Measurement of Structural Parameters of the Lamina Cribrosa in Primary Open-Angle Glaucoma and Chronic Primary Angle-Closure Glaucoma by Optical Coherence Tomography and Its Correlations with Ocular Parameters

Purpose: To measure lamina cribrosa thickness (LCT) and anterior lamina cribrosa surface depth (ALCSD) in primary open-angle glaucoma (POAG), chronic primary angle-closure glaucoma (CPACG), and control patients using spectral-domain optical coherence tomography (SD-OCT) and examine its association with relevant ocular parameters. Methods: In this cross-sectional study, 61 healthy volunteers (61 eyes), 65 POAG patients (65 eyes), and 55 CPACG patients (55 eyes) were recruited to obtain radial B-scans of the optic nerve head by way of enhanced depth imaging using Heidelberg SD-OCT. The obtained LCT and ALCSD were compared among the control, POAG, and CPACG groups. In addition, we evaluated the relationships of mean lamina cribrosa (LC) parameters with visual field (VF) mean deviation (MD), retinal nerve fiber layer (RNFL) thickness, intraocular pressure (IOP), and axial length. Results: The mean LCT of CPACG eyes was greater than that of POAG eyes (p = 0.003), but less than that of normal eyes (p < 0.001). The mean ALCSD of POAG and CPACG eyes was greater than that of normal control eyes (both p < 0.001). However, the mean ALCSD showed no significant difference between the POAG and CPACG groups (p = 0.073). Among all eyes, lower MD and thinner RNFL thickness were associated with a deeper and thinner LC (all p < 0.001). Conclusion: LCT is thinner in POAG compared to CPACG eyes. This is compatible with less deformation and compression of the LC in CPACG eyes, implying that the mechanisms of glaucomatous damage are different between POAG and CPACG eyes. Furthermore, VF MD and RNFL thickness were related to LCT and ALCSD in all patients.