Optic Nerve Head Characteristics in Chronic Angle Closure Glaucoma Detected by Swept-Source OCT.

Purpose: To compare structural features in prelaminar and laminar tissues of the optic nerve head (ONH) in chronic angle closure glaucoma (CACG), primary open angle glaucoma (POAG), and control subjects.Materials and Methods: ONH imaging was performed using swept-source optical coherence tomography (SS-OCT) for measurements of minimum rim width at Bruch's membrane opening (BMO-MRW), horizontal, and vertical lamina cribrosa depth (LCD). Prelaminar defects, categorized as hole and wedge, and lamina cribrosa (LC) defects were identified. Enhanced depth imaging spectral domain OCT (EDI-OCT) customized to perform high-resolution volume scans was used in conjunction to further characterize prelaminar holes. One eye per subject was analyzed.Results: Eighty subjects (20 CACG, 40 POAG, and 20 controls) were included in the study. CACG and POAG groups had similar mean deviation on Humphrey visual field testing (-6.9 5.1 vs. -6.3 +/- 6.0 dB, p > 0.05) and IOP on the day of imaging (14.0 +/- 3.1 vs. 13.8 +/- 2.7 mmHg, p > 0.05). Thinnest and global BMO-MRW in CACG (120.3 +/- 44.8, 225.5 +/- 53.9 m) and POAG (109.7 +/- 56.3, 213.8 +/- 59.7 m) groups were lower than controls (200.1 +/- 40.8, 308.3 +/- 70.8 m; p < 0.001 for both). Prelaminar holes were most frequent in CACG (65.0%) than POAG (25.0%, p=0.008) or control groups (20.0%, p=0.01). After adjusting for demographic and ophthalmic covariates, CACG was associated with increased odds of having prelaminar holes compared to POAG (odds ratio, 9.79; 95% CI, 2.12-45.19; p=0.003). Hole volume was similar between CACG and POAG (p > 0.05), but the CACG group had more holes per scan than POAG (maximum 2.5 +/- 1.9 vs. 1.2 +/- 0.4, p=0.02). Prelaminar wedge defects were less common in the CACG than the POAG group (5.0% vs. 37.5%, p=0.02). The CACG group did not differ from controls in laminar characteristics, such as LCD and LC defects.Conclusions: SS-OCT evaluation of the ONH revealed more frequent prelaminar holes in CACG compared to POAG and control patients.