WO2007107738A1

WO2007107738A1 - Improvements in and relating to optical devices

Info

Publication number: WO2007107738A1
Application number: PCT/GB2007/000976
Authority: WO
Inventors: Ernest Mark Talbot
Original assignee: Ernest Mark Talbot
Priority date: 2006-03-18
Filing date: 2007-03-19
Publication date: 2007-09-27
Also published as: GB0605445D0; GB2436068A

Abstract

There are provided optical devices (10) for use in eye surgery, said devices comprising a transparent material having a first concave surface (11) for interfacing with a cornea and a second opposed surface (12) for providing an air interface. Also provided are methods of use of such devices.

Description

IMPROVEMENTS IN AND RELATING TO OPTICAL DEVICES

FIELD OF INVENTION

The present invention relates to optical devices and to methods of use thereof.

BACKGROUND TO THE INVENTION

Operations to correct eye defects such as cataracts are well known. In order to perform such operations a surgeon must have a clear view of the area of the eye upon which he is working.

In normal circumstances the air-cornea interface is the place where light is most powerfully focussed (bent or refracted) by the eye. Imperfections at this interface can have a detrimental effect on image formation, whether as the patient sees the outside environment or as a surgeon sees the eye. It would thus be desirable to provide a means of improving optical viewing conditions to make surgery safer.

Accordingly, the present invention aims to address at least one disadvantage associated with the prior art whether discussed herein or otherwise.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an optical device for use in eye surgery, said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed surface for providing an air interface, wherein said device has, in air, substantially no focussing power.

Suitably, said second surface comprises a convex surface. Suitably, the second surface is not flat or concave.

Suitably, said first and second surfaces have opposed focussing (optical) powers of substantially equal magnitude .

Suitably, said device has sufficient thickness it can prevent fluid pooling over a region of a cornea covered by the device in use .

During anterior segment surgery, such as cataract and glaucoma operations, a fluid infusion is usually employed to keep the eye inflated and specifically to maintain the anterior chamber of the eye . An adverse event can occur when this fluid misdirects into the subconjunctival space causing the conjunctiva to inflate like a balloon. With the patient lying flat, this causes fluid to pool, in the valley between ballooned conjunctiva and convex cornea., This can be to such an extent that the normal curve^' of.,the air-cornea interface is replaced by a flat reflective fluid surface which no longer has the same focussing power as the air-cornea interface. Consequently, ^'surgical view may be lost and the surgery may not be completed. Alternatively it may be necessary to cut the conjunctiva to alleviate this pooling.

The present inventor has appreciated that such cutting of the conjunctiva may be ineffective or only partially helpful . . This may result in continuation of surgery under sub optimal viewing conditions.

The present inventor has appreciated that rather than removing fluid from the cornea surface it may be sufficient simply to displace it and provide a new air/optical interface, above the fluid level, which is equivalent to the air/cornea interface.

WOOO/02080 discloses a surgical contact lens. However, this document is directed towards a lens, principally for use in vitreo retinal surgery concerned with structures at the back of the eye, which has a focussing effect and alters the surgeons view of the eye. Such lenses are however not intended to displace fluid which has pooled due to conjunctiva inflation.

The present inventor has discovered lenses described in WOOO/02080 are not suitable for anterior segment surgery.

The present inventor has appreciated that it is surprisingly beneficial for a device for displacing .fluid to be configured such that it doe^'s not have fOcussing properties. The present inventor has appreciated that it is surprisingly beneficial for a device for displacing fluid to be configured such that a first concave surface interfaces and neutralises the corneal surface, and a second opposed convex surface provides an air interface . The second surface has curvatures comparable to the normal cornea. The mean magnitude of the power of each surface of the optical device are substantially equal and opposite . EP1364632 discloses a contact lens for use in laser surgery. However, the lens is specifically tailored for laser surgery and is intended to cause the curvature of the anterior surface of the cornea to conform with posterior surface of the lens. The lens also has a thickness of around 0.2mm which would not be great enough to prevent liquid pooling over the lens during anterior segment surgery.

US6224211 discloses lenses for achieving enhanced visual acuity. To determine a suitable lens for correction of the sight this document suggests the use of lenses having no refractive power at the vision axis. However, such lenses are only described as being of uniform thickness near the axis and so would cause undesirable distortion for anterior segment surgery. Further, liquid pooling is not a problem addressed by this document.

In addition to the above problems, other factors affecting the air-cornea interface may result in sub optimal viewing conditions for a surgeon. These may include if the surface of the cornea is: irregular in curvature;. irregular in surface texture and/or wetting; scarred; and/or obscured with blood. The device may suitably compensate for one or more of such factors.

As used herein,, by the term "transparent" it is meant a device which does not significantly degrade,- the optical detail normally seen. Thus the device need not transmit 100% of visible light, whilst a transmission of 90% or more may be desirable a transmission of 50% or greater may be sufficient for the devices intended use. Suitably, the optical device has substantially no effective focussing/refractive power.

Suitably, the optical device has a focussing power of no more than +/- 5 dioptres, suitably, no more than +/- 2 dioptres, for example no more than +/- 1 dioptre.

Suitably, the first and second surfaces have opposed focussing/refractive powers having mean magnitudes lying within 5% of one another, for example within 2% of,, one another.

Suitably, the first and second surfaces have opposed focussing/refractive powers having magnitudes lying within 2 dioptres of one another, for example within 1 dioptre of one another .

Suitably the first surface forms a portion of a sphere. Suitably, the first surface has a radius of curvature similar to that of a cornea of an eye with which the device is arranged to be used. Suitably, the second surface forms a portion of a sphere. Suitably, the second surface has a radius of curvature similar to that of a cornea of an eye with which the device is arranged to be used.

The first and second surfaces may each form portions of a sphere. The first and second surfaces may each have radii of curvature similar to that of a cornea of an eye with which the device is arranged to be used. Suitably, the first surface . is arranged to substantially conform to the anterior surface of the cornea during surgery.

During surgery the cornea may be distorted, for example by entry of a probe into the eye. The cornea may be distorted to have a parabolic form in cross section. Thus, if the first surface of the device is spherical it may not mate with the cornea as well as if it matched the distorted form of the cornea. A better interface of the device and the cornea may make the device more stable and may reduce the likelihood of air breaking between the device and the cornea which would impair surgical view. The device may thus have a first surface having a curvature arranged to substantially correspond to that of a distorted cornea. The first surface may thus be aspherical .

The second surface may have a curvature substantially corresponding to that of the ■ first surface.

Alternatively, the first surface . may be arranged to¹ mate with a distorted cornea and the second surface may be substantially spherical. The second surface may thus be .a representation of the undistorted cornea. In this^" case the device may have some focussing power which is suitably constrained to be minimal .

Suitably, in use, the optical device provides an improved optical view of front structures of the eye. Suitably, the device is arranged for use in anterior segment eye surgery. Suitably, the optical device lifts the effective interface of the eye with air, the air interface being at the second surface of the device rather than at the cornea surface. The device may enhance optical conditions for viewing anterior segment structures, for example by neutralising the effect of corneal imperfections and/or by creating an air interface that is raised above adverse factors such as infusion fluid pooling and/or fluid flow and/or ballooned conjunctiva and/or bleeding onto the cornea.

Suitably, the optical device is sufficiently thick to rise above fluid and/or debris interference when placed on the cornea. Suitably, the optical device has a thickness of between 2.0mm and 6.0mm, suitably between 2.0mm and 5.0mm, suitably between 2.1mm and 4.0mm.

The first and second surfaces may thus be spaced apart by between 2.0mm and 6.0mm, suitably between.2.0mm and 5.0mm, suitably between 2.1mm and 4.0mm. Suitably; the first and second surfaces are substantially equally spaced throughout the devices extent .

Where the first surface ±s^" arranged to^' conform to a distorted cornea and the second surface is spherical to replicate the undistorted cornea the separation between surfaces may vary but may remain within the defined limits .

Suitably, the optical device has a generally circular outline. Suitably, the optical device has a diameter slightly less than that of the cornea. Suitably, a diameter of 9-14mm, preferably 10mm. Suitably, the optical device comprises a substantially uniform material. Suitably, the optical device comprises a single material. For example, the optical device may comprise any one of HEMA, PMMA, Silicone, Silicone hydrogel , Hydrogel, Multiple Monomer Hydrogel, Multiphasic lenses, hydrophobic acrylic, hydrophilic acrylic. The optical device may preferably comprise plasma surfaced silicone to render it hydrophilic on the eye-contact surface .

Suitably, the optical device comprises a material having a high refractive index.

Suitably, the optical device comprises a material containing means of filtering out harmful radiation. For example to block violet or yellow or blue or UV-A or UV-B.

Suitably, the optical device comprises a truncated form. The device may thus be arranged to rest on a retracted lid and/or to give access to a surgical wound.

Suitably, the optical device is micro-trephinated. This may allow for the release σf air bubbles trapped between the optical device and the cornea in use.

Suitably, the optical device comprises a single¹/ use device. Suitably, the optical device comprises a sterile device. Alternatively, the optical device may comprise a sterilisable device which may be reusable.

Suitably, the optical device is arranged for use without., a holding ring. The device may however be used with a holding ring. The device may be arranged to_, be used with or without a contact gel such as a viscoelastic agent or carboxy-methylcellulose .

According to a second aspect of the present invention there is provided an optical device for use in eye surgery, said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed convex surface for providing an air interface, wherein said first and second surfaces have opposed focussing (optical) powers of" substantially equal magnitude .

Suitably, said device may comprise any feature as described in relation to the device of the first aspect.

According to a third aspect of the present invention there is provided an optical device for use in eye surgery said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed surface for providing an air interface.

Suitably, the second surface is convex.

The first surface may be arranged to mate with a deformed cornea and may be aspherical . The second surface,., may be spherical and may represent the undeformed cornea.

Suitably, the device according to the third aspect comprises an optical device for use in eye surgery to prevent fluid forming and/or pooling over a region of a cornea covered by the device in use, said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed surface for providing an air interface .

Suitably, said device is arranged for preventing fluid pooling over a region of the cornea^" covered by the device in use.

Suitably, said device may comprise any feature as described in relation to the device of the first aspect .

According to a fourth aspect of the present invention there is provided a method of preventing fluid lying and/or pooling over a region of a cornea, said method comprising applying an optical device to the eye such that a first surface of the device interfaces with the cornea and a second opposed surface of the device, lies above the level of fluid surrounding the device when the eye is orientated to point upwardly, such that said second surface provides an air interface.

Suitably, the method comprises preventing fluid ^"pooling over a region of a cornea.

Suitably, the method comprises locating the optical device in direct contact with the cornea, not at a spaced distance from the eye.

Suitably, the method employs a device according to the first and/or second and/or third aspect .

Suitably, the method is employed in combination with a method of surgery. The method of surgery suitably comprises observing the eye, suitably an anterior segment, through the device. Suitably, the device has substantially no focussing power, thus allowing a surgeon a clear view.

According to a fifth aspect of the present invention there is provided a method of observing an eye, said method comprising locating a device according to the first and/or second and/or third aspect adjacent the eye and viewing the eye through said device.

Suitably, the method comprises preventing fluid lying and/or pooling over a region of the cornea. Suitably, the method comprises preventing fluid pooling over a region of the cornea .

Suitably, the method comprises applying an optical device to the eye such that a first surface .of . the device interfaces with the cornea and a second opposed surface of the device lies above the level of fluid surrounding the device when the eye is orientated to point upwardly, such that said second surface provides an air interface .

The method may suitably comprise covering imperfect±ons- at a cornea surface and offering a more perfect and raised/lifted air interface for refraction. In this way imperfections of refraction caused by irregularity of the cornea surface and/or due to irrigating fluid flow or fluid pooling over the cornea may be reduced or eliminated.

Suitably, the method comprises observing the anterior segment of the eye. The method may comprise observing the iris and/or the eye's crystalline lens. The method may suitably not comprise observing the retina or other posterior structures of the eye.

Suitably, the method comprises using the optical device in combination with a magnifying viewing system, for example an operating microscope or operative telescopes.

The device may have no focussing power with air on either side of the device as the powers of the first and second surfaces may cancel one another out. However, when the first surface contacts the cornea the equal and opposite powers of first surface and anterior surface of the cornea may cancel one another out. Thus, the magnifying effect- of the second surface of the device may be only slightly reduced by the posterior surface of the cornea resulting in an overall magnifying effect. Suitably, this effect is similar to the effect of the front surface of the cornea in air, and suitably will not exceed +60 diopters and may for example be +50 diopters or less. The magnifying effect increases with the thickness of the device, which may make the device particularly suitable for use in dissections of the cornea, for example epikeratoplasty.

Suitably, the method employs a device according to the first and/or second and/or third aspect.

The method may suitably comprise any feature as described in relation to the fourth aspect .

According to a sixth aspect of the present invention there is provided a method of surgery comprising the use of an optical device according to the first and/or second and/or third aspect and/or the performance of a method according to the fourth and or fifth aspects.

Suitably, the method comprises a method of performing anterior segment eye surgery. The method may suitably not comprise performing vitreo retinal surgery.

According to a seventh aspect of the present invention there is provided a packaged product comprising a sterile packed optical device according to the first and/or second and/or third aspect .

BRIEF DESCRIPTION OF DRAWINGS

The present invention will now be illustrated by way of example with reference to the accompanying drawings in which:

Figure 1 is a cross-section showing fluid pooling over a corneal surface;

Figure 2 is a cross-section showing an optical device of the present invention in place; Figure 3 is a cross-section illustrating the shift of apparent depth when using the device of Figure 2 ;

Figure 4 is a cross-section illustrating a probe entering an eye and causing distortion thereof;

Figures 5A and 5B further illustrate distortion of the eye and cornea during surgery; and

Figure 6 is a cross-section showing an alternative embodiment of an optical device positioned on a deformed eye .

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

During eye operations in which the eye is orient,at.ed t;p point upwardly fluid may form over the eye .and. , can hinder surgery. One cause of this fluid formation can • be swelling of the^' conjunctiva causing irrigation fluid to pool over the eye. Figure 1 illustrates such a case. ^"'

As shown by Figure 1 an eye 1 has a cornea 2 having a corneal surface 2A and an anterior chamber 3. Surrounding the eye are ballooned conjunctiva 4. The conjunctival ballooning results in fluid 5 pooling in the cleft between the cornea 2 and the conjunctiva 4. This fluid pooling results in the loss of the normal refracting interface between air 6 and the corneal surface 2A over a significant part of the corneas extent. Under such circumstances surgery in the anterior chamber 5 of the eye 1 is difficult because of loss of surgical view resulting from the altered air-surface optics at locations 5A compared to those at 2A.

Figure 2 illustrates an optical device 10 in use. The device 10 comprises a transparent material and has a first concave surface 11 for interfacing with the surface 2A of the cornea 2 and an opposed convex surface 12 for providing an interface 12A with the air 6.

The optical device 10 comprises a transparent sterilisable material, e.g. silicone which is generally circular in outline and has a diameter slightly smaller than that of the cornea 2.

The optical device 10 has substantially no effective focussing (optical) power. The first and second surfaces 11, 12 each form a portion of a sphere and have radii similar to the radius of curvature of the cornea 2. The surfaces 11, 12 thus have a power of convergence of similar magnitude but opposite sign, i.e. one has converging power and the other diverging power. Thus, in use, when light passes from the eye structures through the optical device 10 to an observer (not shown) then the first surface 11 it passes through is concave and the second 12 convex. In the illustrated example these surfaces have near identical (but opposed) power of around 40 to 60 dioptres. Thus, in use, the observed relationship between structures and instruments may be maintained.

The device 10 comprises a single material which is sufficiently inexpensive to allow the device to be considered disposable. The material is non-abrasive and transmits sufficient light to permit visibility of normal microscopic anatomical structure and surgical manoeuvres within the eye.

The device has a thickness T of 3.0mm though in alternative embodiments this may vary and may for example be between 2.1 and 6.0mm, for example between 2.1 and 4.0mm. This thickness is sufficient to permit a new refracting air-surface interface 12A to be provided at a^' raised level above confounding fluids, such as surgical irrigation fluids 5 which form at the level of the original refracting air-corneal interface.

Accordingly, as can be seen in Figure 2, the pooling of fluid 5 is restricted to areas adjacent the conjunctiva 4 and prevented from covering a substantial part of the cornea 2. The optical device 10 raises the air interface 12A above the level of the fluid surface 5A allowing an observer, such as a surgeon, a clear view into the anterior chamber 3.

The device 10 is shown addressing the problem of fluid pooling but it may also be used to improve the clarity ,of view into the eye in a number of other circumstances-. . For example it may be used when the corneal .surface 2A is imperfect in shape, wetability, clarity- due to surface defect or when fluid flows over the cornea.

Figure 3 illustrates how the use of the optical device 10 shifts the apparent depth of structures and equipment within the eye 1 will shift a small amount forwards (upwards) towards the air interface 12A. As shown All is the apparent depth of the posterior capsule 7 without the device 10 in place and A12 is the apparent depth with the device 10 in place on the cornea 2.

The apparent depth is equal to the^' real depth divided by the refractive index of air to a medium. In practice the addition of the device 10 of thickness T, moves all forward to A12. This shift is only a fraction of the thickness e.g. for rigid silicon of refractive index 1.43 and T=3mm, the shift experience is approximately 0.9mm.

Structures and instruments within the eye will feel closer to the endothelium 8 than they actually are. However, the relationship between them will be substantially maintained. Thus, the optical device 10 may provide significant benefits in the clarity of view into the eye without creating hindering distorting effects that might be caused by a lens. - ^•

Although the device has no optical ^• power'/ in air,^" it^' may create a magnifying effect in use as the .first surface

(which is negative^"/minifying/divergent) of the device may be neutralised by the anterior surface of the cornea (which is positive/magnifying/convergent) when both are in contact . That may leave the magnifying effect of the second surface of the device only slightly reduced by the posterior surface of the cornea. This effect may assist with dissections of the cornea.

Figure 4 and Figures 5A and 5B illustrates the effect of inserting a surgical probe P into the eye. This causes the cornea to distort from the curvature shown as Rl to that shown as R2. Under these circumstances it is desirable for the first (posterior) surface of the device to have a shape which mates with the deformed cornea rather than the cornea in its natural form.

When a probe is passed through the cornea it causes simultaneous steepening in one meridian of the corneal surface and a corresponding flattening in the meridian at 90 degrees to the first. This can be predicted and an approximate shape fashioned on the first (posterior) surface of the device to better fit the anterior shape of the cornea and make the device more stable on the eye .

Figure 5A shows the cornea, from above, in an un-deformed condition. The vertical curvature, Rl, is approximately equal to the horizontal curvature. Figure 5B shows that when the eye wall is penetrated by a probe then .the curvatures in the cornea change, with e.g. vertical curvature steeper, R2 , and horizontal curvature flatter. However, under such distortion the cornea mean power remains the same . .,

As shown by Figure 6 an alternative embodiment of an optical device 110 more suitable for use with a deformed cornea comprises a first surface 111 having a form corresponding to the shape of the deformed cornea. The second surface 112 has a form corresponding to that of the first surface 111 and is equally spaced from it throughout the device. In an alternative embodiment (not illustrated) the second surface has a spherical .form substantially corresponding to that of the undeformed cornea . It will be appreciated that preferred embodiments of devices of the present invention may provide significant benefits in surgical procedures.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressϊy stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extends to any novel one, or any novel combination, of the' features disclosed in this specification (including . any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. An optical device for use in eye surgery, said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed surface for providing an air interface, wherein said device, in air, has substantially no focussing power.

2. A device according to claim 1, wherein said second surface comprises a convex surface and said first and second surfaces have opposed focussing (optical) powers of substantially equal mean magnitude.

3. An optical device for use in eye surgery, said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed convex surface for providing an air interface, wherein said first and second surfaces have opposed focussing (optical) powers of substantially equal magnitude .

4. An optical device for use in eye surgery said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed surface for providing an air interface.

5. An optical device for use in eye surgery to prevent fluid forming and/or pooling over a region of a cornea covered by the device in use, said device comprising a transparent material having a first concave surface for interfacing with a cornea and a second opposed surface for providing an air interface .

6. A device according to claim 4 or 5, wherein the second surface is convex.

7. A device according to any preceding claim, wherein the first surface is arranged to mate with a deformed cornea.

8. A device according to any preceding claim-, wherein the first and second surfaces each have a radius of curvature similar to that of a cornea of any eye with which the device is arranged to be used.

9. A device according any preceding claim, wherein said device can prevent fluid pooling over a region of a cornea covered by the device in use .

10,. A device according to any preceding claim, wherein the first and second surfaces ^■ have opposed focussing/refractive powers having mean magnitudes lying within,.5% of one another.

11. An optical device according to^' any preceding claim, wherein the optical device has a thickness of between 2.1mm and 6.0mm.

12. An optical device according to any preceding claim, wherein the optical device comprises a single material .

13. An optical device according to any preceding claim, wherein the optical device comprises a material having a high refractive index.

14. An optical device according to any preceding claim, wherein the optical device comprises a material containing means of filtering out harmful radiation.

15. An optical device according to any preceding, claim, wherein the optical device comprises a truncated form such that it can be arranged to rest on a retracted lid and/or to give access to a surgical wound.

16. An optical device according to any preceding claim, wherein the optical device is micro-trephinated such that it can allow for the release of air bubbles trapped between the optical device and the cornea in use.

17. An optical device according to any preceding claim, wherein the optical device comprises a single use device.

18. A method of preventing fluid lying and/or pooling over a region of a cornea, said method comprising applying an optical device to the eye such that a first surface of the device interfaces with the cornea and a second opposed surface of the device lies above the level of fluid surrounding the device when the eye is orientated to point upwardly, such that said second surface provides an air interface .

19. A method according to claim 18, wherein the method employs a device according to any of claims 1 to 17.

20. A method of observing an eye, said method comprising locating a device according to any of claims 1 to 17 adjacent the eye and viewing the eye through said device .

21. A method according to claim 20, wherein the method comprises a method according to claim 18.

22. A method of surgery comprising the use of an optical device according to any of claims 1 to 17 and/or the performance of a method according to any of claims 18 to 21.

23. A packaged product comprising a sterile packed optical device according to any of claims 1 to 17.