Interventions for preventing posterior capsule opacification

Posterior capsule opacification (PCO) is the most common long-term complication after cataract surgery with implantation of an intraocular lens (IOL). It can be treated by cutting a hole in the posterior lens capsule with an Nd:YAG laser (Neodymium:YAG laser capsulotomy), however this procedure may lead to other complications. It is also expensive and not available in large parts of the developing world. Therefore, many studies have been performed to investigate the pathogenesis of PCO and to find possible ways of preventing it. This review included 66 prospective, randomised, controlled trials assessing the effect of different interventions on PCO. These interventions included modifications in surgical technique explicitly to inhibit PCO, modifications in IOL design (material and geometry), implantation of additional devices and pharmacological therapy compared to each other, placebo or standard treatment. All trials had a follow-up time of at least 12 months. The effect of the intervention on PCO was assessed by measuring visual acuity, (subjective or objective) PCO score and the number of performed Nd:YAG laser capsulotomies. The results of the review were divided into three parts. In part one (effect of IOL material on PCO), the meta-analysis of the included trials found no significant differences in the PCO scores between different IOL materials. In part two (effect of IOL geometry), the meta-analysis showed significantly lower PCO rates in IOLs with sharp posterior optic edges than in IOLs with round optic edges. However, there was no difference between 1-piece and 3-piece IOLs. In part three (influence of surgical technique and drugs on PCO), one trial found a lower PCO rate in IOLs placed in the capsular bag compared to IOLs placed in the sulcus. Another study found a lower PCO rate in eyes with a small capsulorhexis compared to a large capsulorhexis. Where drugs were concerned, only treatment with an immunotoxin led to significantly less PCO in two studies. In summary, primarily the choice of the IOL geometry seems to have a significant influence on the development of PCO. Therefore, IOLs with sharp optic edges should be preferred.