Abstract
Purpose: :
In advanced glaucoma, visual field defects are often dense, involve the central 10°. Assessment of retinal sensitivity by various visual field techniques; Humphrey 10-2 Full Threshold (H10) and SLO-Microperimetry (SLO-MP) within areas of RNFL defects by SLO-Optical Coherence Tomography (SLO-OCT) permits correlation of functional damage to anatomical loss, thus facilitating early detection of progression in advanced glaucoma. The purpose of this investigation was to correlate changes in visual fields (H10, SLO-MP) to changes in macular RNFL thickness (SLO-OCT) in advanced glaucoma at 3-years follow-up.
Methods: :
18 eyes of 12 patients with advanced glaucoma enrolled in a pilot study in 2008 were re-recruited for this prospective, cohort study. At 3-year follow-up, a modified 10-2 SLO-MP (OPKO/OTI Instrumentation Inc.) was performed within 3-months of the last reliable H10 (Zeiss Medetec) using a Goldman size III 200 msec stimulus presented at 1-second interval with real time monitoring of fixation. A standard CSME grid (diameter=3.5 mm) was used to divide the baseline macular RNFL (SLO-OCT, 2008) into 3 ring segments. Primary outcome was correlation of retinal sensitivity measured as the mean dB attenuation level (H10 and SLO-MP) at 3-years to mean baseline macular RNFL thickness (SLO-OCT) within the corresponding ring section of the CSME grid. Secondary outcome was decline in mean retinal sensitivities (dB) of SLO-MP and H10 at 3-years. Linear regression and ANOVA was used for analysis.
Results: :
At 3-years, mean macular RNFL thickness (SLO-OCT) recorded at baseline did not correlate with the H10 or SLO-MP thresholds in ring 1. However, in ring 2, the 2008 RNFL thickness significantly correlated with both H10 (p=0.0477) and SLO-MP (p= 0.0452). In Ring 3 the 2008 RNFL thickness was significantly correlated with both H10 (p=0.0255) and SLO-MP (p=0.0320). There was a comparable reduction in retinal sensitivity in both SLO-MP (Rings 1, 2 and 3 = p < 0.0001) and H10 (Ring 1: p=0.0116, ring 2: p=0.0027 and ring 3: p=0.0064) at 3-years.
Conclusions: :
Macular RNFL thickness measured by SLO-OCT is a good predictor of 3-year reduction of retinal sensitivity by H10 and SLO-MP with a trend towards better correlation with SLO-MP.
Keywords: visual fields • clinical laboratory testing • aging: visual performance