Positional and Curvature Difference of Lamina Cribrosa According to the Baseline Intraocular Pressure in Primary Open-Angle Glaucoma: A Swept-Source Optical Coherence Tomography (SS-OCT) Study

Purpose To investigate the variation of lamina cribrosa (LC) structure based on the baseline intraocular pressure (IOP) in eyes with primary open-angle glaucoma (POAG) and healthy individuals using swept-source optical coherence tomography. Methods A total of 108 eyes with POAG and 61 healthy eyes were recruited. Based on the baseline IOP, the POAG eyes were divided into higher-baseline IOP (HTG; baseline IOP > 21 mmHg, n = 38 eyes) and lower-baseline IOP (NTG; baseline IOP <= 21 mmHg, n = 70 eyes). The anterior laminar insertion depth (ALID), mean LC depth (mLCD), and the LC curvature index (mLCD-ALID) were measured, and compared among the three groups. The regional variation of LC structure was evaluated by vertical-horizontal ALID difference. Results The mLCD and LC curvature index were greatest in HTG eyes (520.3 +/- 123.0 and 80.9 +/- 30.7 mu m), followed by NTG (463.2 +/- 110.5 and 64.5 +/- 30.7 mu m) and healthy eyes (382.9 +/- 107.6 and 47.6 +/- 25.7 mu m, all P < 0.001). However, there were no significant difference in ALID between HTG and NTG eyes. The vertical-horizontal ALID difference was larger in NTG eyes (72.8 +/- 56.2 mu m) than in HTG (32.7 +/- 61.4 mu m, P = 0.004) and healthy eyes (25.5 +/- 34.8 mu m, P < 0.001). Conclusions Lamina cribrosa position and curvature differed in POAG eyes with low and high IOP. This would support the theory that IOP induced biomechanical effects on the optic play a role on glaucoma.