Usefulness of optical coherence tomography parameters of the optic disc and the retinal nerve fiber layer to differentiate glaucomatous, ocular hypertensive, and normal eyes

Abstract

Purpose: To assess Stratus optical coherence tomography (OCT) original parameters for identifying glaucomatous damage and to evaluate differences among glaucomatous, ocular hypertensive, and normal eyes.

Design: Cross-sectional prospective study.

Subjects and methods: The study was conducted at 2 centers. The study population consisted of 55 normal individuals, 95 patients with ocular hypertension (OHT), and 79 patients with glaucoma. Retinal nerve fiber layer (RNFL) and optic nerve head OCT protocols were used to evaluate all study participants. Measurements taken were RNFL thickness, several ratios, RNFL asymmetry between both eyes, rim volume, rim width, disc area, cup area, rim area, cup/disc (C/D) area ratio, and horizontal and vertical C/D ratios. The main outcome measures were the differences in OCT parameters among groups and the areas under the receiver operating characteristic curves (AROC).

Results: Mean RNFL thickness around the disc, and superior and inferior RNFL thickness, were significantly thinner in glaucomatous eyes than in OHT or normal eyes (P<0.001). Rim parameters were significantly smaller in glaucomatous eyes than in normal (P<0.001) and OHT eyes (P=0.01). C/D ratios were significantly greater in glaucomatous eyes than in OHT (P<0.001) and normal (P<0.001) eyes. Significant differences were found between normal and OHT eyes in 7 disc parameters. No difference was found among groups in parameters describing RNFL asymmetry between both eyes. The AROC curves of the other RNFL and disk parameters ranged from 0.741 to 0.85.

Conclusions: Almost all RNFL and disc parameters showed significant differences and discriminated between glaucomatous and normal eyes. There were significant differences in some optic nerve parameters, but no RNFL parameters, between normal and OHT eyes.