Abstract
Purpose: :
Precise, fundus-oriented methods to assess extent of central field loss are not widely available, whereas contrast sensitivity and letter acuity are comparatively simple and accessible measures of visual function. We evaluated the association between extent of central field loss, contrast sensitivity, and letter acuity.
Methods: :
Central field loss, Pelli-Robson contrast sensitivity and logMAR visual acuity were assessed monocularly in 40 eyes of subjects referred for comprehensive vision rehabilitation at an academic ophthalmology department. Extent of central field loss was evaluated using macular perimetry (OPKO Instrumentation), which is not dependent on stable or central fixation. The central 21 degrees of the macula were evaluated using a Goldman III test stimulus presented for 200ms in a supra-threshold Go/No-go target detection paradigm.
Results: :
Scotomatous loci were defined as testing positions that elicited no participant response. Central field loss was calculated as the ratio of scotomatous loci versus non-scotomatous loci. Eyes with fewer scotomatous loci show lower contrast detection thresholds (i.e. higher contrast sensitivity; M: 1.16, SD: .24) than eyes with more scotomatous loci (M: .81, SD: .22). There was a moderate correlation between extent of central field loss and contrast sensitivity (r=.51), and a weaker correlation between central field loss and acuity (r=.31).
Conclusions: :
We show that contrast sensitivity is lower in eyes with greater extent of field loss as assessed by macular perimetry. Future research may investigate more precise contrast sensitivity measures as a way to assess extent of central field loss.
Keywords: contrast sensitivity • age-related macular degeneration • perimetry