Iris Crypts are Protective for Acute Primary Angle Closure

Abstract

Purpose : We aimed to determine the relationship between iris surface features and past attack of acute primary angle closure (APAC) in eyes with angle closure.

Methods : This was a case-control study involving Asian patients diagnosed with previous APAC, primary angle closure suspect (PACS), and primary angle closure (PAC) at a tertiary eye centre in Singapore between August 2012 and January 2015. All participants underwent a standardized ophthalmic examination and digital slit-lamp iris photography. Iris surface features were graded based on crypts (by number and size), furrows (by number and circumferential extent) and color. The fellow eyes of APAC were used as proxies for APAC eyes to compared with PACS/PAC eyes with regards to their iris surface features, as the post-attack APAC eye frequently had structural iris changes and altered iris surface architecture.

Results : A total of 71 patients with APAC and 186 with PACS or PAC were included in the analysis (mean age: 68.0 ± 7.2 years and 32.7% male). Higher grade of iris crypts were significantly associated with lower risk of APAC occurrence (OR = 0.54 for one grade higher in crypt grade; P = 0.013, adjusted for age, gender, ethnicity and pupil size). That is, having one grade more in the iris crypt reduced the likelihood of having APAC by almost 50%. We did not observe significant associations between iris furrows or iris color with presence of APAC (both P > 0.05).

Conclusions : Our study comprising Asian eyes with angle closure suggests that the presence of numerous and larger crypts may be protective for APAC. As such, assessing iris surface architecture for iris crypts grade could be a new measure for risk stratification of developing APAC in eyes with angle closure.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.