Sensitivity of Imaging the Peripheral Nerve Fibre Layer using a Confocal Scanning laser Ophthalmoscope to Detect Glaucoma

Purpose: The aim of this study was to evaluate the sensitivity to detect glaucoma by observer-dependent nerve fibre layer imaging and evaluation using a scanning laser ophthalmoscope. Patients and Methods: Fifty-four patients with primary open angle glaucoma (POAG), 41 patients with normal tension glaucoma (NTG) and 65 eyes of control subjects were included in a retrospective study. Nerve fibre layer imaging was performed using a confocal scanning laser ophthalmoscope (SLO, Rodenstock Instr., argon laser 488 nm). Digitised images of the nerve fibre layer were graded off-line by two masked experienced observers. The nerve fibre layer was graded for every single degree (defect or no defect) at 1.7 and 3.4mm distance to the optic nerve head omitting the nasal 110 degrees. Sensitivity and specificity levels were calculated using ROC analysis. Results: Patients with POAG exhibited nerve fibre layer defects of 100 degrees +/- 94 degrees (1.7 mm and 3.4 mm distance) and patients with NTG of 94 +/- 94 (1.7mm distance) and 103 +/- 92 (3.4mm distance), significantly larger compared to controls (1 +/- 3 [1.7mm, p < 0.0001] and 1 +/- 4 [3.4mm, p < 0.0001]). Sensitivity at > 90% specificity was 80% (1.7mm) and 82% (3.4mm) for POAG. In NTG, sensitivity at > 90% specifity was 81% (1.7mm) and 85% (3.4 mm). In early glaucoma (MD < -6 dB, n = 39) sensitivity decreased to 75% (1.7mm) and 81% (3.4 mm). Conclusion: Observer-dependent evaluation and grading of the nerve fibre layer using a scanning laser ophthalmoscope reaches considerably high sensitivity levels to detect glaucoma with negligible differences between the central and peripheral regions.