Intraocular lens

An intraocular lens which may be surgically implanted into the human eye. The lens has two sinuous support strands located at diametrically opposite sides thereof. The support strands allow the lens to be placed either in the ciliary sulcus or the capsular bag.

BACKGROUND OF THE INVENTION 
In opthalmic surgery, following removal of the lens of the eye, an 
intraocular lens is implanted to take the place of the lens removed. 
Various type of such lenses have been proposed and are in use. Lenses 
designed to be placed in the posterior chamber may be implanted in either 
the ciliary sulcus or the capsular bag of the eye. For example, U.S. Pat. 
No. 4,159,546 discloses an intraocular lens supported by a plurality of 
flexible strands secured to the lens body. The strands permit the lens to 
be supported in the posterior chamber of the eye. Numerous other lens 
designs are shown in the The Intraocular Implant Lens Development and 
Results, published by the Williams and Wilkens Company, Baltimore, Md., 
1975, pages 16-23. 
Although great advances have been made over the years in intraocular 
lenses, the prior art designs are not without their problems. The very 
common "J-looped" lenses (see FIG. 1B) are made in varying sizes depending 
upon whether they are meant to be placed in the capsular bag or the 
ciliary sulcus. The J-loops are not very compressible, and therefore if a 
large lens is placed within the capsular bag, it is a difficult fit. On 
the other hand, a small lens which is meant to go into the capsular bag 
may "rattle about" and irritate intraocular structures and get out of 
position if placed in the ciliary sulcus. It is often particularly 
difficult for the surgeon to be sure that a lens which is meant to be 
placed in the capsular bag is indeed in the bag, or that one which is 
placed in the sulcus is indeed solely in the sulcus and not in the bag. 
Sometimes, one loop is placed in the bag and the second loop in the sulcus 
in spite of the surgeon's best efforts. 
Another problem with "J-looped" lenses is their poor compressibility, which 
makes them difficult to insert, since once in place in the anterior 
chamber, they must be rotated, or "dialed" into proper position in the 
posterior chamber. This requires the surgeon to make two separate 
movements to properly place the lens. 
Other prior art lenses (see FIG. 1A) have very long gently curving loops 
which exert gentle pressure and are easily compressible, but, because of 
the extreme length of the loop, the lens is much more difficult to 
implant. This type of lens requires intraocular manipulation to place it 
into position in the posterior chamber behind the iris after the lens has 
been placed preliminarily in the anterior chamber. Thereafter, the lens 
must be pushed into the eye from anterior to posterior chamber. This 
increased intraocular manipulation increases the risk of injury to the 
eye. 
The present invention avoids these problems by allowing each lens support 
strand to be compressed radially for a considerable distance without 
significantly increasing the reaction force exerted outward toward the 
lens optic. An advantage of this design is that the lens will push outward 
with about the same force regardless of whether the loop is compressed 
mildly if it lies in the ciliary sulcus or compressed more strongly if it 
lies within the capsular bag. 
The lens support strands of the present invention have flat or straight 
ends. This offers the advantage of allowing the surgeon to more readily 
place the lens without the need for rotating or "dialing" the lens into 
place. 
Another advantage of this design is that the diameter of the lens becomes 
less critical. It is no longer necessary to use a large lens for the 
ciliary sulcus or a small lens for the capsular bag. 
A further advantage of the present invention is that the gentle force 
directed radially outwardly by the loops, and the compressibility of the 
loops, allow the lens to be placed equally advantageously whether both 
strands are located in the capsular bag, in the sulcus, or one strand in 
each. The gentle compression is less likely to tear the zonal 
suspensionary ligament of the human lens. 
Furthermore, the compressibility of the strands of the present invention 
require less intraocular manipulation to locate the lens properly within 
the eye. The lens of the present invention simply can be grasped by 
implantation forceps and be placed in one straight movement behind the 
iris into the ciliary sulcus or capsular bag. Thus, rotation of the lens, 
or "dialing", is unnecessary with the present invention. It is also easy 
to compress the loops in the forceps when inserting the lens, further 
simplifying straight-line insertion. The surgeon simply inserts the lens, 
places it in position and lets go. 
SUMMARY OF THE INVENTION 
The present invention is an intraocular lens for surgical implantation into 
the human eye, and comprises a lens body and two sinuous support strands 
each having at least one open loop portion. Each strand is attached to the 
lens body at diammetrically opposite locations on the periphery of the 
lens body. The loops are compressible radially with respect to the center 
of the lens for a substantial distance toward the center of the lens 
without substantially increasing the reaction force exerted outward toward 
the lens optic.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, there is shown in FIG. 2A a lens in 
accordance with the present invention generally indicated by the numeral 
10. The lens 10 comprises a lens body 12 to which are attached two support 
strands 14. The support strands 14, which have a sinuous, gently curving 
body, are attached to the lens body 12 at diammetrically opposite 
locations 16 on the periphery of the lens body 12. The extremities of 
strands 14 are provided with gently curving rounded ends 18 to minimize 
the possibility of damage to delicate eye tissue. The diameter of the lens 
body 12 defines the maximum lateral dimension of the support strands 14 in 
both the relaxed and compressed conditions. 
The support strands 14 comprise at least two generally parallel straight 
legs 17 which are straight for the major portion of their length and which 
are joined together at one end by a generally semicircular section 19. The 
embodiment illustrated in the drawings employs three legs 17 and it will 
be appreciated that any number of legs 17 may be employed. The legs 17 
define bight portions 15 at the ends opposite the semicircular section 19. 
Thus, the legs 17 and semicircular section 19 together form open loop 
portions 21. 
It will be observed that, unlike support strands of prior art lenses, the 
ends of support strands 14 are straight or flat due to straight legs 17. 
When the lens is inserted into the eye, the straight end forms a chord 
across the circle of the iris, thereby anchoring the support strand 14 and 
avoiding the need for rotating or "dialing" the lens into position. This 
feature of the lens 10 also makes it less susceptible to rotation about a 
diametric axis through support strands 14. 
The lens body 12 is made of a material suitable for sterilization and 
insertion into human tissue. Such lens materials are known in the art. The 
support strands 14 are made of polypropylene. Polypropylene is preferred 
because it has a specific gravity which is less than that of water. The 
amount of polypropylene in the support strands 14 is greater than the 
amount in other lenses because the support strands 14 have a longer total 
length than the support loops of prior art lenses. This makes the lens 10 
of the present invention lighter than prior art lenses. 
As shown in FIG. 2B, under compression the legs 17 move closer together. 
Thus, the loops formed by legs 17 and semicircular sections 19 compress 
radially with respect to the lens body 12. This enables the lens to be 
inserted straight into an incision without "dialing" to position the lens. 
Loops 14 compress along a radius which is angularly displaced from radii 
passing through diametrically opposed locations 16 where the loops 14 are 
attached to the lens body. The radius along which loops 14 are 
compressible is displaced from the closest of the radii through locations 
16 by about 45.degree.. 
While loop 14 is in its compressed state, its lateral dimension does not 
extend beyond the diameter of the lens body 12. This feature allows the 
surgeon to insert the lens 10 into the eye 24 with a single straight 
motion. 
As best seen in FIG. 3, lens body 12 consists of a convex portion 20 and a 
rim portion 22. The support strands 14 are attached to the rim portion 22 
at diammetrically opposite points 16. Support strands 14 are shown 
arranged to form an angle of approximately 10.degree. with the plane of 
the lens 12. As is known, the 10.degree. angle of the support strands 14 
to the plane of the lens provides added compressibility and keeps the lens 
optic well back from contact with the iris. The lens may also be 
constructed so that the support strands 14 are in the same plane as the 
lens; i.e., the angle of the support strands 14 to the plane of the lens 
may be zero. However, a 10.degree. angle is preferred. Providing a 
10.degree. angle between support strands and lens plane is known in the 
art. 
The radial length of the loops 21 should be only slightly greater than the 
diameter of the lens. The width of the loops 21 from side to side should 
not exceed the lens diameter so that the lens can be inserted straight 
into a minimum-sized incision. 
FIGS. 4, 5 and 6 illustrate the placement of lens 10 in the eye 24. As 
shown in FIG. 4, the outer structure of the eye consists of the sclera 26 
and the cornea 32, which together form the outer surface of the eye. The 
iris 34 defines the pupil or pupilary cavity 36, through which light is 
admitted to the interior of the eye and the retina (not shown). In FIG. 4, 
lens 10 is located so that support strands 14 rest in the ciliary sulcus 
30, which is formed by the ciliary body 28. Since both support strands 14 
are equally compressible, the lens automatically centers itself so that 
the optical axis of the lens coincides with the optical axis of the eye. 
FIG. 5 illustrates lens 10 located in the capsular bag 40. It can be seen 
that, in comparison to FIG. 4, the support strands 14 are compressed 
greater when the lens 10 is placed in the capsular bag 40. However, 
because of the sinuous shape of support strands 14, the force exerted by 
support strands 14 against the capsular bag 40 is quite gentle. As 
described above, since both support strands 14 are equally compressible, 
lens 10 automatically aligns its optical axis with the optical axis of the 
eye. 
FIG. 6 illustrates lens 10 located such that one support strand 14 is 
located in the capsular bag 40 while the other support strand 14 is 
located in the ciliary sulcus 30. Ordinarily, such an implantation would 
be disadvantageous in that the optical axis of the lens would not 
correspond to the optical axis of the eye because each of the support 
strands is compressed to a different degree, and therefore would exert a 
different reaction force on the lens. However, the sinuous shape of the 
support strands 14 in the present invention causes the strands 14 to exert 
virtually constant reaction forces regardless of the degree to which they 
are compressed. Thus, in spite of one support strand 14 being located in 
the capsular bag 40 and the other in the ciliary sulcus 30, both exert 
almost equal reaction forces and thus the lens 10 is automatically almost 
centered so that the optical axis of the lens 10 corresponds closely to 
the optical axis of the eye. 
It is believed that only 0.5 mm to 1.0 mm decentration results even if one 
strand is in the capsular bag and the other is in the sulcus. 
It will be appreciated that the invention provides an intraocular lens 
which is gentle on eye tissue, easily compressible and quite stable in 
position. The lens also includes more polypropylene than other lenses 
which makes its density very close to that of the aqueous material in the 
eye. The lens, moreover, centers well and does not have to be rotated into 
place. 
The present invention may be embodied in other specific forms without 
departing from the spirit or essential attributes thereof and, 
accordingly, reference should be made to the appended claims, rather than 
to the foregoing specification, as indicating the scope of the invention.