Retinal Nerve Fiber Layer Damage as Assessed by Optical Coherence Tomography in Eyes With Visual Field Defect Detected by Frequency Doubling Technology Perimetry but Not by Standard Automated Perimetry in the Diagnostic Innovations in Glaucoma Study (DIGS)

Abstract

Purpose: : To determine whether the visual field loss detected by frequency doubling technology perimetry (FDT) but not by standard automated perimetry (SAP) is associated with retinal nerve fiber layer damage measured using optical coherence tomography (OCT).

Methods: : Subjects were recruited from the longitudinal University of California, San Diego, Diagnostic Innovations in Glaucoma Study and included 93 subjects who had 2 or more reliable SAP–SITA and FDT 24–2, and at least 1 Stratus OCT test all conducted within a 6–month time window. Subjects were divided into 4 groups based on the SAP and FDT result. 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 were compared between groups.

Results: : The average thickness, and inferior and superior quadrant thickness of the subjects with normal SAP and abnormal FDT was about 8 to10% lower than those of the subjects with normal SAP and normal FDT. In addition, compared to those with normal SAP and normal FDT, a significantly higher proportion of subjects with normal SAP and abnormal FDT had OCT–measured RNFL thickness outside of 95% limits in the inferior and superior quadrants (P=0.0478) and outside 99% limits in the inferior quadrant (P=0.0098).

Conclusions: : When SAP is within the normal range, visual field loss detected by FDT is associated with glaucomatous RNFL damage. This result supports the validity of FDT and OCT as tools to detect early glaucoma.

Keywords: perimetry • nerve fiber layer