Long-term safety of YAG laser iridotomy on corneal endothelium in angle-closure suspects

A 72-month randomized controlled study looked at the long-term effects of laser iridotomy on corneal endothelium in primary angle-closure suspects.

Study design

This was a single center randomized controlled study of 875 patients suspected of bilateral primary angle closure (PACS). Patients received YAG laser iridotomy randomly in one eye, and the other eye served as a control. Central endothelial cell density (ECD) and morphology were evaluated at baseline as well as at 6, 18, 36, 54, and 72 months post-laser. This work is part of the Zhongshan Angle Closure Prevention Trial.

Outcomes

Both control eyes and those receiving laser had a significant decline in ECD and cell morphological changes. Laser-treated eyes showed only a small but statistically significant decline compared with control eyes at 72 months only, but at no time points prior. At 72 months there was a 4.93% decline in the treated eye and a 4.2% decline in untreated control eyes (p = 0.003). There was no association found between total laser energy used and level of endothelial cell loss.

Limitations

Laser iridotomies are performed in the periphery and may cause more peripheral endothelial cell damage as opposed to central cell loss and morphological changes. This study did not evaluate the peripheral cornea. Corneal thickness was not measured at baseline or at subsequent visits. It's possible that the small increase cell loss at 72 months would lead to subclinical corneal thickening/edema, though this is unlikely given the <1% difference between treated and control eyes.

Clinical significance

There is contradictory evidence in the literature regarding the effect of laser iridotomies on corneal endothelial cells. This study is randomized, has a contralateral control eye, and has good long-term follow-up. This study gives added reassurance to the safety of YAG laser iridotomies in PAC suspects.