Abstract
Purpose :
Our earlier studies demonstrated temporal contrast sensitivity reduction (i.e., desensitization) due to flicker adaptation in visually normal subjects and glaucoma patients using the steady-pedestal paradigm. A larger desensitization effect was observed in glaucoma patients than in the control subjects. The current study investigated whether flicker adaptation in the pulsed-pedestal paradigm have a desensitization effect or not in glaucoma patients.
Methods :
Contrast sensitivity was measured in the pulsed-pedestal paradigm on two groups of subjects: 6 glaucoma patients and 9 age-matched control subjects. The stimulus consisted of a pedestal array of four luminance squares presented on a CRT monitor. Subjects adapted to: (1) a steadily presented background luminance of 15 cd/m2 in the non-flicker adaptation condition, and (2) a 7.5 Hz high contrast square-wave luminance flicker with a time-averaged luminance of 15 cd/m2 in the flicker adaptation condition. In each test trial, the four-square array with higher luminances than the background luminance was presented for 266 ms. One of the four squares was randomly chosen to have a higher luminance than the other three, and the subjects were to identify this unique square. For each subject, contrast sensitivity was estimated using staircase procedures and primate physiology-based models in each adaptation condition. A linear mixed model was used to test the statistical difference on the contrast sensitivities between patient groups, adaptation conditions, and the interaction.
Results :
Results revealed: a significant main effect of patient group (p=0.02), suggesting lower contrast sensitivity in glaucoma patients than in control subjects; a non-significant main effect of adaptation condition (p=0.542); and a non-significant interaction effect (p=0.524).
Conclusions :
Contrast sensitivity estimated from the pulsed-pedestal paradigm is significantly reduced for glaucoma patients compared to visually normal subjects. Flicker adaptation does not show a desensitization effect on either group of subjects. The pulsed-pedestal paradigm may or may not reveal the contrast sensitivity in the parvocellular pathway, but it showed different effects than the steady-pedestal paradigm on glaucoma and visually normal subjects, suggesting that different visual contrast processes are involved in these two paradigms.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.