Effects of Trabecular Meshwork Width and Schlemm's Canal Area on Intraocular Pressure Reduction in Glaucoma Patients.

PURPOSE To evaluate the effects of baseline trabecular meshwork (TM) and Schlemm's canal (SC) microstructures on intraocular pressure (IOP) reduction amount in treatment-naive patients with primary open-angle glaucoma (POAG). METHODS A total 69 eyes of POAG patients who had not been treated with IOP-lowering agent were enrolled in this retrospective study. The patients had been prescribed topical IOP-lowering agent and used it for 1 year. The morphologic features of the TM and SC were collected using anterior segment module of spectral-domain optical coherence tomography with enhanced depth imaging at baseline. Images of the nasal and temporal corneoscleral limbus were obtained with serial horizontal enhanced depth imaging B-scans and TM width and SC area were measured in each scan. We investigated the effects of baseline TM and SC microstructures on IOP reduction amount. RESULTS The baseline IOP of 69 glaucomatous eyes was 17.9 ± 3.8 mmHg, and the mean amount of IOP reduction was 3.5 ± 2.1 mmHg after 1 year. Mean TM widths of nasal and temporal sector were 470.33 ± 80.05 and 479.74 ± 79.59 μm, respectively. SC area was measured as 4,818.50 ± 1,464.28, 4,604.23 ± 1,567.73 μm2 at nasal sector and temporal sector, respectively. The correlation analysis revealed a positive correlation between SC area and average amount of IOP reduction, indicating that the larger baseline SC area, the greater the IOP drop with topical IOP-lowering agents. However, no correlation was found between TM width and IOP lowering amount in patients with POAG. CONCLUSIONS The baseline SC area showed positive correlation with the IOP reduction amount in patients with POAG. This finding suggests that the SC area can be a clinical parameter to predict the IOP reduction amount before using IOP-lowering agents in POAG patient.