Purpose: Glare is a vexing effect of intense light and reflections off object surfaces or ocular media. We tested if glare disability increases with visual attention decline. Methods: 107 licensed drivers participated: 79 were neurologically normal, 7 had mild AD, and 21 had focal cerebral lesions, mostly from stroke. Acuity on the ETDRS chart was scored in terms of log minimum angle resolvable (Ferris et al., 1982). To assess glare disability, we subtracted acuity scores under standard lighting from acuity scores under 3 glare levels (21.68, 234.6 & 1096 cd/m2) provided by a light shining in the viewer's eye (Marco Inc., Jacksonville). We measured selective attention using the Visual Attention Analyzer 3000 (subtest 3, Vision Resources, Chicago), and contrast sensitivity using the Pelli-Robson chart. Results: As a group, subjects showed progressive drops in acuity with increasing levels of glare (P<0.001). Drivers with selective attention defects (>=350 ms to achieve 75% correct identification of a target among 23 similar distracters; N=16) had greater disability at high glare levels (P=0.005) than those with normal attention; the difference at medium glare approached significance (P=0.055). Degree of glare disability correlated positively with selective attention impairment (Spearman r=0.337; P<0.001) and negatively with contrast sensitivity (r=-0.303; P=0.002). Conclusions: Drivers with attention impairments from differing causes show greater glare disability. They are less able to ignore irrelevant distractions and recover signal from a noisy background created by glare. Glare disability is not explained by poor acuity but does correlate with impaired contrast sensitivity.
ASJC Scopus subject areas
- Sensory Systems