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Nívea Cavascan, Paula Sacai, Solange Salomao, Adriana Berezovsky; Grating acuity deficit and interocular acuity difference in children with cerebral visual impairment. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2362.
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Cerebral visual impairment (CVI) is a pediatric neurological condition due to post-chiasmatic brain lesion which causes bilateral visual loss. It is the most important cause of childhood blindness in industrialized countries. The purpose of this study was to determine grating acuity deficit (GAD) magnitude measured by sweep visual evoked potentials (sweep-VEP) and interocular acuity difference (IAD) in children with CVI.
A retrospective cross-sectional observational study was performed including all children with CVI referred to our laboratory in the last 10 years for grating acuity measurement using the sweep-VEP technique. CVI diagnosis was based on: poor visual behavior, evidence of post-chiasmatic insult and normal fundus. GAD was calculated for the better acuity eye by subtracting acuity thresholds from mean normal visual acuity according to age norms from our own laboratory. Maximum acceptable IAD was 0.1 logMAR. Deficits were categorized as mild (0.2≤GAD<0.4 logMAR), moderate (0.4≤GAD<0.9 logMAR) or severe (GAD≥0.9 logMAR).
A group of 115 children (66 males, 57.39%) with ages ranging from 1.15 to 166.53 months (mean=29.97±29.99, median=17.72) was studied. GAD ranged from 0.17 to 1.28 logMAR (mean=0.68±0.27; median=0.71). Mild GAD was found in 23 (20.00%) children, moderate in 70 (60.87%) and severe in 22 (19.13%). GAD was significantly larger in children who were taking anti-seizures medication (t=-3.4387; P=0.0008). GAD was comparable for gender, etiology (prematurity, seizures, perinatal hypoxia, etc), inclusion in rehabilitation programs, or presence of strabismus and/or nystagmus. IAD ranged from 0 to 0.49 logMAR (mean=0.06±0.08; median=0.04). Normal IAD was found in 96 (83.48%) children.
CVI caused moderate or severe grating acuity deficit in more than two-thirds of the examined children and it was evidently larger for children taking anti-seizure medication. Both eyes had the same magnitude of vision loss, as shown by unremarkable interocular acuity differences in the vast majority of cases. The magnitude of visual acuity deficit might be useful for therapeutic planning, early educational and rehabilitation programs for these patients.
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