Contrast Sensitivity by M&S Smart System II and Visual field Parameters in Patients with Primary Open-Angle Glaucoma

Abstract

 

Purpose

 

Loss of contrast sensitivity (CS) may occur early in glaucoma, and precede clinically detectable changes in visual acuity (VA) and visual field (VF). CS testing by a computerized vision-testing device (M&S Smart System II) has been validated against thea gold standard Pelli-Robson CS testing. We determined relationships between CS by the M&S Smart System II and routine visual functional measures in patients with glaucoma.

 

Methods

 

We recruited patients with primary open-angle glaucoma (POAG) without other eye conditions. Each patient underwent 1) VA and CS testing in a standardized manner using a calibrated M&S Smart System II; and 2) VF testing (Humphrey SITA 24-2). Inclusion criteria included VA > 20/40 and reliable VF testing (fixation losses, false positives and false negatives < 33%). Spearman rank correlations were used to determine relationships within CS, VA, and VF parameters including mean deviation (MD), pattern standard deviation (PSD), and visual field index (VFI). Only the better eye was recruited for analysis based on MD. Based on the Bonferroni correction for multiple comparisons, correlations were considered statistically significant if p-value < 0.005 (two-tailed).

 

Results

 

A total of 108 eyes of 108 patients met the inclusion criteria and were included for analysis. The mean age of the patients included was 65.81±12.74 years old. The mean BCVA was 20/25 (logMAR: 0.09±0.10) and the mean CS was 1.37±0.16. The spearman rank correlation coefficients are shown in Table 1. Amongst the VF parameters, VA correlated most strongly with MD. CS correlated most strongly with MD and VFI.<br /> TABLE 1: Correlations between Contrast Sensitivity Testing and Visual Functional Measures

 

Conclusions

 

When compared to VA, CS correlates to a greater degree with all three VF parameters. Our results suggest that CS can serve as a surrogate for VF measures, supporting routine use of CS testing. Given that CS testing by the M&S System can be done quickly, incorporation into a budy clinical practice is practical. Patients with POAG often experience decreased vision without discernable changes in their VA. Since VF testing is not routinely performed at each visit, CS testing could be used more frequently to monitor subjective deterioration in quality of vision in patients with POAG. The strong correlations between CS, MD and VFI drive home these conclusions.