Investigating the determinants of iridolenticular contact area: a novel parameter for angle closure.
Tun Tin A, Nongpiur Monisha Esther, Xu Benjamin Y, Wang Xiaofei, Tan Marcus, Quah Joanne Hui Min, Lim Hou-Boon, Cheng Ching Yu, Aung Tin
AI Summary
This study found iridolenticular contact area (ILCA) is smaller in angle closure eyes and independently predicts angle closure, offering a novel biometric risk factor related to pupillary block.
Abstract
Background/aims: To identify ocular determinants of iridolenticular contact area (ILCA), a recently introduced swept-source optical coherence tomography (SSOCT) derived parameter, and assess the association between ILCA and angle closure.
Methods
In this population-based cross-sectional study, right eyes of 464 subjects underwent SSOCT (SS-1000, CASIA, Tomey Corporation, Nagoya, Japan) imaging in the dark. Eight out of 128 cross-sectional images (evenly spaced 22.5° apart) were selected for analysis. Matlab (Matworks, Massachusetts, USA) was used to measure ILCA, defined as the circumferential extent of contact area between the pigmented iris epithelium and anterior lens surface. Gonioscopic angle closure (GAC) was defined as non-visibility of the posterior trabecular meshwork in two or more angle quadrants.
Results
The mean age of subjects was 62±6.6 years, with the majority being female (65.5%). 143/464 subjects (28.6%) had GAC. In multivariable linear regression analysis, ILCA was significantly associated with anterior chamber width (β=1.03, p=0.003), pupillary diameter (β=-1.9, p<0.001) and iris curvature (β=-17.35, p<0.001). ILCA was smaller in eyes with GAC compared with those with open angles (4.28±1.6 mm 2 vs 6.02±2.71 mm 2 , p<0.001). ILCA was independently associated with GAC (β=-0.03, p<0.001), iridotrabecular contact index (β=-6.82, p<0.001) or angle opening distance (β=0.02, p<0.001) after adjusting for covariates. The diagnostic performance of ILCA for detecting GAC was acceptable (AUC=0.69).
Conclusions
ILCA is a significant predictor of angle closure independent of other biometric factors and may reflect unique anatomical information associated with pupillary block. ILCA represents a novel biometric risk factor in eyes with angle closure.
MeSH Terms
Shields Classification
Key Concepts5
In a population-based cross-sectional study of 464 subjects, iridolenticular contact area (ILCA), measured using swept-source optical coherence tomography (SSOCT) in the dark, was significantly associated with anterior chamber width (β=1.03, p=0.003), pupillary diameter (β=-1.9, p<0.001), and iris curvature (β=-17.35, p<0.001) in multivariable linear regression analysis.
In a population-based cross-sectional study of 464 subjects, iridolenticular contact area (ILCA) was smaller in eyes with gonioscopic angle closure (GAC) compared with those with open angles (4.28 ± 1.6 mm2 vs 6.02 ± 2.71 mm2, p<0.001).
In a population-based cross-sectional study of 464 subjects, iridolenticular contact area (ILCA) was independently associated with gonioscopic angle closure (GAC) (β=-0.03, p<0.001), iridotrabecular contact index (β=-6.82, p<0.001), or angle opening distance (β=0.02, p<0.001) after adjusting for covariates, and had an acceptable diagnostic performance for detecting GAC (AUC=0.69).
In a population-based cross-sectional study of 464 subjects, the mean age was 62 ± 6.6 years, with a majority being female (65.5%).
In a population-based cross-sectional study of 464 subjects, 143/464 subjects (28.6%) had gonioscopic angle closure (GAC), defined as non-visibility of the posterior trabecular meshwork in two or more angle quadrants.
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