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Viral Sheth, Irene Gottlob, Zhanhan Tu, Sarim Mohammad, Rebecca McLean, Frank A Proudlock; Comparison of retinal and cortical structures with visual fields in albinism. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5979.
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© ARVO (1962-2015); The Authors (2016-present)
We have previously reported visual field (VF) deficits in albinism which were more severe in the upper nasal visual field and also in the left eye. We now investigate whether these VF deficits are related to retinal or cortical abnormalities, comparing peripapillary retinal nerve fiber layer (ppRNFL) distributions) and occipital pole grey matter thickness, volume and surface area measurements to these VF deficits.
VF testing and optic nerve optical coherence tomography (OCT) was completed on 71 eyes with albinism. In all participants monocular light spot detection threshold were assessed using automated white on white perimetry with a SITA 24-2 algorithm to compare the detection threshold for up to 24° around the fixation point. Detection thresholds were analysed in separate quadrants (upper nasal, lower nasal, upper temporal and lower temporal) of the VF. The optic nerve OCT B scan images required manual motion correction due to nystagmus using Image J. ppRNFL thickness was analysed on the realigned volumes using Copernicus OCT software comparing corresponding visual field quadrants and ppRNFL sectors. Magnetic resonance imaging (MRI) data collected on 18 participants was segmented using Freesurfer software to calculate occipital pole gray matter thickness, volume and surface area.
We found no significant correlations between detection thresholds in four visual field quadrants and corresponding ppRNFL segments. The ppRNFL adjacent to the macula and central foveal detection threshold were correlated in the left eye only (p=0.034). We found no significant correlations between detection thresholds and either occipital pole thickness, volume or surface area for the right eye. However a significant correlation between the lower nasal visual field in the left eye and right occipital volume (p=0.009) was observed. Occipital pole volumes and surface areas were also much greater in the right compared to the left cortex (p<0.0001).
VF quadrant deficits do not relate to ppRNFL distribution in albinism. In contrast we found correlations between the lower nasal visual field and right occipital cortical gray matter volume. Occipital pole differences between the two cortices may underlie VF deficits differences observed between the right and left eyes in albinism. These results suggest that visual field deficits are likely to be cortical in origin.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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