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

Objective: To analyze glaucomatous eyes with known focal defects of the ner ve fiber layer (NFL), relating optical coherence tomography (OCT) findings to clinical examination, NFL and stereoscopic optic nerve head (ONH) photog raphy, and Humphrey 24-2 visual fields. Design: Cross-sectional prevalence study. Participants: The authors followed 19 patients in the study group and 14 pa tients in the control group. Intervention: Imaging with OCT was performed circumferentially around the O NH with a circle diameter of 3.4 mm using an internal fixation technique, O ne hundred OCT scan points taken within 2.5 seconds were analyzed. Main Outcome Measures: Measurements of NFL thickness using OCT were perform ed. Results: In most eyes with focal NFL defects, OCTs showed significant thinn ing of the NFL in areas closely corresponding to focal defects visible on c linical examination, to red-free photographs, and to defects on the Humphre y visual fields. Optical coherence tomography enabled the detection of foca l defects in the NFL with a sensitivity of 65% and a specificity of 81%, Conclusions Analysis of NFL thickness in eyes with focal defects showed goo d structural and functional correlation with clinical parameters, Optical c oherence tomography contributes to the identification of focal defects in t he NFL that occur in early stages of glaucoma.