Estimation of mean ND: Yag laser capsulotomy energy levels for membranous and fibrous posterior capsular opacification.

INTRODUCTION

Posterior capsule opacification (PCO) is a visually-disabling complication of cataract surgery.

OBJECTIVE

To estimate energy levels for capsulotomy in various subtypes of PCO (membranous, fibrous and fibro-membranous).

MATERIALS AND METHODS

A total of 215 patients with PCO were randomly selected and evaluated for Nd: Yag laser capsulotomy, after a quiet post-operative course of 3 months.The ocular area was arbitrarily divided into three zones: YAG zone (3mm), Optical zone (6mm) and the peripheral zone (12mm). A colour code was assigned to the subtype of PCO in these zones: fibrous green and membranous blue. The type of PCO in each quadrant of YAG zone was estimated in percentage.

RESULTS

The statistic mean values of initial energy levels were 1.80 mJ for membranous PCO, 3.17 mJ for fibrous PCO and 2.73 mJ for fibro-membranous PCO. The mean summated energy levels for membranous PCO was 22.80 mJ for membranous PCO, 80.06 mJ for fibrous PCO and 80.48 mJ for fibro-membranous type.

CONCLUSION

Colour coding is extremely helpful for quantification of the type of PCO and in deciding the initial energy level necessary to create capsulotomy. Fibro-membranous PCO required more summated energy despite a lower starting energy. Therefore, we recommend firing the initial shot in fibrous portion in case of fibrous-membranous type of PCO.