Evaluation of focal defects in the nerve fiber layer using optical coherence tomography

Purpose: To analyze glaucomatous eyes with known focal defects of the nerve fiber layer (NFL) in cross-sectional and longitudinal studies, where OCT findings were correlated to clinical exam, NFL & stereo optic nerve head photography, and Humphrey 24-2 visual fields. Methods: The study group had 13 patients with focal defects of their NFL, 6 of whom were followed for 5 to 18 months with multiple OCT and full clinical evaluations, and seven with a one time evaluation. The mean age was 63.2 years. The control group had 13 patients with normal ocular exams, 3 of whom were followed with multiple OCT and clinical evaluations, and 10 with a one time full evaluation. Mean age was 64.2 years. Cross sectional imaging with OCT was performed circumferentially around the optic nerve head with a circle diameter of 3.37mm using an internal fixation technique. Results: OCT tomographs revealed significant areas of NFL defects in areas closely corresponding to NFL defects visible on clinical examination and red free photographs and corresponding to defects on the Humphrey visual fields. Conclusion: The longitudinal analysis of NFL thickness in eyes with focal defects showed good structural & functional correlation with clinical parameters over time. OCT has the potential as a clinical tool to detect changes in the NFL thickness, and thus to provide a quantitative manner in which to detect glaucoma and its progression, compared to clinical and visual field exams alone.