Retinal Nerve Fiber Layer Damage as Assessed by Optical Coherence Tomography in Eyes with a Visual Field Defect Detected by Frequency Doubling Technology Perimetry but Not by Standard Automated Perimetry

Abstract

To determine whether the visual field (VF) loss detected by frequency doubling technology perimetry (FDT) but not by standard automated perimetry (SAP) is associated with retinal nerve fiber layer (RNFL) damage measured using optical coherence tomography (OCT). Observational case-control study. Ninety-three subjects were recruited from the longitudinal University of California, San Diego, Diagnostic Innovations in Glaucoma Study. All participants had > or =2 reliable SAP-Swedish Interactive Testing Algorithm and FDT 24-2 tests and at least one Stratus OCT test, all conducted within a 6-month time window. Retinal nerve fiber layer thickness measured with OCT and the number of sectors with OCT-measured RNFL thickness lower than the 95% confidence interval (CI) or 99% CI based on the instrument's normative database. Compared with those with normal SAP and FDT results, a significantly higher proportion of subjects with normal SAP and abnormal FDT results had OCT-measured RNFL thickness outside 95% limits in the inferior and superior quadrants (P = 0.048) and outside 99% limits in the inferior quadrant (P = 0.010). When SAP is within normal range, some patients with VF loss detected by FDT show a decreased RNFL thickness, possibly indicating the presence of glaucomatous damage. These results support the validity of FDT as a tool to detect early glaucoma.