Correlation of frequency-doubling perimetry with retinal nerve fiber layer thickness and optic disc size in ocular hypertensives and glaucoma suspects

Abstract

Purpose: To determine the structure-function correlation using frequency-doubling technology (FDT) perimetry and optical coherence tomography (OCT) in glaucoma suspects, and analyze their relationship to optic disc size.

Methods: Sixty eyes of 60 ocular hypertensive patients (OHT) and 54 eyes of 54 subjects with optic disc features suspicious of glaucoma (disc suspects) with normal visual fields on Standard Achromatic Perimetry were recruited. All subjects underwent FDT perimetry using the N-30 program, and the mean deviation (FDT-MD) and FDT-pattern SD were computed. Average and inferior retinal nerve fiber layer (RNFL) thickness and disc area were measured on Stratus OCT. Pearson correlation coefficient was calculated among all the measurements.

Results: In disc suspects, FDT-MD correlated significantly with RNFL thickness measurements (P<0.001; P=0.003) and disc area (P<0.001). There was no correlation with the vertical cup-disc area ratio (VCDR) and FDT indices. In OHT, FDT-MD correlated significantly with average RNFL thickness (P=0.038), and there was a significant negative correlation between FDT-MD and the VCDR (0.042). The FDT-pattern SD negatively correlated with RNFL thickness measurements (P=0.008; P=0.03). The disc area correlated significantly with the average and inferior average RNFL thickness measurements in both groups of patients (P=0.029 and P=0.007; P=0.013 and P=0.013, respectively).

Conclusions: In OHT, optic discs with larger VCDR and thinner RNFL had lower FDT-MD values. In disc suspects, smaller-sized discs had thinner RNFL and lower values of FDT-MD. FDT perimetry and OCT seem to be useful adjuncts to detect these eyes, which might warrant close follow-up to eventually detect glaucoma by Standard Achromatic Perimetry.