Decentration of flexible loop posterior chamber intraocular lenses in a series of 222 postmortem eyes.

Two hundred twenty-two postmortem eyes containing posterior chamber intraocular lenses (IOLs) were analyzed for optic decentration in relationship to lens style, implant duration, and loop fixation site. Decentration values were not affected significantly by either lens style or implant duration. In 33.3% of specimens, both loops were situated within the lens capsular sac, 18.0% had both loops fixated in the ciliary sulcus, and in 48.7% one loop was fixated in the lens capsular sac and the opposite loop in the ciliary sulcus or zonular region. There was a statistically significant difference in the amount of decentration in the three fixation groups studied. Capsular fixation provides the best and most consistent centration compared with fixation of both loops in the ciliary sulcus or asymmetrical fixation with only one loop in the capsular sac.

Visual aberrations caused by optic components of posterior chamber intraocular lenses.

A 58-year-old airline pilot had cataract surgery with implantation of a posterior chamber intraocular lens with four positioning holes around the optic edge. During periods of maximum pupil dilation, such as at night, visual aberrations including glare, monocular diplopia, and haloes occurred and he was unable to work in his occupation. The symptoms were severe enough that lens exchange was required, and a posterior chamber lens with no positioning holes was successfully implanted. The symptoms immediately subsided postoperatively and his last known visual acuity was 20/15. This case, and the report of another patient with similar postoperative problems, illustrates that implantation of lens optics with a larger effective optical zone for posterior chamber lens implantation is desirable. This is particularly true now that younger, more active patients, many still engaged in occupations, are having lens implantations.

Anterior chamber lenses. Part I: Complications and pathology and a review of designs.

Clinicopathologic data to assist ophthalmologists in choosing a safe and efficacious anterior chamber intraocular lens (IOL) are rapidly becoming available. Two important factors that have led to an increased success rate with some anterior chamber IOL styles are (1) attention to lens design and (2) attention to modern manufacturing and lens finishing techniques. We now know much more about how to achieve appropriate lens flexibility, which decreases the need for perfect sizing. Increased attention has been given to the anterior-posterior vaulting characteristics of IOLs. This has reduced the incidence of various complications such as the intermittent touch syndrome and the uveal chafing syndrome. We recognize several design flaws in some lens styles. For example, there is now a considerable decrease in the number of small-diameter, round-looped anterior chamber IOLs being implanted, particularly those with a closed-loop configuration. Several problems have been and continue to be caused by some poorly manufactured anterior chamber lenses with sharp optic and haptic edges. Technology to assure smooth lens finishing and polishing is available and readily accessible to all manufacturers. Defective lenses should soon be a thing of the past.

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.

Posterior chamber intraocular lenses in a series of 75 autopsy eyes. Part I: Loop location.

Over a period of 27 months, November 1983 to February 1986, 75 eyes obtained postmortem with posterior chamber intraocular lenses (IOLs) were examined at the Center for Intraocular Lens Research, University of Utah Health Sciences Center. These IOLs were studied by histopathological techniques to determine the location of the loops. The most common combination, found in 47% of the specimens, was one loop in the lens capsular sac (bag) and one loop in the ciliary sulcus. In 32% of the specimens, both loops were in the capsular sac; in 17%, both loops were in the ciliary sulcus. Compared to results observed in other autopsy studies, in which capsular fixation was documented in less than 3% of cases, these findings reflect a trend toward capsular sac (in-the-bag) implantation of open-looped posterior chamber IOLs.