Abstract
Purpose :
To assess the effect of glare on mesopic contrast sensitivity function at different levels of illuminance using a standalone glare source.
Methods :
Binocular mesopic contrast sensitivity function (CSF) was measured in 12 normally sighted young adults (aged 19 to 32 years) using the qCSF procedure. The testing screen has a background luminance of 0.10 cd/m2. A Fiilex P360S LED light with a dome diffuser was used as the standalone glare source, and was situated at a 30° angle from the left, at eye level, facing the observers. We examined seven glare levels (0, 9, 27, 37, 70, 131, and 266 lux) with two blocks for each level of illuminance. The testing sequence was set up in an ascending order for one set of blocks and in a descending order for the other set. Proper dark adaptation was administered before each block, as needed. The area under log CSF (AULCSF) across spatial frequencies of 1.5 to 18 cycles/degree was used as a summary metric for CSF. Contrast sensitivity (CS) at 6 cycles/degree was also examined. FDR correction was applied for multiple comparisons.
Results :
Both AULCSF and the CS at 6 cycles/degree exhibited monotonic fall-off with increasing glare level, with the CS at 6 cycles/degree having greater overall variability. The average AULCSF were 1.22±0.04 (SE), 1.17±0.04, 1.10±0.05, 1.02±0.05, 0.92±0.05, 0.82±0.05, and 0.64±0.05 for 0, 9, 27, 37, 70, 131, and 266 lux, respectively. The corresponding CS at 6 cycles/degree were 1.19±0.05, 1.12±0.06, 1.07±0.08, 0.99±0.07, 0.87±0.08, 0.80±0.08, and 0.61±0.08, respectively. When the illuminance of the glare source was increased to 27 lux, both AULCSF (t(11) = 4.48, p=0.001) and CS at 6 cycles/degree (t(11) = 3.13, p=0.01) decreased by 0.12 log units in comparison to the no-glare condition.
Conclusions :
The presence of glare, even at relatively low illuminance levels, can have a significant detrimental effect on mesopic contrast sensitivity function.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.