Abstract
Abstract: :
Purpose:To determine the performance of optical coherence tomography for evaluating clinical asymmetry of optic discs. Methods:Thirty–nine glaucoma suspects or patients with early OAG who had disc asymmetry on stereoscopic disc photographs were identified. Inclusion criteria were visual acuity 20/40 or better, anisometropia < 2D, and age ≥ 30 years in the absence of other ocular or neurologic disease. Two clinicians reviewed the disc photos and identified the eye with the larger cup–to–disc (c/d) ratio and graded all discs as normal, indeterminate or probable glaucoma. Asymmetry of NFLT clock hour sectors, which are defined against a normal database by the STRATUS OCT3, and differences in the average nerve fiber layer thickness (NFLT) were compared to clinician grading. Results: Clinicians and OCT agreed upon disc asymmetry in 23 patients (59%). They disagreed in 10 patients (26%). For 6 patients (15%) no asymmetry was detected by OCT. Correlation of c/d asymmetry (mean 0.18 ± 0.097) with average NFLT asymmetry (mean 10.92 ± 10.23 microns) showed a Pearson coefficient of –0.64 (p < 0.01). Ten patients with disc asymmetry graded as normal in one eye vs. indeterminate in the other eye and 10 patients with normal discs in one eye vs. probable glaucoma in the other eye were detected. The mean NFLT difference was statistically significant between the indeterminate and probable glaucoma groups (6.27 ± 3.5 µm vs. 16.9 ± 11 µm, p = 0.019). Conclusions:OCT NFL measurements disagreed upon disc asymmetry in a large proportion of cases identified as asymmetric by experienced clinicians. Further evaluation is required to determine the clinical utility of NFL measurements of asymmetry between eyes.
Keywords: optic disc • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)