Characteristics and variability of iridocorneal angle: an anterior segment optical coherence tomography study

Abstract

AbstractPurposeWe aimed to assess the iridocorneal angle by Anterior Segment Optical Coherence Tomography (AS‐OCT) and to identify relations between angle measurements and subject factors in a healthy Caucasian Tunisian population.MethodsA prospective cross‐sectional study was performed in 201 right eyes of 201 healthy subjects.All patients underwent a complete ophthalmic examination, automated refraction, ultrasound biometry and AS‐OCT examination at the same day. The iridocorneal angle measurements including trabecular iris angle (TIA), angle opening distance 500 (AOD500) and trabecular iris space area 500 (TISA500) were manually measured using AS‐OCT. Correlations and associations were examined between angle measurements and demographic, clinical and ocular factors.ResultsThe means recorded were TIA = 34.6 ± 11.4 degrees, AOD500 = 515 ± 260.7 µm and TISA = 500 0.178 ± 0.091 mm². We found that 90.3% of the iridocorneal angles were open.Correlations were detected between angle means and age (R = −0.414; p < 0.01), intraocular pressure (R = −0.145; p < 0.01), spherical error (R = −0.410; p < 0.01), anterior chamber depth (R = 0.734; p < 0.01), axial length (R = 0.489; p < 0.01) and lens thickness (R = −0.519; p < 0.01).No relation was observed with sex (p = 0.084).ConclusionsAS‐OCT is a non‐invasive tool to identify subjects at risk of angle closure. In this Caucasian population, 90.3 % of the iridocorneal angles were open. AOD 500 and TISA 500 were as reliable as TIA in iridocorneal angle assessment. The angle width was correlated with demographic and ocular factors. Among the main limitations, was the fact that we did not measure the lens vault despite the known contribution of this factor to angle width variation.