Nerve Fiber Layer Measurements With Scanning Laser Polarimetry in Ocular Hypertension

Abstract

Objective: To measure and compare scanning laser polarimeter measurements of the nerve fiber layer in normal subjects and in patients with ocular hypertension (OHT). Methods: Scanning laser polarimetry was performed in 39 normal subjects and 39 age-matched patients with OHT. One eye of each patient was randomly selected for the study. For each eye, a mean retardation map was calculated from 3 separate scans of 65 536 individual retinal locations (256×256 pixels). Retardation measurements within a 10-pixel-wide band located concentrically with the disc margin at 1.7-disc diameters were evaluated. Results: Mean(±SD) retardation (in degrees) was significantly higher (P=.03) in normal subjects (10.4±1.5 degrees) than in patients with OHT (9.7±1.0 degrees). In the inferior retina, mean±SD retardation was higher (P=.03) in normal subjects (10.8±1.7 degrees) than in patients with OHT (10.1±1.0 degrees). In the superior retina, mean±SD retardation also was higher in normal subjects (9.8±1.6 degrees) than in patients with OHT (9.3±1.2 degrees), although the difference was not statistically significant (P=.19). Retardation measurements for 3 of eight 45° sectors around the disc were significantly higher in normal subjects than in patients with OHT. Conclusion: Retardation measurements with the scanning laser polarimeter were significantly lower in patients with OHT than in normal subjects.