Measurement by nerve fiber analyzer of retinal nerve fiber layer thickness in normal subjects and patients with ocular hypertension

PURPOSE: To measure retinal nerve fiber layer (NFL) thickness in normal subjects and patients with ocular hypertension and examine the relationship between age and normal NFL thickness. METHODS: Nerve fiber layer thickness was determined by scanning laser polarimetry in 210 normal subjects and 100 patients with ocular hypertension, Relative ratios for the superior and inferior NFLs were calculated by dividing the NFL values of the respective regions by the nasal value. RESULTS: Mean superior NFL in normal subjects measured 2.5 (95% confidence interval [CI], 1.3 to 3.7), and mean inferior NFL, 2.4 (95% CI, 1.2 to 3.6), Regression analysis showed a gradual decrease in NFL thickness with increasing age, In the patients with ocular hypertension, mean superior and inferior NFL were significantly lower compared with those of normal subjects: superior, 1.6 (95% CI, 0.4 to 2.8) and inferior, 1.6 (95% CI, 1.0 to 2.2). Of the patients with ocular hypertension, 58 of 100 (58%) had an abnormal NFL parameter. CONCLUSIONS: Normograms we obtained for NFL as determined by scanning laser polarimetry may serve as reference points for future studies. Patients with ocular hypertension had a significantly lower NFL thickness, although there was some overlap in resulting measurements with those of normal subjects. The Nerve Fiber Analyzer may be useful for individual follow-up of people at risk for glaucoma; however, its role as a screening instrument requires further study.