WO2017051185A1

WO2017051185A1 - Contact lens

Info

Publication number: WO2017051185A1
Application number: PCT/GB2016/052965
Authority: WO
Inventors: Brian David Cantor
Original assignee: Brian David Cantor
Priority date: 2015-09-25
Filing date: 2016-09-23
Publication date: 2017-03-30
Also published as: GB2542608A; GB201517011D0

Abstract

A contact lens is provided which affords wearers some alleviation to age-related macular degeneration (ARMD). In essence, the contact lens possesses some inherent prismatic deflective capability. Most simply, the contact lens is formed in a manner so as to define one or more prismatically active surfaces within its structure, such that when in place on the eye of a wearer, said prismatically active surfaces act to deflect light incident thereon away from a central region of the macula of said eye. In different embodiments, the contact lens may have embedded one or more prismatically active structures which themselves possess one or more prismatically active surfaces which produce the desired light deflecting effect.

Description

CONTACT LENS

Field of the Invention The present invention relates to a contact lens, and more specifically to a contact lens adapted for corrective treatment of eye conditions other than common long- and shortsightedness (hypermetropia and myopia respectively).

Background to the Invention

Contact lenses have been in widespread use since at least the 1970s, and are well known in the corrective treatment of various eye conditions, most commonly hypermetropia and myopia. Corrective contact lenses are designed to improve vision, most commonly by correcting refractive error, and most commonly achieve this by having positive- or negative-meniscus lens shapes (where the radius of curvature of the inner surface is respectively less or greater than that of the outer surface). The lenses are designed so that light passing through them enters the eye with the proper power for clear vision.

A spherical contact lens bends light evenly in every direction (horizontally, vertically, etc.) - and as such are typically used to correct eye conditions resulting from an inherent weakening or strengthening of the integral lens within the human eye (myopia and hypermetropia). By contrast, a toric contact lens has a different focusing power horizontally than it does vertically (or vice versa), and as a result can correct, to a certain extent, the well known condition of astigmatism, which can result from a non-uniform deformation of the eye such that the radius of curvature in the horizontal or x-axis direction is different from that in the vertical or y-axis direction. The skilled reader will therefore immediately understand that the orientation of a toric contact lens on the wearer's eye is critical as respective x- and y- axes of eye and lens must be more or less aligned if the lens is to correct the deficiency. Accordingly, a toric contact lens possesses additional design characteristics which prevent the lens from rotating away from the ideal alignment. This can be done by weighting the bottom of the lens or by using other physical characteristics to rotate the lens back into position. Some toric contact lenses have marks or etchings that can assist the eye doctor in fitting the lens. The first disposable toric lenses were introduced in 2000 by Vistakon. One other well known human eye condition is that of presbyopia, correction of which necessitates a need for a two different optical corrective prescriptions, one for reading and other close-up activities typically dextrous in nature, and one for bringing distant objects into sharper focus. As far as contact lenses are concerned, two main types exist for presbyopia: multifocal contact lenses and contact lenses for "Monovision".

Multifocal contact lenses (for example bifocal or progressive contact lenses) are comparable to spectacles with bifocals or progressive lenses because they have multiple focal points. Common multifocal lenses generally possess a central circular region in the middle of the lens having a first optical magnification, and then one or more

progressively optically weaker or stronger annular regions surrounding the central region. Multifocal contact lenses are typically designed for constant viewing through the center of the lens, but some designs do incorporate a shift in lens position to view through the reading power (similar to bifocal glasses).

Monovision is the use of single vision lenses (one focal point per lens) to focus one eye for distance vision (typically the person's dominant eye) and the other eye for near work. The brain then learns to use this setup to see clearly at all distances. A technique called modified monovision uses multifocal lenses and also specializes one eye for distance and one eye for near, thus gaining the benefits of both systems.

Contact lenses can also be employed to correct optical deficiencies which are purely chromatic (e.g. colour-blindness), and more recent studies have even suggested that contact lenses might be used in the treatment of dyslexia. Most recently, research is being conducted into the use of contact lenses to provide image magnification, and indeed it has already been proposed to provide contact lenses with telescopic elements embedded therein. US90633352 for example describes such a telescopic contact lens.

Despite the above advances in contact lenses, the human eye condition of age-related macular degeneration (ARMD) has, up until now, not readily been adequately or even partially corrected by an appropriately designed contact lens. This is because ARMD involves a degeneration and attendant deterioration of the macula of the human eye, which at this time cannot be repaired by surgery or medication. ARMD is a form of "central geographic atrophy", and results from atrophy of the retinal pigment epithelial layer below the retina. This causes vision loss through loss of photoreceptors (rods and cones) in the central part of the eye - in short, a form of blindness.

Although the atrophied eye tissue cannot be repaired or treated, there is a (now widespread) surgical treatment for ARMD - that of intraocular lens (IOL) insertions or implants. Indeed, IOL implants can also be used to treat the common cataract or myopia. The most common type of IOL is the pseudophakic IOL. These are implanted during cataract surgery, after the cloudy crystalline cataract lens has been removed. The pseudophakic IOL replaces the original crystalline lens, and provides the light focusing function originally undertaken by the crystalline lens. The second type of IOL, more commonly known as a phakic intraocular lens (PIOL), is a lens which is placed over the existing natural lens, and is used in refractive surgery to change the eye's optical power as a treatment for myopia. lOLs usually consist of a small plastic lens with plastic side struts, called haptics, to hold the lens in place within the capsular bag inside the eye. lOLs were traditionally made of an inflexible material (PMMA), although this has largely been superseded by the use of flexible materials. Most lOLs fitted today are fixed monofocal lenses matched to distance vision. However, other types are available, such as multifocal lOLs which provide the patient with multiple-focused vision at far and reading distance, and adaptive lOLs which provide the patient with limited visual accommodation. In order to treat ARMD, the IOL implant is a lens which effectively deflects light passing through the lens away from the eye's focal axis by a small amount so that light falls onto an area of the retina which has not been affected by ARMD.

It is an object of this invention to provide a contact lens adapted to at least mitigate, if not entirely overcome the affects of ARMD.

Summary of the Invention

According to the present invention there is provided a contact lens which includes one or more prismatically active surfaces, such that when in place on the eye of a wearer, said prismatically active surfaces act to deflect light incident thereon away from the macula of said eye, or a central region thereof. Preferably, the one or more prismatically active surfaces act in combination with one or more of:

One or more non-prismatically active surfaces of said contact lens,

- A surface of the eye, and

- The meniscal surface of intervening ocular fluid, such as tear liquid, and/or the surface of such liquid which interfaces with the cornea,

to deflect light in the required manner.

Preferably, the one or more prismatically active surfaces of said contact lens are discreet and distinguishable from the conventional exterior and/or interior surfaces of said contact lens, while also preferably forming an integral part thereof. In the context of this application, the exterior surface of a contact lens should be understood as being that surface which is outwardly disposed relative to the eye when in place, and which thus provides the primary interface with the ambient atmosphere, whereas the interior surface is that surface which contacts the wearer's cornea, or more accurately, an ocular/tear fluid layer covering it, and is thus the primary interface with the wearer's eye.

In one preferred embodiment, the one or more prismatically active surfaces are provided on one or more prismatically active structures which may be either partially or totally embedded within the structure of the contact lens, that is, completely or partially embedded between the exterior and interior surfaces thereof. In such cases, the one or more prismatically active surfaces may be entirely unconnected to and separate from the interior and exterior surfaces of the contact lens, and further preferably disposed therebetween.

In a yet further preferred embodiment, the one or more prismatically active surfaces are provided on one or more prismatically active structures which are surface mounted to one or more of the exterior and interior surfaces of the contact lens. Most preferably, the one or more prismatically active structures are substantially laminar and adhered, fused, or otherwise affixed to one or both of the exterior and interior surfaces of the contact lens. Most preferably, a single prismatically active structure is adhered to the interior surface of the contact lens. In embodiments, the contact lens may be one or more of:

a rigid gas permeable (RCP) lens,

a hard or soft contact lens, or some combination thereof,

made of a plastics, polycarbonate, hydrophilic material, and/or hybrid material - pressed, formed, moulded milled or otherwise cut on a lathe,

- toric in that it possesses some specific feature which ensures that a desired

angular orientation of the lens relative to the eye is generally maintained and/or stabilised. In a preferred embodiment, the contact lens and the one or more prismatically active structures may be provided together in the form of a piggyback contact lens. +

In a further preferred embodiment, the contact lens may be a hybrid lens comprising both hard and soft material regions, and the one or more prismatically active surfaces may be defined at or by the one or more interfaces between said hard and soft materials.

Most preferably, the prismatically active surfaces are machined into a contact lens, or impressed therein by means of plastic deformation of the lens material.

Thus, contact lenses as prescribed above can be used to provide correction for ARMD, which directly affects the macula, being that portion of the retina on which focused light from the outside world is incident, and which commonly degenerates in the elderly producing blind spots. Contact lenses having with one or prismatically active surfaces (or structures possessing such) effectively deflect or divert light passing through their clear translucent bodies such that it falls not on an atrophied macular (usually central) region, but on some other optically receptive region of the macula or retina, radially displaced from the atrophied region by a small amount. In certain cases, where a directly central region of the macula has atrophied, it is not necessary to provide a toric, orientationally stabilised contact lens because a spherical annular area of optically receptive functioning tissue will completely surround the damaged macular region, and it is not therefore necessary to deflect light to a specific region which is unaffected by ARMD - light can fall on any area within that annular region, and an ARMD sufferer will still receive a useful and complete image.

Alternatively, however, if ARMD is widespread such that only a specific area of optically sensitive, macular or retinal tissue remains, then a toric contact lens with orientational stability on the eye surface is desirable, as such a lens, provided with prismatically active surfaces or structures, would be capable of consistently deflecting light onto a specific macular or retinal portion of optically sensitive tissue within the eye - in this manner, the present invention offers correction for even relatively acute ARMD conditions.

A specific embodiment of the invention is now described by way of example and with reference to the accompanying drawings wherein.

Brief Description of the Drawings

Figures 1 & 2 show sectional views of example contact lenses according to the present invention, and

Figures 3 & 4 shows show further contact lenses in accordance with the invention.

Detailed Description

Referring firstly to Figure 1, there is shown a sectional view through a contact lens indicated generally at 2 and having exterior and interior surfaces 4, 6 respectively. The interior surface 6 has a continuous arcuate shape, whereas although the exterior surface 4 is of predominantly corresponding arcuate shape, there is a discontinuity at 4X, at which the axial thickness of the lens abruptly reduces, said discontinuity effectively defining upper and lower halves 4A, 4B of the lens which although being of essentially identical thicknesses at their free ends extremities 4A-1, 4B-1, are of different thicknesses where they meet at said discontinuity. In the contact of this invention, the prismatically active surface may be considered to be any one of the exterior surfaces of the upper and lower halves 4A, 4B, or the ledge-like surface 4X. Of course, when the lens 2 is in place on the cornea of a wearer, tear fluid may naturally occlude or settle in, and/or fill the reduced thickness region of the lower half of the lens 2, and shown by the hatched area 8 (of course, the entire exterior surface of the lens may be continually covered by a layer of tear fluid - the illustration merely conveys that area 8 would be additional, and may therefore serve to provide some prismatic effect). The exterior and interior (interfacing with the lens exterior surface) may be considered as providing some prismatically active function, brought about by the discontinuous or two-part arcuate shape of the exterior surface of the lens.

In Figure 2, a further contact lens 10 is shown, again having exterior and interior surfaces 12, 14. The exterior surface 12 is provided with two discontinuities 12A 12B at which points, the thickness of the lens abruptly reduces giving rise to a 2 ledge-like formations or steps. Said ledge-like formations may be radially symmetrically disposed of the central focal axis of the lens, or they may be asymmetrically disposed thereof, or both formations may lie to one or other side of the focal axis of the lens. In any event, the prismatically active surfaces may be considered to be either the ledge-like formations 12A, 12B themselves, or the portion of the exterior surface of the lens defined between them. Again, as for Figure 1 , any natural occlusion of the reduced thickness regions of the contact lens with tear fluid, which may be retained in place by surface tension effects, may also be considered as providing one or more prismatically active surfaces, in the context hereof. Depending on the material from which the lenses of Figs. 1 & 2 are manufactured, they may be simply pressed or formed, or they may be machined.

Referring to Figure 3, a further embodiment is shown in which a contact lens 20 having exterior and interior surfaces 22, 24 is shown having a discrete translucent shim 26 fused, adhered or otherwise affixed to the exterior surface 22 of said lens. In this case, the shim provides the prismatically active surfaces by means of which light is deflected away from the conventional, symmetric focal axis of the lens. Also in the figure, dotted line 28 demonstrates that alternately, or additionally, a similar shim may be provided on the interior surface 24. The shim may be axially symmetrically disposed, or it may be offset from such a position, depending on requirements. Furthermore, the thickness of the shim may vary with radial distance from said focal axis, although most preferably the thickness of the shim at any radial distance from said focal axis will be uniform for any azimuth angle subtended therewith. The shape of the shim, when viewed in front elevation, may be circular or elliptic, but other shapes are of course possible. In Figure 4, there is shown a yet further embodiment of a contact lens 30 having exterior and interior surfaces 32, 34, and within the body of which is embedded a shim insert 36, either or both of the exterior and embedded interior surfaces of which are prismatically active in that they serve to deflect light passing through them in the manner required. Again, as for figure 3, the shim insert 36 may be fused, adhered or otherwise affixed to the contact lens preferably in a suitably and precisely shaped depression provided in the exterior surface of the contact lens so that the shim insert exterior surface lies flush with the exterior surface of the contact lens 32, as shown. Similarly to Fig. 3, another shim insert 38 may additionally or alternately be provided in the interior surface of the contact lens, and again, as for the Fig. 3 embodiment:

axial positioning of the shim inserts may be symmetric or asymmetric,

- their shapes may be circular, elliptic, or some other desired shape (possibly being symmetrical about the vertical or horizontal, when the contact lens is viewed in front elevation as it would be positioned on the sys of a wearer), and

- their thicknesses may vary, preferably radially, and most preferably additionally or alternately with distance along one of the horizontal or vertical axes abovementioned such that the shim insert is thickest at one edge and thinnest at another edge diametrically (if circular) opposite that one egde.

Claims

1. According to the present invention there is provided a contact lens which includes one or more prismatically active surfaces, such that when in place on the eye of a wearer, said prismatically active surfaces act to deflect light incident thereon away from a central region of the macula of said eye, wherein the one or more prismatically active surfaces of the contact lens are discrete and distinguishable from the continuously arcuate exterior or interior surface of said contact lens in which they are provided.

2. A contact lens according to claim 1 wherein the one or more prismatically active surfaces act in combination with one or more of:

one or more non-prismatically active surfaces of said contact lens,

a surface of the eye, and

a meniscal surface of intervening ocular fluid, such as tear liquid, and/or the surface of such liquid which interfaces with the cornea,

to deflect light in the required manner.

3. A contact lens according to either preceding claim wherein the one or more prismatically active surfaces form an integral part of the arcuate exterior or interior surface of the contact lens.

4. A contact lens according to any preceding claim wherein the one or more prismatically active surfaces are provided by one or more prismatically active structures having at least one prismatically active surface and which are at least partially embedded within the structure of the contact lens.

5. A contact lens according to claim 4 wherein the one or more prismatically active surfaces are formed exclusively on the one or more prismatically active structures.

6. A contact lens according to any of claims 1 -4 wherein the one or more prismatically active surfaces are provided on one or more prismatically active structures which are surface mounted to one or more of the exterior and interior surfaces of the contact lens.

7. A contact lens according to claim 6 wherein the one or more prismatically active structures are substantially laminar and one of: adhered and fused to the exterior or interior surface of the contact lens.

8. A contact lens according to 6 or 7 wherein a single prismatically active structure is adhered to the interior surface of the contact lens.

9. A contact lens according to any of claims 5-9 wherein one or more prismatically active structures and the contact lens together form a piggyback contact lens.

10. A contact lens according to any of claims 4-8 wherein one or more prismatically active structures and the contact lens are formed of one of: a hard material and a soft material, so as to create a hybrid contact lens.

1 1. A contact lens according to any preceding claim wherein the contact lens is one or more of:

a rigid gas permeable (RCP) lens,

a hard or soft contact lens, or some combination thereof,

- toric in that it possesses some specific feature which ensures that a desired angular orientation of the lens relative to the eye is generally maintained and/or stabilised.