Evaluation of the lamina crivosa thickness and depth, the prelaminar nerve tissue thickness and the Bruch's membrane opening-based minimum rim width in eyes with and without primary open-angle glaucoma: an enhanced depth imaging OCT study of the optic nerve head and the correlation between anatomy and function
Abstract
Purpose
To evaluate the lamina crivosa (LC)thickness (LCT), depth (LCD), prelaminar thickness (PLTT) and Bruch's membrane opening-based minimum rim width (BMO-MRW) in primary open-angle glaucoma (POAG) and normal eyes (NE) and their correlation with function (MD).
Methods
This observational study included 45 eyes (25 eyes with POAG; 20 normal eyes),which were evaluated clinically, by applanation tonometry, pachymetry, Octopus perimetry and by enhanced depth imaging-optical coeherence tomography (EDI-OCT). A grid scan of the optic herve head (ONH), averaged 80 scans, to image the LCT, LCD and PLTT in center, mid-inferior (I-ONH), and superior positions and a nerve fiber layer (NFL) scan were done. LCT was the distance between borders of the LC. LCD was the distance between BMO reference line-anterior LC border. BMO-MRW was the shortest distance between BMO and internal limiting membrane. All values were compared between both groups and correlations between variables were tested.
Results
Global LCT was lower in POAG (132.9 ± 40.1 µm) than in control group (235.9 ± 36.8 µm, p < 0.05). Mean LCD was higher in POAG (572.2 ± 195.2 µm). Mean PLTT was lower in POAG (91.9 ± 49.9 µm, p < 0.05), as occurred with BMOMRW. In all eyes, the global LCT was correlated to NFLT (R = 0.61) and BMOMRW (R = 0.67; p < 0.001). In POAG eyes, global NFL was correlated to BMOMRW (R = 0.67) and the PLTT (R = 0.386). In I-ONH scan, PLTT was correlated with LCD (R = −0.502) and inferior-temporal (IT)-NFLT(R = 0.479, p = 0.015). MD was correlated with PLTT(R = −0.597) and MBOMRW (R = −0.670, p < 0.01).
Conclusions
Glaucoma can cause a decrease in LCT, PLTT, BMOMRW and increase in LCD, being potential markers of glaucomatous damage. Some ONH-OCT parameters correlated with function, as measured by the MD. ONH EDI-OCT imaging with automatic segmentation would be useful in glaucoma evaluation.
