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Viral Sheth, Irene Gottlob, Sarim Mohammad, Rebecca J McLean, Frank A Proudlock; Visual field deficits in albinism. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2659.
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© ARVO (1962-2015); The Authors (2016-present)
Albinism is associated with known retinal deficits such as foveal hypoplasia, a midline shift in the line of decussation and optic nerve head abnormalities. Visual field results in albinism are difficult to interpret because of the problem of nystagmus. We have compared visual fields in albinism to a nystagmus cohort without obvious retinal deficits (idiopathic infantile nystagmus or IIN). Results were compared to structural retinal deficits measured using optical coherence tomography (OCT).
Visual field testing was completed monocularly using a Humphrey Field Analyzer on 61 participants with albinism and 32 with IIN. 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. We analyzed each quadrant (upper nasal, upper temporal, lower nasal and lower temporal) of the visual field excluding the blind-spot. We also compared central detection thresholds to the layer thicknesses at the fovea and across the parafoveal region in 99 eyes with albinism and 54 eyes with IIN assessed using OCT.
The detection threshold in albinism was significantly worse compared to the IIN group for all quadrants compared to IIN (p<0.01). Detection thresholds were also significantly worse in the left eye compared to the right (p=0.008) for albinism. In albinism the upper nasal visual field was significantly worse than the upper temporal (p=0.004), lower temporal (p=0.013) and lower nasal (p=0.02) fields. There were no significant differences between the quadrants or eyes in the IIN group. We found significant correlations between central detection threshold and retinal thickness across the parafoveal region (p=0.016), retinal nerve fiber layer (p=0.002 at fovea, p=0.001 across parafovea), inner nuclear layer (p=0.005 at fovea), outer nuclear layer (p=0.001 at fovea, p=0.003 across parafovea), outer segment (p=0.005 at fovea). No significant correlations were found for the IIN group.
Light spot detection thresholds provide further insight into the cortical re-organization occurring in albinism. They also demonstrate that upper / lower visual pathway asymmetries as well as nasal / temporal asymmetries exist in albinism. OCT findings indicate that detection thresholds relate to structural abnormalities of the retina showing that there is clinical value in performing visual fields in albinism.
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