Despite near-normal visual acuity (VA), almost all patients with advanced glaucomatous visual field (VF) damage have moderate to profound deficits in contrast sensitivity, according to a new study.

This cross-sectional study evaluated 28 patients with open-angle glaucoma, VAs better than 20/40 and VF mean deviations worse than -15dB. Patients underwent VA, VF and contrast sensitivity testing with the Pelli-Robson (PR) chart and the Freiburg Visual Acuity and Contrast Test (FrACT). Retest measurements were obtained within one month.

The team observed median contrast sensitivities of 1.35 log units with the PR chart and 1.39 log units with the FrACT. They noted that VA explained less than 40% of the variance in contrast sensitivity. They also discovered that contrast sensitivity estimates of both tests were closely related, but sensitivity values were 0.09 log units higher with the FrACT compared with the PR chart, and the 95% repeatability intervals were 46% tighter with the PR chart.