Pseudoexfoliation may play greater role in late IOL subluxation/dislocation

Take-home message: Histopathologic analysis of 53 consecutive IOL-capsular bag specimens explanted after late in-the-bag IOL subluxation/dislocation identified pseudoexfoliation in 33(62%) of cases-less than half of which had a clinical diagnosis of pseudoexfoliation.

By Cheryl Guttman Krader; Reviewed by Nick Mamalis, MD

Salt Lake City-Pseudoexfoliation is an important risk factor for late spontaneous IOL subluxation/dislocation, according to findings from a histopathologic study.

In addition, research indicates that because of significant clinical underdiagnosis, pseudoexfoliation may be responsible for more of these complications than previously thought.

The study was conducted at the Intermountain Ocular Research Center, John A. Moran Eye Center, University of Utah, Salt Lake City, where 53 consecutively explanted specimens from 53 patients were examined. The explantations were provided by two surgeons from Goethe-University, Frankfurt, Germany, and occurred from December 2011 to February 2014.

A variety of IOL materials and designs were represented, and in three specimens, there was an IOL and capsular tension ring (CTR).

Based on complete histopathological analysis, 33 (62%) of the 53 explanted capsular bags had evidence of pseudoexfoliation. Review of corresponding charts from the latter cases showed clinical evidence of pseudoexfoliation for only 16 (48.5%) of the 33 eyes.

Recognizing pseudoexfoliation

“Our findings indicate that all types of IOLs are susceptible to late spontaneous dislocation and that a CTR is not protective,” said Nick Mamalis, MD, professor of ophthalmology, John A. Moran Eye Center, and co-director, Intermountain Ocular Research Center. “However, when pseudoexfoliation is recognized preoperatively, surgeons can implement measures intraoperatively and postoperatively that may reduce the risk of late IOL dislocation/subluxation.

“The first step, however, is to recognize pseudoexfoliation,” he said. “Careful preoperative evaluation is critical because pseudoexfoliation may be subtle and difficult to diagnose.”

Dr. Mamalis’ laboratory often receives IOLs removed due to dislocation, but sometimes they do not receive the capsular bag, he noted.

In a paper published in 2009, Dr. Mamalis and colleagues reported finding a clinical history of pseudoexfoliation in 50% of 86 late dislocated IOLs they analyzed [Davis D, et al. Ophthalmology. 2009;116:664-670]. None of those cases had a CTR, but in a follow-up study including only specimens with a CTR, 74% were from patients with a history of pseudoexfoliation [Werner L, et al. Ophthalmology. 2012;119:266-271].

In contrast to those investigations, the intact capsular bag was available for all specimens in the current study, allowing evaluation for signs of pseudoexfoliation on the capsular bag.

“We suspected that the incidence of pseudoexfoliation among cases of late spontaneous IOL dislocation/subluxation was higher than what we were finding before,” Dr. Mamalis said. “Access to the capsular bag for all cases in the current series allowed us to get a better idea of the true incidence.”

Patients from whom the specimens were obtained had a mean age of 77 years, and the majority was from women. Mean time to explantation for the 53 specimens was 12.2 years. Types of IOLs in the study included 1- and 3-piece hydrophobic acrylic and hydrophilic acrylic lenses, as well as 3-piece silicone IOLs and 1-piece PMMA IOLs.

Histologic evidence of pseudoexfoliation material in the current study was based on identification by an observer masked to clinical diagnosis of an amorphous substance on the outer surface of the anterior lens capsule in an “iron-filing” pattern.

Macroscopic, microscopic, and photographic examination of the specimens was also performed prior to processing for histopathological analysis and showed evidence of excessive capsular contraction/phimosis in 28 specimens and moderate to severe Soemerring’s ring formation in 42 specimens.

Preventive strategies

Measures to reduce the risk of late in-the-bag IOL dislocation in eyes diagnosed preoperatively with pseudoexfoliation include creation of a generously sized capsulotomy and careful surgical technique to minimize zonular stress.

In addition, careful follow-up is indicated to allow early detection of anterior capsule phimosis and intervention with Nd:YAG laser relaxing anterior capsulotomy incisions before there is significant contraction affecting the zonules.

Dr. Mamalis also mentioned another recently published paper in which surgeons reported placing microhook iris retractors to fixate the capsulorhexis, a CTR in the capsular bag, and performing optic capture of a sulcus-placed foldable multipiece acrylic IOL in eyes deemed at risk for late in-the-bag dislocation because of zonular weakness [Devranoğlu K, et al. J Cataract Refract Surg. 2013;39:669-672].

Nick Mamalis, MD

E: nick.mamalis@hsc.utah.edu

This article is adapted from Dr. Mamalis’ presentation at the 2015 meeting of the American Society of Cataract and Refractive Surgery, which was an update to a published report based on 40 specimens [Liu E, et al. J Cataract Refract Surg. 2015;41:929-935]. Dr. Mamalis is a consultant/advisor for companies that market IOLs.