The effect of binocular blindness in critical period on visual white matter pathways: a single case study

Abstract

Purpose : This study aimed to analyze the effect of binocular blindness in critical periods on visual white matter pathways.

Methods : We have previously reported that diffusion MRI measurements along early visual white matter pathways (the optic tract; OT and optic radiation; OR) acquired from patients of adult-onset eye diseases (glaucoma, leber hereditary optic neuropathy, and cone-rod dystrophy) differ from those acquired from healthy controls (Ogawa et al., 2014; Takemura et al., 2019). However, few studies have analyzed how early blindness affects tissue properties of visual white matter pathways. Here, we acquired diffusion MRI from a male in their 40s with congenital glaucoma (CG) who went binocular blind around 7 to 8 years old using 3T MRI (SIEMENS Trio Tim). We compared his diffusion measurements along OT and OR with age matched healthy controls (n=25, female=11) and glaucoma groups (n=10, female=4). Datasets obtained from healthy controls and glaucoma subjects were already analyzed in a previous study (Ogawa et al., 2021).
We applied probabilistic tractography to identify the OT and OR (Sherbondy et al., 2008). We then estimated fractional anisotropy (FA) along the OT and OR in all subjects, and then compared FA of CG from that of other groups.

Results : The diffusion measurements in the OT and the OR of CG were significantly different from those of the other two groups. In both OT and OR, CG showed significantly smaller FA compared with those in the glaucoma group (OT: d’ = 3.75, p = 0.03; OR: d’ = 5.40, p = 0.001) and the healthy controls (OT: d’ = 5.26, p = 0.005; OR: d’ = 7.68, p < 0.001).

Conclusions : Our preliminary analysis suggests that white matter tissue changes occurring in CG is significantly bigger than those in the glaucoma group. The results raise a possibility that the complete loss of binocular visual input occurred during the visual critical period may cause bigger changes in the microstructure of visual pathways.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.