Effect of Prophylactic Laser Iridotomy on the Corneal Endothelium in Eyes With Narrow Drainage Angles

Abstract

Purpose: : To assess the effect of prophylactic laser iridotomy (LI) on corneal endothelial cell counts in a cohort of primary angle closure suspects (PACS).

Methods: : As part of a randomized controlled trial, subjects over the age of 50 years and diagnosed as PACS in both eyes underwent prophylactic LI in one eye, while the fellow eye served as a control. PACS was defined as the presence of appositional contact between the iris and posterior trabecular meshwork for at least 180º on gonioscopy, with intraocular pressure ≤ 21 mm Hg, and absence of peripheral anterior synechiae, glaucomatous optic neuropathy or visual field changes compatible with glaucoma. The central corneal endothelium of both eyes of all subjects were assessed using a non-contact specular microscope (Konan Noncon Robo SP-9000LC) at baseline and 1 year later. Only those eyes that had measurements on the same device were included.

Results: : A total of 155 PACS subjects were included. The mean age was 63.3 ± 6.7 (50-87) years. The majority of subjects were Chinese (93%) and female (72%). In eyes that underwent LI, the endothelial cell density was lower at year 1 (2419.2 ± 383.7 cells/mm²) when compared to baseline (2764.5 ± 386.6 cells/mm²) (p<0.05). There was also a decrease in endothelial cell density in the fellow untreated eye from baseline (2738.3 ± 408.3 cells/mm²) to year 1 (2399.8 ± 402.1 cells/mm²) (p<0.05). There was no significant difference in the percentage decrease in cell density in eyes that underwent LI (11.5%) as compared to fellow eyes (11.3%) (p=0.88).

Conclusions: : In this cohort of PACS eyes, there were lower endothelial cell counts in both LI treated and control eyes after one year, but the percentage reduction was similar in both groups. The long term effects of LI on the corneal endothelium needs to be assessed.

Keywords: laser • cornea: endothelium