The present invention relates to a field of microscope to support a surgeon performing a surgical eye treatment and more particularly it relates to an illumination system for surgical and other stereo microscope for enhancing the red reflex glow and stereoscopic view for increasing the surgical efficiency by achieving coaxial beams of light which gives excellent red glow, depth of focus and high resolution and provides an economical and efficient solution for enhancing quality of cataract surgery.

BACKGROUND OF THE INVENTION

The microscopy system is configured to provide an appropriate illumination for a treatment of a region of the eye, such as a cornea, an iris, and a lens of the eye. A stable red reflex, depth of focus and resolution are the most important features of an ophthalmic surgical microscope for cataract surgery. It's the red reflex that makes the structure of the lens and its fibers prominently visible against the red background, and thus makes for a uncompromised view for a successful and secure clean surgery. One of the challenges with visualization is enhancing the red reflex and stereopsis particularly during phacoemulsification, cataract extraction and also during the intraocular lens implantation surgery.

However, conventional red reflex illumination often decreases during the critical phases of the procedure like phacoemulsification. Further, there is lack of stereoscopic view in a procedure like phacoemulsification. Phacoemulsification is a procedure in which the lens clouded by a cataract is broken up by ultrasound, irrigated, and suctioned out. It is known that, eye surgery is an intricate procedure, which requires a lot of meticulousness and attention, while the surgery is under progress, and also, in terms of post-operative care. However, it is also pertinent to note that, if the surgery is performed in an efficient manner, the outcome of the surgery is excellent, and the expected results are achieved. The excellent outcome of the surgery lies not merely in the dexterity of the eye surgeon, but also, in the instrumentation and medication deployed, for conducting the surgery. Since, the eye tissue is very delicate structure - organ and limited space for surgery involves observing the eye under a microscope, and concurrently performing the surgery in conjunction with an stereoscopic illumination system.

Illuminating device for surgical microscope mostly use for illumination a light path which forms only a small angle with the observing beam path. This is important, for example, when it is desired to observe deeper lying regions during an operation. If the illumination is not approximately parallel to the observing beam path, the constant red reflex from the retina of the eye is not achieved.

In eye surgery, the illumination in an ophthalmic surgical microscope must often meet special requirements. For example, in cataract surgery, illumination systems are used which illuminate the patient's eye in such a way that the illumination beam path extends substantially coaxially with the observation beam path of the surgical microscope. This produces the so-called red reflex, in which the light beam reflected back from the retina causes the pupil of the patient's eye being operated on to shine with a reddish light. This red reflex illumination is advantageous, particularly in cataract surgery, because residual tissue, which may be left after the removal of the eye lens from the lens capsule and has to be removed to avoid complications, can be detected particularly easily against the backlight provided by the red reflex.

Conventionally, various kind of development had been imparted for illumination system in ophthalmic microsurgical procedures. Such an illumination system has been disclosed in patent document US5760952. Said document discloses an illuminating device for a surgical microscope, which device has a light source arranged outside the observing beam path, a first deflector for light arranged between the light source and the observing beam path of the microscope, and a second deflector for light arranged closer to the observing beam path than the first deflector, is distinguished in that the first deflector comprises two deflecting elements of which one is fixed and the other is movable, and of which the deflecting element arranged closer to the observed object is also provided with a deflecting device on its side averted from the light source for directing light from the other deflecting element to the second deflector.

This known illuminating system for operation microscopes has the disadvantage that for the divided microscope principal objective intended for this microscope, a new optical construction series is necessary, and that, strictly speaking, it constitutes a paraxial illuminating system, rather than a truly coaxial system.

The arrangement in aforesaid patent document is functional but does not provide illumination of the treatment area coaxially with the viewing paths. This is not usually a problem for anterior superficial structure treatments of the eye since the illumination adequately illuminates the treatment area. For posterior deeper structure treatment areas there is a problem since the optical path for the treatment and viewing must pass through the aperture created by the iris. The angles are such that for treatment of the posterior of the eye virtually coaxial delivery of the illumination and viewing is required. This is not possible with the arrangement disclosed by US5760952.

Further, generating the red reflex and maintaining the red reflex during the surgical treatment, especially when the eye is moving, or the lens is changed, is often involving a considerable effort. Further attention has to be paid that for protection of the retina of the eye an intensity of the illumination has to be limited so that the red reflex cannot always be generated with the desired intensity.

In order to overcome above limitation, various attempts have been made heretofore. However, due to complex arrangement of lens and number of light source, they are comparatively expensive and complex in construction. OBTECT OF THE INVENTION

The main object of the present invention is to provide an illumination system for an ophthalmic surgical microscope for enhancing the red reflex glow for increasing the surgical efficiency by achieving collimating coaxial beams of light which gives excellent red glow, depth of focus and high resolution and provides an economical and efficient solution for enhancing cataract surgery. Further object of the present invention is to achieve great depth of focus and clarity by enhancing red reflex glow during eye surgery.

Another object of present invention is to provide an improved coaxial illuminating system for operation microscopes, of simple construction and so designed that it can be constructed to existing conventional ophthalmology microscopes without necessitating the use of a second illumination source.

Yet another object of the present invention is to provide a simple effective oblique and coaxial illumination system for an ophthalmology microscope in order to minimize light induced retinal damage.

Yet another object of the present invention is to provide an illumination system for an ophthalmic surgical microscope capable of being adjusted for use at different microscope focal lengths. Yet another object of the present invention is to increase illumination and field of illuminated area with or without iris mechanism.

Yet another object of the present invention is to provide an illumination observation system that is easy to operate, inexpensive in its design, and at the same time offers superior observation properties.

SUMMARY OF THE INVENTION

The present invention relates to an illumination system (1) for surgical and stereo microscope for enhancing the red reflex glow for increasing the surgical efficiency by achieving coaxial beams of light which gives excellent red glow, depth of focus and high resolution and provides an economical and efficient solution for enhancing cataract surgery. In present invention, the light beems generated by the light source is travelled through the Plano convex lens to produce four collimated light beams, one from each quadrant of the lens, as each quadrant refracts like a prism. Said collimated lights are directed downwardly at 90° towards the objevtive lens. Focused beam then passed through the objective lens. By passing through the objective lens, said beams partially overlap eachother producing stereoscopic illumination. In present invention, the collimated light beams are coaxial with the light transmitted to the binoculars. BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings. Fig. 1 illustrates a schematic view of a stereoscopic ophthalmic microscope with illumination system position between objective lens and binocular according to an exemplary embodiment of the present invention.

Fig. 2 illustrates a schematic view of different position of the light source according to present invention.

Fig. 3(a) and Fig 3(b) illustrates a schematic view of the images achieved by focus (A), pre-focus (B) and post focus(C) according to present invention.

Fig. 4 illustrates a schematic view of an illumination system totally overlapping all four images created by all four quadrants of the Plano convex lens, according to an exemplary embodiment of the present invention.

Fig. 5 illustrates a schematic view of an illumination system superimposing all four images, according to an exemplary embodiment of the present invention. Fig. 6 illustrates a schematic view of a stereoscopic ophthalmic microscope with illumination system between objective lens and subject surface, according to another embodiment of the present invention. Fig. 7 illustrates a schematic view of a stereoscopic ophthalmic microscope with spared (9) of microscope illumination system according to another embodiment of the present invention.

It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are generally represented by like reference numerals for illustrative purposes throughout the figures. It also should be noted that the figures are only intended to facilitate the description of the preferred embodiments. The figures do not illustrate every aspect of the described embodiments and do not limit the scope of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompanied drawings. The invention is capable of other embodiments, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation. It is to be also understood that the systems of the present disclosure can be used in any field but are especially useful in surgical settings or any other application in which highly three dimensional objects require magnification, particularly those partially occluded by an enclosure. An example of this is ophthalmic surgery.

The present invention provides an illumination system (1) providing good stereoscopic effect in the red reflex light from patient's eye during deeper ophthalmic surgery and capable of reducing the risk of photo-toxicity.

The invention is an illumination system (1) for a microscope. The invention contains illumination system being the stereoscopic system which delivers beams of collimated light (as defined herein) to the subject surface (3). These beams of collimated light overlap on the subject surface (3) at least partially. The advantage of the stereoscopic collimated light is a better three dimensional view than produced by prior art illumination systems under similar circumstances. Compared to uncollimated light, delivering collimated light into a partially occluded opening allows (a) greater quantity of light and (b) more direct light. The at least partial overlap of the collimated light allows the user viewing through binoculars (2) to view the subject surface (3) optimally with stereopsis (10).

It is to be also understood that the invention can be installed into an entire microscope or can be constructed as a module fitting onto an existing microscope. If constructed as a module, the module includes an objective lens (7) that replaces the objective lens (7) of the microscope or can be constructed between the objective lens and subject surface. The construction of the microscope may be altered substantially without affecting the illumination system (1).

It is to be also understood that the illumination system (1) according to present invention is used in ophthalmic as well as compound microscope. Further, said illumination system (1) is also capable of being used in ophthalmic surgery as well as other field of surgery where three dimensional effects is highly demanded.

First, the design and function of an illumination system (1) in a microscope according to present invention is explained with reference to FIG. 1. Now, as illustrated in Fig. 1, a stereoscopic ophthalmic microscope with illuminating system (1) according to present invention comprises a binocular head (2) wherefrom the surgeon can observe a subject surface (3) i.e. tissue under examination in a surgical procedure., an adjustable light source (4) for emitting stereoscopic and collimated light beams, an aspheric or aspheric-achromatic Plano convex lens (5) consisting positive focal length elements that have one spherical surface and one flat surface, a beam splitter (6) for reflecting collimated light downward to the subject surface (3) through an objective lens (7) located between beam splitter (6) and the subject to produce four beams on the eye. The portion of the light from the collimated beam of light passing from the beam splitter (6) is absorbed by a non-reflective light absorber (8). In preferred embodiment, the beam splitter (6) transmits some of incident light and reflects remaining of the incident light. The function of the beam splitter (6) is to allow light to pass upward from the subject surface (3) to binocular for observer. Said embodiment produces collimated light beams for stereoscopic light beams by passing light through the Plano-convex lens (5) positioned at the appropriate focal plane. The collimated light beams are coaxial with the light transmitted to the binoculars (2).

Said Plano Convex lens (5) is an optical element which is a refractive lens having a positive focal length, i.e., a positive lens (5). Such a lens (5) collects illumination from light source (4) and projects on beam splitter, reflecting it to the objective lens (7) which transmits the illumination beams on subject surface (3). From which the beams are reflected towards the binocular co-axially.

The optical convex lens is having a special property, each of the four quadrants (PI, P2, P3, P4) behaves like a prism. So, one Plano convex lens gives four prism images when single collimated beam is refracted. All the images from each quadrant prism are superimposed by conversing to each other at the focus point, thus a bright single images produce.

In pre focus condition all four images by quadrant prism are specially overlapped and in the center of the pre focus condition all four images are overlapped.

In post focus condition of the images are crossed overlapping so that right margin of image is made by left side image and vice versa. So the same for below and above margins. This is a special property of convex optical lens used to get four images converging to overlap each other, partially, (pre focus), completely (focus) and crossed overlapping (post focus).

The images right and left, above and below are observed through binocular microscope by observer from different angle, creates stereoscopic view of subject surface.

It is to be understood that said light source may be white LED (4) or any other suitable light source. Further, said Plano convex lens (5) is positive focal length element that has one spherical surface and one flat surface. Said Plano convex lens (5) collimates diverging beams and to apply focus to a more complex optical system. Further, the infrared filter and ultraviolet filter (not shown) are also placed any convenient position in pathway between the light source (4) and the subject surface (3). A cooling fan is fitted for LED (4) if required.

In embodiment shown in Fig. 1, said collimated light reflected from the beam splitter (6) downward to the subject surface (3) overlap each other at least partially at the stereoscopic illumination through the objective lens (7). Due to said configuration, collimated light beams illuminating the subject surface (3) i.e. eye and reflected light beams from the retina as red reflex, travelling through the objective lens (7) towards the binocular (2). Further, said adjustable light source (4) allows orientation of the illumination beam path to be adjusted relative to an observation beam path of the surgical microscope so as to obtain a red reflex and stereopsis.

Now, as illustrated in Fig. 2, there is shown different positions of the adjustable light source LED (4) for achieving an image in full high definition (HD) directly into the eyepieces of a surgical microscope as per surgeon's requirement. Said light source (4) is movable in to and fro according to the focal length of the objective lens (7) to get desired image (focus (A), pre-focus (B) and post focus (C) as shown in Fig. 3a and 3b). According to the requirement, the surgeon may adjust the position of LED (4). The intensity and width of the illumination are changed inversely proportional on subject surface by moving the LED to and fro horizontally. However, alternate attachments are rheostat and iris mechanisms are constructed in microscope to adjust intensity and width of illumination on subject surface. Further, in present invention, by moving light source up and down angularly, the oblique light is achieved when red reflex is not required during the surgery.

Now, as shown in Fig. 4 and 5, the single light source LED is projecting light beams on the Plano convex lens producing four collimated light beams from each quadrant of the Plano convex lens. Thus, one collimated light beam gives four beams through the Plano Convex lens (5). These four collimated beams are reflected from the beam splitter and through the objective lens onto the subject surface and reflected partially collimated coaxially to the visual axis of the observer through the binoculars of the microscope. Referring continuous with Fig. 4 and 5, said beams converging to each other and overlap through the objective lens (7). This configuration gives constant and in all direction of eye positions the brilliant red glow with stereopsis (10). Said configuration also gives 3 dimensional stereoscopic view at focus, pre focus image and post focus images. Thus, at least partial overlap of the collimated light allows the user viewing through binoculars (2) to view the subject surface (3) optimally with stereopsis (10).

Thus, the reflection system and lenses used in the present invention ensure that the rays projected on objective lens (7) are converged on the eye on which the cataract surgery is to be carried out, thereby enhancing the "Red reflex" intensity causing increase in the success of the surgery as brilliant stereopsis (10) effect is obtained due to reflected beams are co axial to the observer's visual axis through the binocular.

Now, another embodiment according to present invention is shown in Fig. 6. In Fig. 6, it is seen that objective lens (7) is positioned between the binocular head (2) and the beam splitter (6). In this embodiment, the light source (4) is configured to produce converging rays that reflect downward on to the subject surface (3). In this configuration, the rays are converged and define the area of stereopsis (10), Said converged rays overlap each other on subject surface and reflecting from the subject surface (3) travel partially collimated and co- axially to the binocular gives, a superior stereoscopic view and the red reflex in the observed eye in operation. Fig.7 illustrates another embodiment of the stereoscopic ophthalmic microscope with illumination system (1) according to present invention. According to this embodiment, an additional illumination system (1) at an angle oblique to the stereoscopic system is also provided, but the light for the oblique system need not be collimated. In this embodiment, an oblique light (9) source is provided within the microscope or of the existing microscope for generating an oblique light beam.

The illuminating system (1) according to the invention provides overall four incident-light, converging beams from different angles simultaneously. The illuminating light of which, by reflection from the retina, provides a combination of a red reflex and stereopsis. This measure makes it possible to provide simultaneous illumination from different angles, also known as stereoscopic illumination. The illumination system according to present invention is used for the construction of a new ophthalmic microscope or as module, retrofitted in ophthalmic microscope either between objective lens and binocular or between objective lens and subject surface.

The invention has been explained in relation to specific embodiment. It is inferred that the foregoing description is only illustrative of the present invention and it is not intended that the invention be limited or restrictive thereto. Many other specific embodiments of the present invention will be apparent to one skilled in the art from the foregoing disclosure. All substitution, alterations and modification of the present invention which come within the scope of the following claims are to which the present invention is readily susceptible without departing from the spirit of the invention. The scope of the invention should therefore be determined not with reference to the above description but should be determined with reference to appended claims along with full scope of equivalents to which such claims are entitled.

Reference Numerals list

1. Illumination system

2. Binocular head

3. Subject surface

4. LED

5. Plano- convex lens

6. Beam splitter

7. Objective lens

8. Non reflective light absorber

9. Oblique light of microscope

10. Area of stereopsis

A. Focus

B. Pre-focus

C. Post-focus