An intra-ocular lens for implanting into the posterior capsule after cataract extraction, has a pair of sinuous haptics having greater flexibility near their roots than at their distal ends. A long arcuate distal segment of each haptic espouses the internal radius of the posterior capsule over an arc of at least 15 degrees. Both haptics have a slight backward slant. The haptics facilitate the implantation and retention of the lens.

FIELD OF THE INVENTION 
This invention relates to extra-ocular lens prosthesis which are commonly 
installed after an intra-capsular cataract extraction into the posterior 
chamber or into the capsular bag. More specifically, this invention 
relates to the fixation appendages or haptics associated with the 
intra-ocular lens. 
BACKGROUND OF THE INVENTION 
As part of the surgical procedure commonly known as extracapsular cataract 
extraction, during which the anterior capsule is extracted with the lens 
and the posterior capsule is drained but left intact, an artificial lens 
is installed into the posterior capsule. As illustrated in FIGS. 1-3, the 
artificial intra-ocular lens (IOL) 1 is provided with two integrally 
formed appendages or haptics 2,3 which are designed to centrally mount the 
IOL while nesting into the inner peripheral rim 4 of the posterior 
capsule. It is estimated that in half of such surgical interventions, one 
of the haptics 2, 3 is not retained into the rim of the posterior capsule 
by its anterior flaps 5 and instead bears against the ciliary sulcus 6, or 
is erroneously implanted in that position, as illustrated in FIG. 1. This 
asymmetrical position of the IOL results in a decentration whereby the 
axis XX' of the IOL is shifted away from the actual axis Y--Y' of the eye. 
There results a loss of visual acuity which often evades the attention of 
the ophthalmologist. 
SUMMARY OF THE INVENTION 
The principal and secondary objects of this invention are to reduce or 
eliminate the risk of eccentric installation or movement of an IOL 
installed in the posterior capsule; and to facilitate the manipulation of 
the IOL and its placement in the posterior capsule. 
These and other objects are achieved by increasing the lengths and 
sinuosity of the haptics and providing for a stiffer resistance to bending 
in their distal portions, as well as angling the haptics backward from the 
vertical axis of the IOL.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
The preferred embodiment of the invention is illustrated in FIGS. 4 and 5. 
An intraocular lens (IOL) 7 of generally same shape and dimensions as the 
IOL of the prior art has a pair of integrally formed haptics 8, 9 
projecting from diametrically opposed points on the periphery of the IOL. 
Each haptic is formed into a sinuous curve and characterized by a 
difference in thickness and consequently in flexibility between sections. 
In this embodiment a proximal section 10, 11 near its root on the IOL has 
a substantially smaller cross-section than the cross-section of a distal 
portion 12, 13. The distal section 12, 13 describes an arc of at least 15 
degrees at a constant radius R corresponding to the radius of the 
posterior capsule into which the IOL is to be mounted. The preferred 
embodiment is further characterized by a backward slanting at the haptics 
by an angle B in a range of 3 to 15 degrees. In this embodiment, each 
haptic has a continuously increasing cross-section as it extends away from 
the optic. The variations in the cross-section results in a higher degree 
of flexibility of any portion of the haptic closer to the optic as 
compared to a more distal portion. 
The just described configuration of the haptics facilitates the 
installation of the IOL into the capsular bag and greatly increases its 
stability. When, during installation, the haptics are compressed to clear 
the flaps 5 of the posterior capsule illustrated in FIG. 1, the proximal 
section 10 flexes first without substantial deformation of the more distal 
sections 12, 13. This phenomenon accounts for a more convenient handling 
and manipulation of the IOL into the posterior capsule. Once installed, 
the more rigid distal sections 12, 13 retain their common radius R with 
the interior of the capsule, and through their extended length and 
increased thickness, present a substantially larger contact area with the 
interior rim 4 of the posterior capsule. The increased friction between 
the haptics and the lining of the posterior capsule assure a more stable 
placement of the prosthesis. The slight backward angle B of the haptics 
places the optic in the very center of the posterior capsule where it is 
less likely to be contacted by its posterior wall and knocked out of 
alignment as frequently occurred with devices of the prior art. 
In the first alternate configuration of the haptic 14 diagrammatically 
illustrated in FIG. 6, the general arcuate shape common to the haptics of 
the prior art has been retained, but the stiffer distal portion 15 
espouses the radius of curvature R of the posterior capsule 16 over an arc 
A of no less than 15 degrees. 
In the second and third alternate embodiments 17, 18 illustrated in FIGS. 7 
and 8, the haptics are characterized by a first linear, proximal section 
19, 20 of relatively low flexibility, followed by an arcuate section 21, 
22 with the same characteristics as the first embodiment, i.e. decreasing 
flexibility, common radius of curvature, and increased contact arc with 
the rim of the posterior capsule 16. In the fourth alternate embodiment 
23, the haptics are not built integrally with the optic 24 but are made 
from a different material and implanted therein. 
The haptic segment 25 illustrated in FIG. 10 has a portion 26 with an 
arcuate cross-section reinforced by a radial rib 27. The variation in 
flexibility can be achieved by variations in the width or thickness of the 
radial rib 27 in lieu of, or in addition to, variations in the thickness 
and width of the arcuate portion 26. It should also be noted that the 
difference between the flexibility of the proximal and distal portions 
need not necessarily be progressive and could be achieved by a sudden 
transition at mid-length of the haptic. Such a difference in the 
flexibility of the two segments of the haptics can be achieved by use of 
different materials while keeping a constant cross-section along the 
entire length of the haptic. 
While the preferred embodiments of the invention have been described, 
modifications can be made and other embodiments may be devised without 
departing from the spirit of the invention and the scope of the appended 
claims.