Abstract
Purpose :
Abnormal responses during binocular rivalry have been reported in patients with mild glaucoma when using traditional stimuli. In this study, we tested binocular rivalry using complex images (i.e., face, house) to probe the integrity of higher order visual processing. These stimuli are broadband in spatial frequency and orientation and are processed in stimulus-specific areas: fusiform face area (FFA) for face and parahippocampal place area (PPA) for house.
Methods :
Seven patients (4F/3M, 61±7 years old) with mild glaucoma and 9 healthy controls (5F/4M, 51±11 years old) participated. The 2 groups were equivalent in visual acuity and stereo-acuity. Rivalry stimuli were gray-scale images of a house and a face, presented in 4.5 x 6deg rectangular areas, viewed dichoptically. There were 3 stimulus location presentation conditions: centrally, and eccentrically at 3deg in the right (RH) and in the left hemifield (LH), respectively. A 0.5deg fixation cross was presented centrally in all conditions. Participants kept their gaze stable on the cross and used a button-response box to indicate if they perceived the house, the face, or both. The outcome measures were rivalry rate (i.e., switches/min) and time of exclusive dominance of the face or house percept.
Results :
A 3 (location: central, LH, RH) x 2 (group: glaucoma, control) mixed factorial ANOVA revealed that rivalry rate was significantly higher for the control group than for the glaucoma group in the LH, F(2,28) = 3.72, p = 0.03. Compared to central and RH locations, rivalry rate in the LH was highest for the control group (17±6 switches/min) and lowest for the glaucoma group (12±6 switches/min). For the control group, the face dominated 24% longer than the house in the LH location, but the 2 stimuli dominated equally in the central and RH locations. For the glaucoma group, the time dominance for the face percept was 22%, 30%, and 34% longer than the house in the central, LH, and RH conditions, respectively.
Conclusions :
Binocular rivalry with complex stimuli produces different pattern of responses compared with traditional stimuli. The control group showed a lateralization of responses that mirrors the FFA’s laterality (i.e., FFA is larger in the right hemisphere). Overall, patients with mild glaucoma have stronger responses to faces than to houses, indicating that the function of stimulus-specific areas of FFA and PPA may be unequally affected.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.