QUANTIFICATION OF NERVE-FIBER LAYER THICKNESS IN NORMAL AND GLAUCOMATOUS EYES USING OPTICAL COHERENCE TOMOGRAPHY - A PILOT-STUDY

Purpose: Quantitative assessment of nerve fiber layer (NFL) thickness in normal and glaucomatous eyes, and correlation with conventional mea surements of the optic nerve structure and function. Methods: We studi ed 59 eyes of 33 subjects by conventional ophthalmologic physical exam ination, Humphrey 24-2 visual fields, stereoscopic optic nerve head ph otography, and optical coherence tomography. Results: Nerve fiber laye r thickness as measured by optical coherence tomography demonstrated a high degree of correlation with functional status of the optic nerve, as measured by visual field examination (P=.0001). Neither cupping of the optic nerve nor neuroretinal rim area were as strongly associated with visual field loss as was NFL thickness (P=.17 and P=.21, respect ively). Cupping correlated with NFL thickness only when the cup was sm all (cup-to-diameter ratio, 0.1 to 0.3) or large (cup-to-diameter rati o, 0.8 to 1.0) (P=.006); there was no correlation between cupping and NFL thickness otherwise. Nerve fiber layer, especially in the inferior quadrant, was significantly thinner in glaucomatous eyes than in norm al eyes (P=.04). Finally, we found a decrease in NFL thickness with ag ing, even when controlling for factors associated with the diagnosis o f glaucoma (P=.03). Conclusions: Nerve fiber layer thickness can be me asured using optical coherence tomography. These measurements provide good structural and functional correlation with known parameters.