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. NFL T 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, S/N, 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 = O. 782, p < O.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.