Retinal abnormalities in human albinism translate into a reduction of grey matter in the occipital cortex

Albinism is a genetic condition associated with abnormalities of the visual system. Defects in melanin production cause underdevelopment of the fovea, reduced retinal cell numbers and abnormal routing of ganglion cell nerve fibres at the optic chiasm. We examined 19 subjects with albinism and 26 control subjects to determine whether retinal abnormalities affect the structure of the visual cortex. Whole-brain, high-resolution anatomical magnetic resonance imaging volumes from each subject were obtained on a 1.5-T scanner and segmented into grey and white matter. A voxel-wise statistical comparison of grey and white matter volumes in the occipital lobes between the two groups was performed using voxel-based morphometry. Our analysis revealed a regionally specific decrease in grey matter volume at the occipital poles in albinism. The location of the decrease in grey matter corresponds to the cortical representation of the central visual field. This reduction is likely to be a direct result of decreased ganglion cell numbers in central retina in albinism.