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 mm2 vs 6.02±2.71 mm2, 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.
- Anterior chamber
- Lens and zonules
Data availability statement
Data are available on reasonable request.
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Contributors Design of study (TAT, MEN, JHMQ, CYC and TA); Conduct of the study (TAT, MEN, XW and MT); Collection and management of data (TAT, XW, BYX, H-BL and TA); Analysis and Interpretation of data (TAT, MEN, XW, BYX, CYC and TA); Preparation of manuscript (TAT, MEN, XW, BYX, H-BL and TA); Review or approval of manuscript (MT, JHMQ, H-BL, CYC and TA). TA is the guarantor of the manuscript.
Funding The study was supported by the National Medical Research Council (TA; NMRC/STAR/0023/2014 and MOH-000435) and the National Natural Science Foundation of China (XW; 12002025).
Disclaimer The sponsor or funding organisation had no role in the design or conduct of this research. The views expressed are those of the author(s) and not necessarily those of the NMRC, Singapore.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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