Population-based analysis of intraocular lens exchange and repositioning

Abstract

We read the article by Szigiato et al.1 with interest, and we believe that some further discussion might be of benefit. The authors present a data-analysis study to determine the incidence and trends in intraocular lens (IOL) repositioning, exchange, and explantation in Ontario, Canada. Their Figure 2 presents the cumulative risk for secondary procedures after cataract surgery, reaching 2.84% in the 5-year period in the patients younger than 45 years. Most of the secondary procedures during the 5-year period were performed in the first year after cataract surgery, with the highest rate of 60.29% in women. These results are in contrast to those of Dabrowska-Kloda et al.,2 who reported a very low IOL dislocation risk during the first 3 years after surgery in Sweden. The cumulative risk 5 years, 10 years, 15 years, and 20 years after cataract surgery was 0.09%, 0.55%, 1.00%, and 1.00%, respectively. How would the authors explain these differences? Furthermore, posterior chamber IOL subluxation or dislocation can be divided into early cases (up to 3 months after cataract surgery) and late cases (3 or more months after surgery). This categorization is essential because tearing of the posterior capsule and rupture of the equatorial zonule is a predisposing factor for early dislocation. Late dislocation is associated with progressive zonular insufficiency and capsular bag contraction, with pseudoexfoliation syndrome as the most common risk factor.3 Would it be possible to assess the data within these timeframes because doing so could lead to additional conclusions? The authors found a 75.6% increase in secondary procedures from 713 performed in 2000 to 1252 in 2013. Dabrowska-Kloda et al.2 state that the increasing number of late in-the-bag IOL dislocations cannot be explained by the growing pseudophakic population only. The increase in the incidence was primarily the result of the longer duration of pseudophakia in the population and to a greater dislocation risk with recent cataract surgery. The optimum management for late in-the-bag IOL dislocation is still being questioned. The authors found that from 2000 to 2013, sutured repositionings and explantations increased by 568% and 531%, respectively, whereas exchanges without suturing decreased by 22.6%. This issue is particularly interesting because of the development of open-loop haptic anterior chamber IOLs and the introduction of iris-claw IOLs; both IOL types have shown their efficacy in the overwhelming majority of such cases. In a recent study, Kristianslund et al.4 compared the efficacy and safety of IOL repositioning by scleral suturing versus IOL exchange with an iris-claw IOL. The group comparison showed that IOL repositioning had a longer surgical time and a tendency toward more intraocular hemorrhage, whereas IOL exchange required more anterior vitrectomies or removal of vitreous strands from the incision and such patients had more iris injuries. Both operations were found to be safe with few serious complications and no significantly different outcomes in corrected visual acuity 6 months after surgery. Furthermore, with proper IOL calculation, it is possible to achieve ±1.00 diopter of postoperative spherical equivalent in up to 100% of cases.5