Comparative Study of Lamina Cribrosa Thickness Between Primary Angle-Closure and Primary Open-Angle Glaucoma

Abstract

Purpose: To compare lamina cribrosa thickness (LCT) of primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG) using the enhanced depth-imaging mode of the Heidelberg Spectralis spectral-domain optical coherence tomography (EDI-OCT). Patients and Methods: A comparative cross-sectional study was conducted. We enrolled 34 patients with PACG, 38 with POAG, and 62 controls, testing only one eye of each participant. Lamina cribrosa thickness was determined at the center of the optic nerve head using EDI-OCT. Nine points of LCT were measured, and LCT averages were analyzed. Results: Mean age, number of glaucoma medications, current intraocular pressure (IOP), cup to disc ratio, and visual field indices, were not significantly different between PACG and POAG eyes. The maximum IOP (SD) was higher in PACG than in POAG, at 32.5 (10.46) vs 25.05 (6.42) mmHg (p = 0.001), and LCTs were significantly different among the PACG, POAG and control groups. Mean (SD) LCTs were 226.99 (31.08), 257.17 (19.46), and 290.75 (28.02) mu m, respectively (p < 0.001). Lamina cribrosa thickness was correlated with mean deviation of the visual field (p = 0.001; correlation coefficient, rs = 0.347), while it was inversely correlated with maximum IOP (p < 0.001; correlation coefficient, rs = -0.592). Linear regression analysis revealed that LCT was inversely related to age (p = 0.008), female (p = 0.018), and maximum IOP (p = 0.002). LCT was marginally related to visual field MD (p = 0.053). Conclusion: Glaucomatous eyes had thinner LCT than controls, and maximum IOP was inversely correlated to the LCT. PACG eyes had higher maximum IOP and thinner LCT than POAG ones. In living eye, EDI-OCT emphasizes the pressure-dependent mechanism of glaucoma on lamina cribrosa deformation and the higher IOP-loaded stress which leads to a greater lamina cribrosa strain.