds with the fact that fibers were more aligned in myopic eyes in the current study. The correlation between bulk modulus and fiber width was unexpectedly negatively correlated considering previous reports of decreased collagen fibril width in mechanically weaker myopic eyes. The apparent contradictions may be due to differences between early and later sclera remodeling, given the short-term FDM induced in GP eyes imaged in this study, and the fact that SHG is sensitive to collagen fibers (aggregates of fibrils) whereas the previous histological studies evaluated characteristics of the fibrils. Note that the sclera is a viscoelastic material, and the time-dependent response is not captured by SAM imaging or histological analyses.

The acoustic attenuation of the sound wave (a), which was reduced in myopic eyes, correlated with several fiber features: a increased as fibers became straighter and more aligned but decreased as the fibers increased in length and number density. Although fibers were more aligned in myopic eyes, they were also consistently thinner. This latter finding is consistent with the previously observed increase in smaller diameter collagen fibers in myopic tree shrew eyes associated with an increase in the number of small fibers in myopic compared to control eyes. It would be expected that increased numbers of smaller diameter fibers would increases scattering and cause greater acoustic attenuation, reducing the capacity for acoustic signals to readily transmit through the sclera.

In summary, results of Example 1 show that the ex vivo posterior sclera exhibits a layered structure with distinct mechanical properties. Short-term myopia induced by form deprivation leads to significant changes in the acoustic properties in the outermost layers of the sclera as well as changes in width and alignment of collagen microstructure. Measured acoustic properties are correlated with the collagen fiber features, implying that quantitative SAM measurements can be used to glean information about mechanical properties and tissue microstructure concurrently.

EXAMPLE 2 -treatment regions for myopia

The inventors believe that there is (a) a well-defined progression in the changes in eye shape that precede myopic pathology, and (b) that fiber thinning is initiated in the anterior sclera before the changes are detected at the posterior pole.

The inventors have based their results on the study of the sequence of events in an animal model of myopia. Specifically, it has long been known across many species that myopia rapidly develops when eyes are form-deprived (but not light deprived) such as occurs in ptosis (dropped eyelids) in humans or by wearing diffusers in animals. The inventions have found that in a mammalian model of myopia using guinea pigs, high myopia (up to -15D) can be produced when the eye is deprived of high spatial frequencies under specific lighting conditions for an extended period. In these eyes, the area around the optic nerve balloons outward (Figure 11), and in some eyes, staphyloma eventually form around the margins of the optic disk.

However, prior to these events, the eye shape is initially affected in the periphery of the eye (Figure 11). The influence of peripheral signals in mediating the development of myopia is not new. A myopic eyeball is egg shaped, and it is well known that the central axis is myopic (eyeball too long) while the periphery is less myopic (or relatively hyperopic) when compared to the degree of myopia on the central axis. The understanding of the role of this difference between central and peripheral defocus on refractive development has been influenced by animal studies that show that the growth of the eye is regulated by the sign of defocus. For example, young animals that wear negative or positive lenses compensate for the imposed defocus and become emmetropic with no refractive error while wearing the spectacle lens but are myopic or hyperopic respectively when measured without the spectacle lens in place. This phenomenon is known as spectacle lens compensation (SLC) whereby eyes grow excessively in response to negative/hyperopic defocus (where objects focus behind the image plane) while they inhibit their growth in response to imposed positive/myopic defocus (where objects are short-focused in front of the image plane).

Single vision lenses, that correct the on-axis myopic blur in myopes, also create relative hyperopic defocus in the periphery. Based on SLC, a hyperopic signal in the retinaviiW drive the eye to grow even faster and exacerbate myopic progression. The findings of SLC provide the basis for many new anti-myopia lens designs based on deliberating introducing relative myopic defocus in the periphery to induce an inhibitory growth signal. Less understood, is how these peripheral signals end up causing changes in the sclera structure at the central posterior pole. This is all the more perplexing, since it has been shown that eye growth responds locally to defocus, with growth changes restricted to the hemifield that has experienced defocus.

The inventors now propose a different scenario that during the development of myopia, remodelling of the sclera is actually initiated in the periphery (towards the anterior sclera (front of the eye) rather than at the posterior pole (at the back of the eye). Therefore, the inventors propose that the treatment location for those at risk of developing high myopia pathologies should target the peripheral sclera, and specifically the outer layers and in particularly the outermost two layers of the sclera (see Example 1 above). This approach is both technically feasible, located towards the front of the eyeball so more easily accessible and is distant from the optic nerve so relatively safe.

It is based on the following logic:

(1) The choroid constrains the shape of the eyeball

Van Alphen showed that eyes in which the sclera has been completed removed perfectly maintain their shape showing that the choroid constrains the shape of the eyeball. We have found a similar effect in young guinea pig pup eyes (Figure 9) despite being much softer and more elastic than adult eyes.

(2) The weakest point in the choroid occurs in the anterior eyeball

Van Alphen went on further to demonstrate that when stress is applied through a gradual increase in intraocular pressure, adult eyes expand anterior, not posteriorly. The posterior surface remains in a constant position, but in eyes without a sclera, the anterior eyeball extrudes through the pupil in the front of the eye. He further claims that the weak point occurs near the muscles that control and surround the crystalline lens and iris.

The inventors have found that when a young growing eyeball, this time with its sclera intact, is subjected to increased IOP, it also expands anteriorly. Eventually, with very high levels of IOP, the eye will dramatically burst through the anterior eye. This demonstrates that a significant weak point of the eyeball structure is located in the anterior eye.

Furthermore, the inventors have demonstrated that when the posterior eyeball is cross-linked so that is simply cannot expand posteriorly, under increased IOP, the eyeball expands through the cornea, eventually bursting at the limbus.

(3) Myopia causes changes in elasticity of the outer layers of the sclera in the periphery It is known that the modulus of elasticity for human scleral strips is higher in the anterior sclera compared to the posterior. The extensibility of human and pig scleral strips of different directions is similar at the equator and near the limbus in anterior sclera, but both are much less extensible than the posterior sclera. However, this hyperextensibility of the posterior sclera is normally buffered by a relative increase in its thickness. There is conflicting evidence regarding the changes in scleral thickness in human myopes when comparing anterior to posterior regions, although it has been extensively demonstrated that the sclera is particularly thin at the posterior pole in high myopes.

Using new SAM technology, the inventors have demonstrated in guinea pig eyes that the bulk modulus K, is greater at 3.5 mm from the optic nerve compared to locations closer to the optic nerve independent of differences in wall thickness. 3.5 mm corresponds approximately with the equator of the eyeball. (See Example 1 above). This means the inventors have demonstrated that the sclera is normally stiffer at the equator compared to the posterior globe. Furthermore, the inventors have also shown the unique finding that this is specifically due to the biomechanical properties in the outermost sclera layers (Figure 7, Layers 1 and 2).

In highly myopic eyes, a thinner scleral wall will increase wall stress and this reduction will likely enhance extensibility. Indeed, there is ample evidence that sclera strips from the posterior pole in advanced myopic eyes have an increased creep rate. During myopia development, the inventors have found that the bulk modulus of the outermost layer of the sclera is reduced not at the posterior pole, but in fact is reduced towards the equator of the eye. This demonstrates that the weakest part of the sclera during the early development of myopia occurs at the equator in its outermost layers. This suggests that crosslinking the outermost layer of the sclera in the equatorial peripheral region could protect the eye from myopic progression.

(4) Eyes developing myopia show the largest changes in collagen fiber diameter in the peripheral sclera

Previous studies have generally focussed on changes at the posterior pole of the myopic eye and have not taken into account the precise location. Using second-harmonic generation (SHG) microscopy, we have measured the changes in collagen characteristics in whole eye slices allowing us to directly compare these changes as a function of eccentricity from the optic nerve. We find that the collagen fibers thin in eyes developing myopia in the peripheral sclera throughout its depth rather than at locations closer to the optic nerve head (Figure 7D).

(5) During the development of myopia, the initial changes occur in the periphery of the eye, which subsequently progress towards staphyloma at the posterior pole of the eye

The inventors have tracked the shape changes in the eyeball during the development of myopia in the guinea pig and find that initial shrinkage occurs in the periphery, that this precedes the development of staphyloma-like changes centered around the optic nerve head. (Figure 11) This work reinforces the idea that treatment of the periphery early in the development of myopia could have beneficial effects in inhibiting subsequent myopic progression.

EXAMPLE 3 - Device for implementing methods of the invention

The invention extends to a device for implementing the methods of the invention device. The device has arisen from a need to enable selective light treatment of a target localized area of the eye, for example, using crosslinking exclusively at or near the equatorial peripheral part of the scleral region to treat/prevent a myopia or progressing of myopia in a non-invasive or at least minimally invasive manner compared to existing approaches. It will be appreciated that where drugs are applied, their application typically involves an invasive step as the drug needs to be injected, however the activation of the drug is non-invasive wherein light is delivered through the pupil.

Underpinning the need is the realization that selective illumination of a localized region of the eye at the equatorial peripheral sclera, where the eye has been provided with a crosslinking agent, can be used to treat and/or prevent myopia and its progression. Advantageously provision of a crosslinking agent does not have to be carried out with great precision as the induced crosslinking will be confined to the illuminated targeted eye region. Precise placement of crosslinker to avoid undesirable crosslinking occurring outside/remote from the specifically targeted region is not needed. The device thus enables convenient treatment or prevention of a myopia and associated pathologies such as retinal detachment, laquer cracks, staphyloma formation, myopic choroidal neovascularisation and/or myopic macular degeneration (MMD).

The device comprises a contact component preferably in the form of an opaque contact lens which is to be worn on an eye to be treated and which restricts all light entering the eye to light from the light guide apparatus/pipe which is oriented on the contact lens in a way that selectively targets light passing through the device to illuminate one or more regions of the equatorial peripheral part of the sclera. It will be understood that the device is used on an eye that has been pretreated with a crosslinking agent for protein (preferably collagen protein) crosslinking in the tissue illuminated by the light delivered by the device to the specific localised regions in the equatorial peripheral part of the sclera.

The contact lens is provided with an opaque light guide in this example in the non-limiting form of a light transmittable pipe (or funnel) (hollow in this example but this is not essential as the pipe (or funnel) may be filled or coated with a light transparent material) which is attached to the external face of the contact lens. The external face is the convex shaped side of the lens that faces outward away from the eye. The inner face is the concave shaped face which contacts to (and is dimensioned and curved to fit) the cornea of the eye. Suitably the device is connected and/or mounted on the lens in a way that that restricts light entering the eye to that travelling through the light pipe (or funnel) which is oriented on the device such the light is delivered to a localized and very specific predetermined area of the eye. Importantly, the light delivered is confined to that very specific predetermined area of the eye. Advantageously, the contact lens component of the device in use is attached to the cornea and so moves with eye movements thus eliminating the effect of unwanted movements and eliminates the need for a laser alignment system.

The inventors have found that use of non-collimated point light sources (such as LEDs) lead to diffuse and large patches of illumination which are not useful for exclusive selection or targeting of small regions of the inner eye. However, with the device of the invention as the light reaching the eye is collimated on passing through the light guide apparatus, it is concentrated to a particular target area of interest (one or more regions/areas in the equatorial peripheral part of the sclera) in the form of a much more narrow (less diffuse) light beam (or band of light) that is possible using prior art methods of light delivery to an eye/to the posterior sclera usually considered the target area of protein crosslinking and biomechanical strengthening.

The device of the invention thus advantageously provides light exclusively to one or more preselected/target regions/areas of the equatorial peripheral part of the sclera region to the eye where other regions beyond are not illuminated and thus do not experience crosslinking. This is a much safer approach than in prior art methods described above. It will be understood that collimated light is light in which the light rays are parallel and therefore will spread minimally as the light propagates as the ray do not diverge to any significant degree. This allows the very specific targeting of localised tissue areas/regions required by the present invention. Advantageously, this avoids unnecessary crosslinking in areas of the eye where crosslinking is not necessary or may even be undesirable. It also greatly minimizes risk of undesired crosslinking in other parts of the eye, e.g., the optic nerve head, even if crosslinking reagent is present at such other parts of the eye.

Advantageously, the device of the invention and particularly the light directing light guide/pipe (or funnel) feature allows the localized target area of the equatorial peripheral part of the sclera to be stimulated via illumination with a light beam of a defined shape and diameter at a specific predefined position/region. This involves specification of one or more of the following parameters: the location of the light guide/pipe base (or funnel apex) relative to the centre of the pupil; the light guide/pipe (or funnel entrance) diameter and/or shape, angle to the contact face, the length of the light guide light path through which light is transmitted through to the eye; and the light source brightness and availability of light to transverse through the light guide/pipe to impinge the cornea at the base of the light guide/pipe. Specifically, to target a specific depth within the sclera, the light will be applied at a pre-determined time relative to the diffusion time of the crosslinking agent previously applied in a pre-treatment step. Furthermore, the power of the light source, the length of time the lights source is on, and the frequency of light stimulation, will be manipulated so as to produce the desired degree of crosslinking.

An example of a device according to the invention is shown in Figure 13B,D. In this embodiment the device comprises a single long light guide/pipe located on the contact lens in a specific and predetermined position on the lens (relative to the center of the eye when worn) which is configured to selectively illuminate a region/area of the eye to be treated, that is the equatorial peripheral part of the sclera to which light is to be selectively delivered through the light pipe when the device is worn. This example of a device has been designed and tested on enucleated guinea pig eyes, and has been configured to allow local stimulation at the particular horizontal azimuth just below the equator of the eye globe of the enucleated eye. This region is believed to provide a new target for sclera tissue remodelling to treat a myopia as described elsewhere herein. However, the device of the invention can be configured to target any particular one or more additional localized region of an eye of any species of interest, particularly a human eye which can be of an adult, a teenager or a child. The particular targeted area of a guinea pig eye for the exemplary device of Figure 13D is shown in Figure 13E at the location of the yellow arrow (arrow on the most right) near the centre of the image. An image of the light spot taken from underneath the globe shows the posterior scleral surface (Figure 13E). The blue arrow (most left arrow) and corresponding line is at the limbus, while the dashed line and white arrow (middle arrow) is the equator, and the yellow arrow (most right arrow) shows the narrow bright spot of light obtained from stimulation with white light. It lies just below the equator.

Notably, this example of a device with a single pipe attached to the contact lens can be readily expanded to treat multiple areas such as by (i) rotation of the contact lens with the single pipe attached so that the light is directed to other target areas of interest; or (ii) installation of multiple pipes as shown in the further example in Figure 14A-D to illuminate multiple localized regions in the equatorial peripheral part of the sclera simultaneously.

Alternatively, a continuous narrow ring or partial ring of light can be achieved by projecting the light through a doubled sided hollow frustoconical cone shape as illustrated for the human eye in Figure 15.