PURPOSE: To describe nonglaucomatous retinal nerve fiber layer (RNFL) defects in patients with Behcet uveitis. DESIGN: Cross-sectional study and observational case series. METHODS: We reviewed the clinical photographs of patients with Behcet uveitis (n = 259), ocular toxoplasmosis (n = 120), and multiple sclerosis (MS)-associated uveitis (n = 40) for the presence of localized RNFL defects. Behcet patients with localized RNFL defects were invited to participate in a prospective evaluation including standard automated perimetry, spectraldomain optical coherence tomography (SD OCT), and RNFL thickness analysis. Main outcome measures were the prevalence of localized RNFL defects, perimetric and SD OCT findings, and RNFL thickness analysis. RESULTS: Sixty-two patients with Behcet uveitis (24%) had localized RNFL defect(s) without any visible scar. Twenty patients (17%) with ocular toxoplasmosis had a localized RNFL defect associated with a retinochoroidal scar in all. None of the MS patients had a localized RNFL defect. Of the 19 patients (24 eyes) with RNFL defect associated with Behcet uveitis who returned for follow-up, there was a corollary thinning on SD OCT B-scan in all and a corresponding visual field defect in 83%. RNFL thickness analysis was within normal limits in 54%, but revealed thinning in the thickness profile scale in 46% and in the pie chart in 21%. CONCLUSION: In Behcet uveitis, localized RNFL defects may be caused by microvascular ischemia at the optic nerve head and/or at the posterior pole and may serve as a helpful ocular diagnostic clue and an indicator of posterior pole involvement, a risk factor for poor visual prognosis. [ABSTRACT FROM AUTHOR]