A new parameter for assessing the thickness of the retinal nerve fiber layer for glaucoma diagnosis

Purpose. To investigate a new method for assessing the thickness of the retinal nerve fiber layer thickness (NFLT) for glaucoma diagnosis, using scanning laser polarimetry. Material and Methods. Thirty eyes of thirty patients with ocular hypertension or glaucoma were examined using a scanning laser polarimeter. NFLT was measured in each of four 90-degree quadrants; superior(S), temporal (T), inferior (I) and nasal (N) along 1.5-disc diameters concentric from the disc margin. The new parameters S-N (meaning the thickness of the superior nerve fiber layer over the nasal one) etc. were compared with the conventional parameters (S, SIN, etc.). The correlations between these parameters and the mean threshold of the associated visual field test points were included in the comparison. Results. The total thickness (sum of S, I, N and T), N and T did not correlate to the visual field, but S and I did. The new parameters were well correlated to the visual field, S-N giving the best correlation coefficient (rs = 0.782, p < 0.0001), and sensitivity and specificity (the area under the receiver operating characteristic curves was 0.91). Conclusions. The nasal NFLT was the smallest part of individual variation and glaucomatous damage. The new parameters, based on the nasal NFLT, were good evaluators of the changes in glaucoma.