In vivo fracture of an extruded polymethylmethacrylate intraocular lens loop.

The inferior loop of a semiflexible, closed-loop anterior chamber intraocular lens in the eye of a 72-year-old female fractured at two sites. The loop was composed of extruded polymethylmethacrylate. The inferotemporal portion of the loop was first noted to be broken 25 months postoperatively, and the fractured nasal portion of the same loop was first observed 55 months after implantation. The patient denied any excessive rubbing of the eye or major trauma to the eye or head. Both fractures occurred near the loop-optic junction. The intermittent touch of the cornea by the broken loop caused endothelial damage and edema in the lower one third of the cornea. The two portions of the lens were removed and exchanged with another style of anterior chamber lens. The visual acuity at six weeks postexchange was 20/30.

Anterior chamber lenses. Part II: A laboratory study.

An analysis of 606 surgically removed anterior chamber intraocular lens (IOL) specimens revealed that 351 or 58% of these were small-diameter, round loop, closed-loop styles. Because of the extremely high percentage of IOLs with this design received in our laboratory and the correlation of clinical histories with our histopathologic findings, we have concluded that such IOLs do not provide the safety and efficacy achieved by other anterior chamber lens designs. The finely polished, one-piece, all-PMMA styles fared well in our study. Although these one-piece styles comprise well over 50% of the American market share of anterior chamber IOLs, they comprise only 14% of all anterior chamber IOLs accessioned in our laboratory, compared to 58% for closed-loop designs. We believe that implantation of anterior chamber lenses with small-diameter, round, closed loops is no longer warranted. Patients in whom these IOLs have already been implanted should be carefully followed. It is our opinion that the FDA should recall or closely monitor all IOLs of this design and that implantation of closed-loop lenses should be discontinued in the United States. Furthermore, we believe that an IOL deemed to be not medically sound or worthy of implantation in the United States should not be marketed or donated outside of this country.

Posterior chamber intraocular lenses in a series of 75 autopsy eyes. Part II: Postimplantation loop configuration.

We illustrate, from the pathologist's viewpoint, the configuration of posterior chamber lens loops within the eye. The final configuration of these loops is often a "C" shape, particularly following capsular fixation. When one or both loops are placed in the ciliary sulcus, where tissue resistance to loop compressive forces is less than in the capsular sac, an invagination or erosion of the loop into the ciliary body stroma or ciliary muscle frequently occurs. Although a surgeon should first and foremost choose a lens design with which he or she is comfortable in terms of ease of implantation and good clinical results, our pathological observations indicate that a subtle compromise in loop configuration might provide a more physiologically correct configuration in the eye, particularly for those who prefer in-the-bag implantation. Most surgeons prefer a lens design that will provide adequate fixation in the ciliary sulcus if an attempted capsular sac implantation is not successful.

Posterior chamber intraocular lenses in a series of 75 autopsy eyes. Part III: Correlation of positioning holes and optic edges with the pupillary aperture and visual axis.

The possibility that undesirable visual complications such as glare, halo, monocular diplopia, or other visual aberrations can result from the presence of posterior chamber lens optic edges or such lens elements as positioning holes or loop-optic junctions within the pupillary aperture has received little attention. There is recent clinical evidence that these phenomena may be clinically significant. In a series of 75 autopsy eyes with posterior chamber intraocular lenses, we have observed that in 71% of cases an optic edge, or element of the optic such as a positioning hole, was situated either within the pupillary aperture and visual axis (average pupillary diameter 3.45 mm) or within 0.5 mm of the pupillary margin. This finding was most common (92%) in cases with asymmetric placement, less common (50%) in cases with symmetric placement. Many more young patients are now undergoing implantation surgery. These patients generally have wider, more mobile pupils, and they may be more aware of subjective symptoms, particularly at night. Subtle changes in implantation techniques and in lens design and manufacture can minimize complications related to this condition. These changes include symmetric loop placement (both loops in the capsular sac or both in the ciliary sulcus) to decrease optic decentration. Other measures such as making partial-depth positioning holes, increasing the size of the optic, eliminating or reducing the number of positioning holes, and placing positioning holes in tabs on the optic edges may function to increase the effective optical zone.