Abstract
Purpose :
Amblyopia is characterized by visual deficits at high spatial frequencies in measures of contrast sensitivity and binocular vision. Model-based approaches to functional neuroimaging analysis provide a method to map and interrogate how population spatial frequency tuning (pSFT) may differ in early visual cortex between individuals with amblyopia and normally-sighted controls. We consider how voxel-wise spatial frequency tuning varies between the amblyopic and fellow eye and how this tuning varies as a function of receptive field size and eccentricity.
Methods :
We evaluated receptive field size and spatial frequency tuning in two individuals with amblyopia and two controls using model-based functional neuroimaging. Receptive field sizes were derived from monocular pRF mapping (Kay et al., 2013), and preferred spatial frequency and bandwidth were estimated with monocular pSFT mapping, assuming a log Gaussian function (see Aghajari, Vinke, & Ling, 2020). We then compared receptive field size and pSFT estimates between eyes (amblyopic/non-dominant vs fellow/dominant eye) and between subject groups (amblyopia vs control).
Results :
In participants with amblyopia, spatial frequency preferences were significantly lower in the amblyopic eye compared to fellow eye, with the amblyopic eye preferring lower spatial frequencies (p< 0.01) with a wider bandwidth (p<0.01). This interocular difference in spatial frequency preference did not persist in control subjects (p= 0.99). We found that spatial frequency preference decreased with increasing eccentricity in individuals with amblyopia (p< 0.01) and the largest interocular difference in spatial frequency preference was noted at lower eccentricities (<4 degrees of visual angle). Across all individuals, receptive field size increased with eccentricity and there was no significant difference in receptive field size between eyes.
Conclusions :
This work provides evidence that spatial frequency preference is lower and tuning is broader for the amblyopic eye and this difference in preference is most pronounced within the central four degrees of the visual field. In both amblyopia and control groups, receptive field size increased with increasing eccentricity, but there was no significant interocular difference in receptive field size.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.