Square Edge Intraocular Lens Versus Conventional Round Edge Intraocular Lens in Prevention of Posterior Capsule Opacification—A Randomized Controlled Trial at KLE’S Dr. Prabhakar Kore Hospital

Abstract

BACKGROUND AND OBJECTIVES: ABSTRACT Posterior capsule opacification is the most common complication after cataract surgery occurring in up to 50% of patients and is associated with decreased vision. It can be treated by Nd:YAG ( neodymium-doped yttrium aluminium garnet ) laser capsulotomy, which, however, can cause complications such as retinal detachment, endophthalmitis and raised intraocular pressure. In developing countries like India Nd:YAG laser capsulotomy puts additional economical burden on patients. Recent trials have showed that in the context of phacoemulsification, intraocular lens design has a significant influence on posterior capsule opacification rates, with square edge profile lens having lower rates of posterior capsule opacification ( 10% at the end of one year ) than conventional round edge lens. This study is undertaken to determine whether square edge polymethylmethacrylate ( PMMA ) intraocular lens is superior in preventing clinically significant posterior capsule opacification and better visual outcome when compared with conventional round edge PMMA intraocular lens in context of manual small incision cataract surgery in a developing country. METHODOLOGY: The present randomized clinical trial was conducted at KLES Dr.Prabhakar Kore Hospital and Medical Research Centre, Belgaum, over a period of one year, from 1 st January 2009 to 31 st December 2009. In the study, 128 patients were included, who met the inclusion criteria. After detailed evaluation, informed consent was taken and they were randomized into two groups to receive either round edge IV intraocular lens ( Group A ) or square edge intraocular lens ( Group B ) after manual small incision cataract surgery. All patients completed the study with a minimum follow up of 10 months. A detailed documentation of best corrected visual acuity, grades and type of posterior capsule opacification was done during follow up. OBSERVATION AND RESULTS: The majority of patients in our study were in the age group of 60-69 years ( 39.8% ) . Mean age in Group A was 62.7 years and in Group B was 62.8 years. Male to female ratio was 1:1.06. Out of 128 patients overall incidence of posterior capsule opacification was 83.6%, in which 85.9% were in Group A and 81.2% were in group B. The Grade 3( Posterior capsule opacification well inside intraocular lens edge but clear visual axis) and Grade 4( Posterior capsule opacification across visual axis ) posterior capsule opacification which we considered as clinically significant was seen in 37.5% patients in Group A and 17.2% patients in Group B. The difference between the two groups was statistically not significant (  clinically significant. V 2 = 6.900, DF = 3, p=0.075) , but Visual outcome was better in Group B which was statistically significant ( 0.003) . Fibrous type of posterior capsule opacification was the commonest type seen in our study irrespective of the groups. There was less incidence of posterior capsule opacification in capsulorrhexis ( with relieving incisions) and complete cortical clean up cases. The difference in Nd:YAG laser capsulotomy rates were not statistically significant between the two groups (  p=0.784) 2 with Yates’ correction = 0.075, DF = 1, CONCLUSION: From our study we conclude that square edge PMMA intraocular lens gave less clinically significant posterior capsule opacification rates and better visual outcome when compared to round edge PMMA intraocular lens.