Field of the invention

[001] The present invention relates to a surgical tool for eye surgery. In particular, the invention relates to a tool for assisting with the implantation of a toric intraocular lens (IOL) for correcting astigmatism, typically during cataract surgery.

Background of the invention

[002] Astigmatism commonly causes blurred vision for patients. It is usually due to an abnormality in the curvature of the cornea. This is referred to as corneal astigmatism. Corneal astigmatism is caused by differences in the radius of curvature in one principal meridian of the cornea compared to the other. These two principal meridians are located most commonly approximately at right angles to each other. One meridian is steeply curved (the steep axis) and the other meridian is less curved (the flat axis). To illustrate this difference, a soccer ball is spherical with equal radii of curvature. On the other hand a rugby ball has different radii of curvature. When light rays hit the steep meridian of an astigmatic cornea, they are refracted to a greater extent than the light rays which hit the flat meridian of the cornea. The light rays entering the cornea are then focused at 2 positions or planes inside the person's eye, instead of at a single point on the retina (the nerve-rich lining inside the eye which 'reads' the image received by the eye). Accordingly, the person's visual image is out of focus at the retinal plane. The result is that vision is generally blurred and this blurred vision can occur at short, intermediate and long viewing distances.

[003] Patients with corneal astigmatism usually require spectacles to overcome astigmatism, correcting the refractive error, and providing clarity of vision.

[004] Sometimes astigmatism may be corrected with contact lenses. However, many patients prefer good vision without the need to wear spectacles or contact lenses and, in order to achieve this, surgery may be required. In some cases of severe astigmatism, spectacles or contact lenses will not be sufficient to achieve good vision and surgery will be necessary.

[005] Corneal astigmatism can be improved by certain surgical procedures, such as refractive laser surgery and incisional corneal surgery. However, some patients have an aversion to undergoing surgery (unless essential) and any surgical procedure does involve some risks. Furthermore, the improvement in astigmatism, may be unpredictable with these procedures and unsatisfactory outcomes may occur. [006] If a patient with corneal astigmatism also has cataracts, and cataract surgery is required, this is generally an opportunity for the patient to have both problems rectified with a single surgical procedure. Cataract surgery involves replacing the cloudy lens of the eye with an intraocular lens (IOL). The surgical technique most commonly used for cataract removal is called Phacoemulsification Surgery or Small Incision Cataract Surgery. The procedure involves the removal of the cataract and the implantation of an IOL through a micro incision (less than 3 mm wide).

[007] An IOL is an artificial lens, usually formed of acrylic, silicone or PMMA

(polymethylmethacrylate), which has a similar shape to a natural lens. An IOL is designed to reside inside the eye and focus light on the retina. In modern cataract surgery, the chosen IOL inserted has a refracting power (dioptre), that will enable the patient to see clearly in the distance without spectacle correction. Spectacles are usually required for close vision. Some patients having cataract surgery, prefer to see clearly at close range without spectacles, and an IOL is inserted with an appropriate refracting power to achieve this outcome. These patients often require spectacles for distance vision. Other patients prefer to not wear spectacles for either distance vision or near vision, and multifocal IOLs can be inserted to achieve this. However, clear vision without spectacles for distance, near or intermediate vision, is not possible if a patient has significant corneal astigmatism, unless an IOL is chosen that also corrects for astigmatism (a toric 10L).

[008] Many cataract patients also have astigmatism that can now be corrected by surgery. Where a cataract patient also has an astigmatism, the astigmatism and the cataract can both be remedied during a single surgical procedure. There are several approaches to correcting astigmatism at the time of cataract surgery, including: incision placement on the steep axis of the cornea, single or paired peripheral corneal relaxing incisions (PCRTs) and toric IOL implantation.

[009] The methods of incision placement on the steep access and PCRTs have a number of undesirable complications, such as unpredictability of effect, insufficient effect, infection risk and more difficult surgery. Largely because of the unpredictability of effect, these procedures (if required) are usually performed as a subsequent procedure, at a later date to the cataract surgery. This requires a second episode of treatment which involves extra costs to the patient and to any health insurance providers. Another common criticism of these procedures is that the treating nomograms are complex and confusing. The incisions have to be adapted for age, location, and degree of astigmatism. As a result of such limitations, these methods are not generally preferred in the surgical treatment of corneal astigmatism in patients who also have cataracts.

[010] Another method to correct residual astigmatism after cataract surgery is laser assisted in-situ keratomileusis (LASIK) This method cannot be done at the time of cataract surgery. It is useful as a technique but the excimer laser treatment is expensive, involves a second episode of care and requires specialised expertise to obtain optimum results. Most cataract surgeons do not perform excimer laser treatment routinely in their practices.

[Oi l] Due to the above problems with alternative procedures, toric IOL implantation has become a preferred option for correcting corneal astigmatism in patients requiring cataract surgery. The toric IOL implantation procedure requires only minor adjustments to normal cataract surgical techniques. It generally provides favourable results in terms of unaided vision and involves relatively low risks. Also, the desirability of this procedure has recently been further enhanced by the availability of an increasing range of high quality toric IOLls. It is estimated that up to 50 per cent of cataract patients have astigmatism that can be corrected by the implantation of a toric IOL.

[012] In preparation for the implanting of a toric IOL in a patient's eye, careful measurements are made preoperatively to determine the patient's axis of corneal astigmatism (being the steep axis) and the magnitude of the astigmatism to be corrected. The angle of this axis and the magnitude of the astigmatism are recorded. The magnitude of the astigmatism will determine the type (i.e. toric power) of toric IOL which is to be implanted. The angle of the axis will be used to align the toric IOL in the correct orientation so as to overcome or ameliorate the effect of the astigmatism.

[013] Prior to commencing surgery, and before any periocular injectable anaesthetic or general anaesthetic is given to the patient, the eye to be operated on is generally marked in the following manner. With the patient sitting upright and looking straight ahead, the limbus at 0°, 90° and 180° (usually) is marked with a skin marking pen. These marks act as the reference points during surgery.

[014] During surgery, the toric IOL is inserted inside the capsule of the eye and it is then rotated to the correct axis of orientation. The toric IOL typically has 3 marking indentations at each hapticoptic junction. These marking indentations are aligned exactly with the steep corneal astigmatic axis, which can be in any axis from 0° to 180°. A particularly suitable toric IOL for use in the above procedure is the AcroSof™ toric IOL. This toric 1OL is an acrylic polymer that has ultraviolet and blue light filters and which has been FDA approved in the USA. [015] The intraocular alignment of the IOL is assisted by the use of an intraoperative toric axis guide instrument. Current toric axis guide instruments are formed of metal (typically stainless steel) and are re-usable. Examples of toric axis guide instruments currently in general use are the Mendez gauge, Dell marker and Nichamin instrument.

[016] These instruments are of similar design. They are somewhat spoon-shaped, typically consisting of an elongated handle at one end of which is a flat, annular- shaped ring having visible degree markings on an upper face of the ring. During surgery, the surgeon holds the elongated handle and the flat ring is placed on the patient's eye, with the cornea of the eye positioned centrally within the ring. The 45 0° and 180° markings on the upper face of the ring are aligned with the corresponding reference markings which have been previously made on the patient's eye.

[017] The toric axis guide instrument assists in determining the correct alignment of the toric IOL, which is rotated within the capsule of the eye, by the surgeon, until it is in exactly the correct orientation. To effect this, the toric IOL is typically rotated by the surgeon so that the marking indentations on the toric IOL align with the steep axis of corneal stigmatism (which has previously been determined).

[018] The abovementioned toric axis guide instruments suffer from a number of shortcomings. For instance, such toric axis guide instruments need to be sterilized between operations before they can be re-used. Proper sterilization procedures take some time and this therefore involves significant 'down time' for each instrument. Where only a single such marker instrument is available, substantial delays between operations can occur, thereby reducing the efficiency of the surgeon and limiting the number of patients that can be treated during a particular operating session. The toric axis guide instruments are quite expensive (hundreds of dollars) and, therefore, it is not common to have multiple toric axis guide instruments available in a surgery.

[019] The above toric axis guides are also quite cumbersome to use. The surgeon holds the toric axis guide by grasping the elongated handle with one hand. A right handed surgeon would typically hold the handle of the axis marker in the left hand to check orientation and rotate the IOL with the right hand (and vice versa if left handed). Due to the length of the handle (which is similar to the length of a tea spoon), the surgeon's hand is some distance away from the surface of the eye on which the annular-shaped ring is placed. This distance makes it somewhat awkward for the surgeon to control movement of the annular-shaped ring with high precision. [020] The above toric axis guides also have a tendency to break at the weak point where the annular-shaped ring joins the elongated handle. Once broken the instrument is rendered useless, as it often cannot be repaired.

[021] The present invention is directed towards ameliorating some of the problems identified above. More particularly, the present invention is directed towards a convenient surgical tool for use during toric IOL implantation surgery to facilitate the alignment of the toric IOL with the patient's axis of corneal astigmatism.

[022] Any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates, at the priority date of this application.

Summary of the invention

[023] According to this invention, there is provided a surgical tool, for aligning a toric intraocular lens with an axis of corneal astigmatism of a patient, said tool including: a lower surface adapted to abut a patient's eye; an upper surface showing angle markings; a finger engagement surface, having a height of at least about 0.5 cm, adapted to be held by fingers of a surgeon when using the surgical tool; and eye viewing means through which the patient's eye can be viewed, wherein said angle markings are positioned so that, when said lower surface abuts a patient's eye, the angle markings are adapted to be located substantially about the limbus of said patient's eye and no more than about 0.3 cm above said limbus.

[024] As would be apparent to those skilled in the art, the limbus of an eye is the circumferential junction between the cornea and the sclera of the eye.

[025] The main reason for requiring that the angle markings are located within about

0.3 cm of the limbus of the patient's eye is so as to reduce the potential for parallax error which may otherwise occur if the distance between the markings and the limbus is greater. Accordingly, the abovementioned distance of about 0.3 cm or less between the markings and the limbus should be regarded as a preferred feature, not an essential one.

[026] Preferably, the finger engagement surface includes engagement enhancement means. The purpose of the engagement enhancement means is to improve the surgeon's finger grip of the surgical tool and thereby reduce the likelihood that the tool will slip or be dropped during use. The engagement enhancement means are typically selected from one or more of a ribbed surface, a roughened surface, a large surface area, and finger accommodating curves. It will be appreciated, however, that numerous other engagement enhancement means could be used for this purpose.

[027] The finger engagement surface may simply be a peripheral surface of the surgical tool. As will be apparent, the height of the peripheral surface will need to be sufficient for the surgeon conveniently to be able to grasp the tool with the ends of his or her fingers. The peripheral surface can have any number of cross-sectional shapes. However, preferred cross- sectional shapes include circular, octagonal, heptagonal, hexagonal and pentagonal. Alternatively or in addition to the above, the peripheral surface may have straightened or indented sections for being engaged by the fingers of the surgeon.

[028] In one preferred embodiment of the invention, at least a portion of the peripheral surface extends upwardly from a peripheral portion of the upper surface. In a particularly preferred embodiment, the peripheral surface includes two or (more preferably) four portions which extend upwardly from the peripheral portion of the upper surface. These upwardly extending portions of the peripheral surface are preferably located equidistant from each other. As will be apparent, these upwardly extending portions constitute finger engagement surfaces which are adapted to be engaged by the fingers of the surgeon.

[029] The eye viewing means can include a transparent plastic disk (or film) and the upper surface and lower surface are formed on opposed sides of the plastic disk (or film). In this embodiment, the surgical tool may be formed entirely of a transparent plastic. If the disk is transparent, the angle markings could obviously be located on the upper surface, on the lower surface or anywhere in between.

[030] Alternatively, the eye viewing means can simply be a hole extending from the lower surface to the upper surface. In this embodiment, the angle markings are preferably located adjacent to the hole. The hole is preferably dimensioned so that, at least, the cornea, iris and limbus of the patient's eye are visible when the surgical tool is placed upon the patient's eye. Typically, the hole has a diameter of between about 8 mm and 25 mm. Preferably, the diameter of the hole is between about 10 mm and 20 mm. A particularly preferred diameter of the hole is about 13 mm. It is particularly preferred that the circumference of the hole is dimensioned so that it is substantially the same as or slightly greater than the limbus of said patient's eye. In the region of the hole, the upper surface may taper down towards the lower surface so that, when the tool is in use, angle markings located on the upper surface are very close to the limbus of the patient's eye, thereby minimising the potential for parallax error. These features make the alignment of the angle markings with pen markings previously made on the patient's eye more accurate and reliable.

[031] The angle markings on the upper surface of the surgical tool preferably include markings at 0°, 90°, 180° and 270°. In a further preferred embodiment, the tool further includes markings at 45°, 135°, and 315°. hi a particularly preferred embodiment, the upper surface of the surgical tool has angle markings at 5° or 10° intervals between 0° and 360° (or from 0° to 180° and from 180° to 0°).

[032] The lower surface and the upper surface of the tool are preferably on opposed sides of a disk having a thickness of less than about lcm (10 mm). The thickness of the disk is preferably less than about 0.5cm (5 mm). Having a thin disk can help reduce the possibility of parallax error which would otherwise occur if there is a significant distance between the angle markings and the limbus of the patient's eye. As is apparent from the above, the disk is generally annular-shaped (although the outer perimeter of the disk need not be circular-shaped)

[033] In a preferred form of the invention, the lower surface of the surgical tool may be contoured, or at least include a contoured portion, so as to substantially conform with the contour of an eye.

[034] The surgical tool described above can be formed of any suitable material. A particularly preferred material is polymeric or plastic as it is cheap, light and easy to use. By forming the surgical tool of plastic, the tool is able to be made inexpensively and therefore the tool can effectively be disposable. This enables a surgery to stock a multitude of the surgical tools described herein. A significant benefit of this is that no time needs to be wasted in sterilizing the tool in between operations on different patients. A new surgical tool can readily be used for each patient. More patients can then be treated in a single operating session, thereby improving the efficiency of the surgeon and the operating theatre.

Brief description of the drawings

[035] An embodiment or embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[036] Figures Ia to Id are top plan views of surgical tools according to preferred embodiments of the present invention.

[037] Figure 2 is a top perspective view of the surgical tool shown in Figure Ia.

[038] Figure 3 is a top perspective view of the surgical tool shown in Figure Ic. [039] Figure 4 is an end view of the surgical tool shown in Figure Ic and Figure 4.

[040] Figure 5 is a bottom plan view of the surgical tool shown in Figure Ic and Figure

4.

[041] Figure 6 is a top perspective view of a surgical tool according to an alternative embodiment of the invention.

[042] Figure 7 is a top plan view of a surgical tool according to a preferred embodiment of the present invention.

[043] Figure 8 is a bottom plan view of the surgical tool shown in Figure 7.

[044] Figure 9 is a top perspective view of the surgical tool shown in Figure 7.

[045] Figure 10 is a bottom perspective view of the surgical tool shown in Figure 7.

[046] Figure 11 is a schematic, cross-sectional view showing the surgical tool of a preferred embodiment of the present invention abutting the eye of a patient.

[047] Figure 12 is a top perspective view of the surgical tool according to another preferred embodiment of the invention.

[048] Figure 13 is a top perspective view of a surgical tool according to another alternative embodiment of the invention.

[049] Figure 14 is a top perspective view of a surgical tool according to another alternative embodiment of the invention

Detailed description of the embodiment or embodiments

[050] The invention described above will now be illustrated by reference to the preferred embodiments shown in Figures Ia to Id and 2 to 14.

[051] As shown in several of the figures including Figure 2, Figure 3, Figure 6, Figure 9 and Figure 12, preferred embodiments of the surgical tool of this invention include an upper surface 1, a finger engagement surface 2 and a hole 3 which extends through the tool. As shown in these figures, the upper surface 1 includes angle markings 4, being markings showing angles between 0° and 180° (and, effectively, numerous other angles between 0° and 360°). In the embodiment shown, the angle markings 4 are each spaced apart by 5 or 10°.

[052] As shown in Figures 13 and 14, it is not always essential that these angle markings are located on the upper surface of the surgical tool. For instance, if the tool is formed of a transparent material, the markings could be located on the lower surface, on the upper surface or anywhere between these two surfaces.

[053] In the embodiment shown in Figure 2, the finger engagement surface 2 extends around the perimeter of the tool between the upper surface 1 and a lower surface (not shown). The finger engagement surface 2 includes two end sections 5 which are substantially flat and which are, thereby, more readily adapted to be engaged by the fingers of a surgeon using the tool.

[054] Figures Ia to Id and Figure 7 show upper surfaces 1 of several alternative embodiments of the subject invention. As can be seen, these upper surfaces are similar to one another. The upper surface 1 of Figure Ia is the same as the upper surface shown in Figure 2. The upper surfaces of Figures Ib and Id include two diametrically opposed projecting points 10 at the 0° and 180° markings. The upper surfaces shown in Figures Ib, Ic and Id have diametrically opposed pointed indentations 11 at the 0° and 180° markings.

[055] The finger engagement surface 2 of the tool shown in Figure Ia includes two diametrically opposed flat sections 5a for facilitating the finger clasping of the tool by the surgeon. The finger engagement surfaces of the tools represented in Figures Ib and Ic show concave end sections, 5b and 5c (respectively), which are shaped so as to more comfortably and effectively engage with the fingers of the surgeon. Although the flat sections 5a and the concave end sections, 5b and 5c, are depicted in Figures Ia, Ib and Ic as being located adjacent the 90° and 270° markings, these sections may alternatively be located adjacent to the 0° and 180° markings. In another alternative embodiment of the invention, the tool may have the same or similar flat sections or concave sections at each of the 0°, 90°, 180° and 270° markings. As further alternatives, and as noted previously, the perimeter of the tool may have a cross sectional shape which is octagonal, heptagonal, hexagonal or pentagonal.

[056] Figures 3 and 4 show a surgical tool in which the finger engagement surface 2 has end sections 5d which are substantially flat and which are significantly wider than the rest of the finger engagement surface. These end sections 5d also have a set of parallel ribs 51. The increased width of the end sections 5d and the inclusion of the parallel ribs 51 enhance the grip which a surgeon is able to achieve when holding the surgical tool in his or her fingers.

[057] As shown more clearly in Figure 5, Figure 8 and Figure 10, the lower surface 6 of the surgical tool includes a contoured portion 7 which is contoured so as to substantially correspond with the contour of a patient's eye. This enables the surgeon to locate the surgical tool on or very near to the patient's eye when checking on the alignment of the toric IOL which is being (or has been inserted) into the patient's eye. A particular benefit of this is that it enables the angle markings on the surgical tool (e.g. on the upper surface 1) to be very near to the surface of the patient's eye. This reduces the possibility of parallax error when determining the correct angle for properly aligning the toric IOL in the patient's eye. Another benefit of the contoured portion 7 is that it avoids any sharp edges being present in the lower surface 6 which could otherwise damage the eye.

[058] The surgical tool shown in Figure 6 has a finger engagement surface which consists of a continuous wall 20 which extends upwardly from a periphery of the upper surface 1 of the tool. Such a wall provides a large surface area for the surgeon's fingers to grip and which is more easily rotated by the surgeon's fingers. The upper surface 1 and the angle markings 4 thereon are clearly visible when looking down through the continuous wall 20. To further enhance the surgeon's vision, the continuous wall could be tapered outwardly as it extends upwardly so that the circumference of the wall is greater at the top than it is adjacent to the upper surface 1. The continuous wall 20 may be circular in cross-section or it can have any other suitable cross-section.

[059] The continuous wall 20 shown in Figure 6 is substantially circular but it has two flat sections 21 for enhancing engagement with the fingers of the surgeon. These flat walls 21 are preferably located adjacent the 0° and the 180° markings (or adjacent the 90° and 270° markings).

[060] The surgical tool shown in Figure 7, Figure 8, Figure 9 and Figure 10 has four finger engagement portions 5e extending upwardly from the upper surface of the tool (and which are more clearly shown in Figures 9 and 12). These upwardly extending finger engagement portions 5e are located equidistantly about the perimeter of the tool. In the embodiment shown, these four upwardly extending finger engagement portions are located in line with the 0°, 90°, 180° and 270° markings.

[061] Figure 11 shows (in cross-section) a surgical tool according to this invention abutting the eye 10 of a patient. As can be seen, a contoured portion 7 of the lower surface 6 of the tool may rest against the eye (which may be preferred in order to take accurate measurements with the tool).

[062] The surgical tools shown in Figures 13 and 14 are formed of transparent plastic material. Accordingly, the angle markings 4 can be located on the upper surface or on the bottom surface 6 (as shown in Figure 14) or somewhere intermediate the upper and lower surfaces (as shown in Figure 14). [063] Where ever it is used in the specification and claims, the word "comprising" is to be understood in its "open" sense, that is, in the sense of "including", and thus not limited to its "closed" sense, that is the sense of "consisting only of. A corresponding meaning is to be attributed to the corresponding words "comprise", "comprised" and "comprises" where they appear.

[064] It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text. AU of these different combinations constitute various alternative aspects of the invention.

[065] While particular embodiments of this invention have been described, it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive, and all modifications which would be obvious to those skilled in the art are therefore intended to be embraced therein.