US 20080125862 A1
An intraocular lens device including a foldable lens optic configured to fit through a small incision in the eye connected to a lens frame haptic configured to fit separately through a small incision in the eye.
46. An intraocular lens device for use in an eye, said intraocular lens device comprising:
a foldable lens optic configured to fit through a small incision in the eye;
a lens frame haptic configured to fit through a small incision in the eye, lens frame haptic connectable to said foldable lens optic, said lens frame haptic stretching said foldable lens optic under tension during assembly of said intraocular lens device, and then maintaining said foldable lens optic in an operational configuration in the eye.
47. An intraocular lens device for use in an eye, said intraocular lens device comprising:
a foldable lens optic configured to fit through a small incision in the eye, said lens optic including at least one eyelet;
a lens frame haptic configured to fit through a small incision in the eye, said lens frame haptic including at least one cleat cooperating with said eyelet of said lens optic for connecting said foldable lens optic to said lens frame haptic, said cleat placing said eyelet under tension while connecting said eyelet to said at least one cleat to anchor said lens optic to said lens frame haptic.
48. An intraocular lens device for use in an eye, said intraocular lens device comprising:
a foldable lens optic configured to fit through a small incision in the eye, said lens optic including at least one stretchable eyelet;
a lens frame haptic configured to fit through a small incision in the eye, said lens frame haptic including at least one cleat cooperating with said stretchable eyelet of said lens optic for connecting said foldable lens optic to said lens frame haptic, said lens frame haptic operating through said cleat for connecting and stretching said stretchable eyelet of said lens optic and placing said foldable lens optic under tension during assembly for securely connecting anchoring and maintaining said lens optic on said lens frame haptic during operation in the eye.
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The present invention generally relates to a two part “L”-shaped IOL. More specifically, the present invention relates to an IOL film frame which is insertable through an opening as small as 1.0 mm without deforming the frame and a lens which can then be attached within the eye.
The history of intraocular lenses (IOLs) is a long and varied one. Intraocular lenses can be used to treat a wide diversity of eye conditions ranging from cataracts to any type of eyesight correction. In addition, IOLs can be used to replace an irreversibly damaged lens in the eye—aphakic eyes. Alternatively, the lenses can be used in addition to the natural lens to correct the vision—phakic eyes. These lenses can be placed in the anterior or posterior chambers of the eye.
Early IOL researchers were plagued with problems associated with the materials which were obtainable to them at the time (early 1950's) making the lenses too heavy and too large. Surgery of the eye was in its infancy and therefore there were many problems with the surgical procedures. Since that time the quality, size and weight of the optics as well as microsurgical procedures have dramatically improved.
The earliest IOL's were placed in the anterior chamber of the eye, this being the easiest chamber to get to. Along with the early problems with the optics and surgical techniques, placement of a lens in the anterior chamber proved difficult because the anterior chamber is narrow (about 1.5 to 2.5 mm).
The second location is the angle between the cornea and the iris. Angle supported anterior chamber IOLs took advantage of the anterior chamber angle to support and fix the IOL in place. By angling the IOL into opposite sides of the anterior chamber, the natural angle was used to keep the IOL from moving. However, early lenses experienced marked problems with endothelial loss due to chafing against the early thick lenses. Later lenses were able to reduce the significance of this problem, but still retained problems associated with placement of the IOL in the chamber angle. The biological properties of that angle make it a very sensitive area. The structures associated with equalizing the internal pressure of the eye are located in that area. Additionally, the tissue in the area is easily irritated and irritation initiates a growth of fibrous tissue, called synechiae. The IOL fixation must be gentle in order to reduce irritation, but stable enough that it will not be easily moveable. This compromise is difficult to obtain. In addition, although the results were excellent in the short-term, there was a significant problem in the long term with altered night vision, loss of endothelial cell populations and alteration of the anterior uvea. These problems as well as the fact that such anteriorly positioned lenses were uncomfortable to the patient, caused many doctors to abandon anterior chamber IOL's.
A third location was developed later and involves implanting a contact lens between the iris and the natural lens. These lenses are called ICL's or implantable contact lenses. However, the ICL's are suspected of initiating cataracts and glaucoma.
As the development of the IOL's became more sophisticated, Ophthalmologists recognized various problems. A typical IOL is composed of an optic, the ‘lens’ part of the structure, and a mounting mechanism called a haptic. The haptics are the part of the IOL that comes in contact with the eye tissue to hold the lens optic in place. There were essentially two major types of haptics which were developed—fiber and plate haptics. Fiber haptics are slender strands of resilient material which are attached at one end to the optic, and which rest, at their other end, against the eye. Fiber haptics have the advantage of being very light and slender. This would seem to make them ideal by causing less damage to the tissue and additionally being aesthetically pleasing because they are very narrow. The slenderness makes it more difficult for someone looking at the patient to see the IOL through the eye. Plate haptics are machined or molded from stock materials and have a central optic and an outer perimeter which rests against the eye. Because of their size, plate haptics tend to be more easily seen from outside in the patient's eye and the addition of extra material weight to the IOL and reduced flexibility as compared to fiber haptics leads to poor fixation and consequent migration or dislocation of the IOL. While, fiber haptics have the disadvantage of initiating a process in which the body builds fibrous tissue or synechiae around the fiber haptic which immobilizes the iris, the larger plate haptic very rarely, if ever, causes such a reaction.
The adverse problems associated with the earlier anterior chamber haptic designs encouraged the development of IOL's for the posterior chamber for the majority of implants.
The surgical process may or may not include removal of the diseased natural lens using a process called phakoemulsification. The more standardized procedure for lens implantation involves removal of a diseased natural lens followed by implantation of an artificial lens. Phakoemulsification of the diseased lens is accomplished through about a 2 to 4 mm (small) incision in the eye and through a capsulorhexis incision in the capsule that encloses the lens in the posterior chamber, then an artificial intraocular lens implant is implanted back through the capsulorhexus into the capsular bag. For other types of procedures, the natural lens may not require removal at all.
As surgical procedures have developed, there is a trend toward reducing the size of the incision in the eye. Although a 3 mm incision does not usually require sutures for healing, it increases the chances of infection, heals slower, and may provide for a slower operation then if an incision of less than 3 mm is used. However, presently IOLs cannot be inserted into a very small incision, as small as 1 mm.
Accordingly, an intraocular lens (IOL) has been developed. The intraocular lens features an optic and a haptic. The haptic is “V”-shaped and features relatively more rigid elements formed of relatively higher modulus (harder) materials which are flexibly springy when thin. The haptics may also comprise less rigid elements formed of relatively lower modulus (softer) materials bridging a discontinuity separating the haptics. The “V”-shaped haptic allows for insertion of the haptic through an opening in the eye as small as about 1 mm without deforming the frame. The haptic also features a fastening structure for the separate optic, preferably a cleat. The foldable optic is then inserted into the eye through the same ultra small incision and attached to the haptic, preferably the haptic cleat, by way of a formed aperture or eyelet in the optic.
The higher modulus springy polymeric material may be selected from polyimide, polyetheretherketone, polycarbonate, polymethylpentene, polymethylmethyl methacrylate, polypropylene, polyvinylidene fluoride, polysulfone, and polyether sulfone. Preferably, the higher modulus material is polyphenylsulfone (PPSU). Preferably, the higher modulus material has a modulus of elasticity of about 100,000 to about 500,000 psi, even more preferably about 340,000 psi and has a hardness of about 60 to 95 on the shore D scale, but more specifically a Rockwell R hardness of 120 to 130. The lower modulus rubbery material may be an elastomer selected from silicones, urethane, or hydrophilic acrylics. Preferably, the lower modulus elastomeric material has a modulus of about 100 to about 1000 psi (unit load at 300% elongation). Preferably, lower modulus material has a hardness of about 15 to 70 on the shore A scale of hardness. Preferably, the lower modulus material is a dispersion such as NUSIL MED 6605, 6400, 6820, 6604, and 6607, or the like.
In one embodiment, the relatively more rigid elements comprises a “V”-shaped frame. The frame forms three haptics which may be formed from a single uniform piece of material. The haptic may contain a cleat for attachment of the lens. The haptic may additionally contain a slot open on one side to form a hinge which is bendable at the slot. The haptic may alternatively contain a groove to form a hinge which is bendable at the groove.
The lower modulus material may partially or completely cover the haptics. In one embodiment, the lower modulus material is extended beyond the tip of the haptic to produce a softer contact point for the eye tissue. The lower modulus material may be applied by first surface treating the higher modulus material and then molding the lower modulus material onto the treated surface. Preferably, the surface treatment is a corona or plasma treatment and additionally a primer. Preferably, the molding is dip molding, cast molding, or injection molding. Primers such as Nusil Med may also be used singly or in combination.
The invention is a “V”-shaped intraocular lens frame, having multiple plate haptic elements preferably formed of relatively higher modulus harder material and containing an attachment for a separate optic.
The invention may optionally have a hinge connecting the toe region to the foot region, the hinge being formed of relatively lower modulus material. This can be referred to as a “duplex” material.
The optic may be any type of lens. Preferably, the optic is a refractive lens, or an interference lens, producing a thin optic. The optic could be toric, aspheric, multi-element, positive or negative.
Further, the invention is an intraocular lens having an optic; and a haptic including stiffer elements joined by flexible elements of different materials.
Still further, the invention is a method for making an intraocular lens haptic, having the steps of forming a frame, coating a location of the frame, and breaking the frame at the location.
Still further, the invention is a method of mounting a lens in the anterior chamber of an eye, having the steps of supporting a lens on a plate haptic at the angle of the anterior chamber; and bending the haptic at a preferential hinge line to reduce pressure against the angle.
Accordingly, a haptic in the form of a “V”-shape has been developed for a two part IOL. This thin film frame haptic is insertable through an opening in the eye as small as about 1 mm without deformation of the haptic. This film frame haptic is also lightweight, springy and non-irritating, low cost, surgically implantable with a minimum of trauma to the eye, aesthetically pleasing, and does not support fibrous tissue growth. This IOL works in the anterior or posterior chamber of the eye for phakic or aphakic lenses. This haptic additionally comprises a fastener for a separate optic.
This “V”-shaped IOL film frame is a haptic system based on a high modulus, shaped skeletal frame or plate haptic. The haptic system may optionally be assembled with low modulus, soft, elastomeric hinged zones. The more rigid frame or haptic in combination with the soft hinges ensures that the lens and haptic assembly will maintain its shape and stay ideally situated in the anterior chamber angle of the eye or in the posterior chamber. Whereas, a haptic of a single soft material will not maintain a desirable shape and will be more noodle-like in its spirit, the compliant hinge can automatically adjust to the normal movements of an eye.
The more standardized procedure for the removal of a diseased natural lens 30 followed by implantation of an artificial lens involves the phakoemulsification of the diseased lens through a small incision in the eye and through a capsulorllexis incision in the capsule that encloses the lens in the posterior chamber 18, then an artificial intraocular lens implant is implanted back through the capsulorhexus into the capsular bag. For other types of procedures, the natural lens 30 may not require removal at all. The optic 200 of the IOL 10 used in these procedures includes a separate centrally located optical zone and may be configured for implantation into either the anterior 16 or posterior chamber 18 and may be used for either procedure set out above. The haptic 110 of the IOL 10 extends radially outwardly in the general plane of the optic 200.
With reference now to
In a preferred embodiment, each foot 121 may have a hinge region 120 which can be configured in a number of ways, but has the property of being more elastic than the main body of the foot 121. This hinge region 120 is formed of a material which is more elastic than the remainder of the lens frame haptic 110. In the preferred embodiment, the hinge region 120 is covered in an elastomeric material 127 which extends between the foot 121 and toe 150. The hinge zone 120 can be a thinner section in the frame, or a discontinuous opening in the frame where the elastomer 127 extends between the foot zone 121 and the toe portion 150. The hinge 120 and toe 150 can be produced in a variety of ways which are described in detail in application Ser. No. 09/______, filed May 12, 2000.
With further reference to
The lens optic 200 can be attached to the frame haptic 110 in a variety of ways. A preferred embodiment is shown in
With reference to
The cleats 300 of the invention have been shown to work particularly well for the intended purpose. Therefore it is envisioned that they could be used to attach any type of IOL before insertion or after insertion. In addition, they would allow the surgeon a choice of lenses or powers to insert and the surgeon could potentially clip one or more lenses onto the cleat 300. A further aid to the surgeon would be to tint the cleats 300 and/or eyelets 400 such that they would be more visually identifiable to the surgeon during the operation.
With reference to
After photo-cutting, the arcuate vaulting curves and shapes are secondarily formed into the haptic by mounting the frame on a dihedral shaped tool or equivalent and baked in an oven between 150° F. up to 550° F. depending on the haptic machine requirements.
The film frame haptic 110 is typically next polished to remove any rough edges. The preferred method of polishing involves abrasive tumble agitation polishing with glass beads. An alternative method for polishing the film frame haptic 110 and feet 121 includes flame polishing. At least the areas of the film frame or haptic 110 away from the optic region, which are to be hinges, are then treated such that an elastomeric compound can be attached. An alternative surface treatment includes plasma (a low pressure corona treatment) treating. Alternatively, the entire frame 110 could be surface treated or primed. Additionally, surface roughening such as by grit or vapor blasting can be included.
In the preferred embodiment, the frame haptic 110 is polyphenylsulfone which has a tensile modulus of about 340,000 psi (using test method D 638 of the ASTM) and is clear but exhibits a natural UV light absorbence property below 400 nm's resulting in a yellowish or amber tint. The frame haptic 110 is preferably made from film which is generally ≦0.025 cm (0.010 inches) thick, preferably 0.001 to 0.005 inches thick, but could be as thick as 0.012 inches or even as thin as 0.0005 inches. In the preferred embodiment the feet 121 are identical, but, non-identical feet 121 configurations can be paired for use in an alternative embodiment when necessary. The thinness of the film frame haptic 110 contributes to its springiness and lightness which is advantageous in that the IOL is less likely to be disrupted from its initial position.
The film lenses of these designs are typically about half the weight of a standard lens and can be between 2 to 10 milligrams and as low as 1 milligram in weight in air and about 10% of this when in the aqueous of the eye. Preferably the lens is flexible but may be made of a hard, stiff, low memory material. However, in the preferred embodiment, the lens is made of silicone and the chosen silicone can be as low as 15 shore A. The index (N) value would be 1.430 to 1.460.
After the haptic 110 is inserted into the very small opening and positioned in the eye as desired (see
With reference to
With continued reference to
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After coating, the hinge regions 120 may be produced by breaking the high modulus material at the hinges 120, scores, or notches. This may be done by flexing the region until the high modulus material work hardens and breaks. Alternatively, the hinge region may not need to be broken. The dimensions included in
Alternative embodiments of the invention are shown in
In most previous IOL's, the lenses have predominantly been round. However, it can be envisioned that the lens can be of many shapes. For example, in
A 2 mm incision is made near the limbus of the eye. Buffers are injected into the anterior chamber. The frame is inserted as shown in
Therefore, the IOL of the present invention presents a number of advantages. It is inserted in two separate pieces significantly reducing the bulk so that the incision can be as narrow as 1 mm. It is lightweight and thin which reduces corneal chafing and pupilary block. In addition, because of the hinges and toes and arcuate shape, it is capable of being inserted and resting on the anterior chamber angle with a minimum of damage to the tissues as well as a minimum of discomfort to the patient. The fact that it is a plate haptic shape eliminates the problem of synechiae, and it can be used in a phakic or aphakic eye.
One advantage of the present invention is that because the lens is a multi-part assembly, the ideal properties of each part of the IOL can be retained. For example, the haptic is ideally more rigidly springy and can be constructed to fit into a very narrow incision without deformation. The lens, although it is between 4 mm and 7 mm, can be inserted into a narrow incision because it is constructed of a more pliable and soft material and can be folded, squeezed or rolled, more than it could be with the attached haptic, to be inserted into a considerably smaller incision. Therefore a multi-part IOL allows for insertion into a much narrower incision, than an assembled lens.
The lens can be implanted into the eye using a variety of surgical implant techniques known in the art. Although the preferred embodiment is that the lens be implanted into the anterior chamber, using the anterior chamber angles, it can be envisioned that the lens could also be implanted in the posterior chamber.
Additionally, any combination of the materials used will result in a lens that can be sterilized by a variety of standard methods such as ethylene oxide (ETO) or steam autoclaving at 250° F. or any other acceptable method and the lens will show long term biocompatablity and hydrolytic stability.
While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims: