Effect of intraocular lens edge profile on posterior capsule opacification after extracapsular cataract surgery in a developing country

Abstract

Purpose: To determine whether square-edged polymethyl methacrylate (PMMA) intraocular lenses (IOLs) reduce posterior capsule opacification (PCO) in the context of extracapsular cataract surgery in a developing country.

Setting: A rural hospital in India.

Methods: This was a prospective randomized double-masked fellow-eye controlled study. Over a 4-month period, 118 patients with normal eyes apart from age-related cataract were randomized to receive a square-edged or round-edged PMMA IOL in the first eye. The IOLs were identical apart from the edge profile. The fellow-eye had implantation of the alternative IOL within 1 month. Retroillumination images of the posterior capsule were taken using a dedicated camera system and analyzed to quantify the PCO area using POCO software 1 and 2 years postoperatively and the PCO area and severity using POCOman semiqualitative software at 2 years. Visual acuity was measured using a Gujarati logMAR chart.

Results: One hundred fifteen patients were available for examination at 1 year and 107 at 2 years. With POCO software, the PCO area was reduced in the square-edged IOL group at 1 year (median 30% versus 20%, P=.001) and at 2 years (median 45% versus 35%, P=.006). With POCOman, the PCO area and severity were reduced in the square-edged group at 2 years (median 41.5% versus 33.2%, P=.019 and 0.59 versus 0.46, P=.037, respectively). There was no significant difference in visual acuity between the 2 groups at 1 or 2 years.

Conclusions: Sophisticated image analysis techniques can be used in developing countries to quantify PCO. Using extracapsular surgery, square-edged PMMA IOLs reduced the PCO area and severity compared with an identical round-edged IOL; however, the differences were not as marked as those reported with phacoemulsification. This may be due to the difficulty of performing a capsulorhexis that lies on the IOL surface in this situation. Nevertheless, square-edged IOLs offer a potential benefit for extracapsular surgery in the developing world.