Nerve fiber layer measurements with scanning laser polarimetry in ocular hypertension

To measure and compare scanning laser polarimeter measurements of the nerve fiber layer in normal subjects and in patients with ocular hypertension (OHT).

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 65536 individual retinal locations (256 x 256 pixels). Retardation measurements within a 10-pixel-wide band located concentrically with the disc margin at 1.7-disc diameters were evaluated.

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 degrees sectors around the disc were significantly higher in normal subjects than in patients with OHT.

Retardation measurements with the scanning laser polarimeter were significantly lower in patients with OHT than in normal subjects.