Abstract
Purpose :
Stereoscopic disparity is processed at different spatial scales across different regions of the visual field (Maiello et al, 2017). In glaucoma, progressive loss of retinal ganglion cells results in visual field defects as well as impaired stereoacuity (Essock et al., 1996). Here, we assess whether and how disparity processing at different spatial scales is impaired in glaucoma. We further ask whether glaucomatous damage impairs the integration of disparity information across the visual field.
Methods :
Fourteen glaucoma patients (mean±SD age: 64±6 years; mean±SD stereoacuity: 79±95 arcsec), fifteen normally-sighted age-matched controls (60±7 years; 48±16 arcsec), and ten young normally-sighted controls (24±4 years; 41±3 arcsec) were included in the study. Observers viewed pink noise stereograms containing tilted (45° or 135°) sinusoidal corrugations at different modulation spatial frequencies. The corrugation filled a central 21° circular region, or was confined to annular regions spanning 0°-3°, 3°-9° or 9°-21°. Participants indicated the orientation of the corrugation. To evaluate whether disparity information is optimally integrated across the visual field, human observers’ performance was pit against the optimal model performance.
Results :
Human disparity sensitivity was consistently bandpass tuned across different portions of the visual field (Fig. 1a-c), and tuning shifted from high to low frequencies moving from the fovea to the periphery (Fig. 1d, p<0.001), independently of age or disease status (p = 0.21). Peak disparity sensitivity decreased from the fovea to the periphery (Fig. 1e, p<0.001), and varied across study groups (Fig. 1f, p<0.01). Specifically, older controls had impaired sensitivity compared to young participants (p<0.05), and glaucoma patients had impaired sensitivity compared to both young (p<0.01) and age-matched controls (p<0.05). However, for patients and controls alike (p=0.094), the envelope of disparity sensitivity for the full field stimulus was the near-optimal combination of sensitivities across the annular regions (Fig. 1g).
Conclusions :
We provide a map of glaucomatous impairments in disparity processing throughout the visual field and across spatial frequencies. In spite of impaired disparity sensitivity, glaucoma patients maintain near-optimal integration of disparity information across different regions of the visual field.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.