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Paula Y Sacai, Nivea Nunes Cavascan, Daniel Martins Rocha, Solange Rios Salomao, Adriana Berezovsky; Grating Acuity Maturation Measured by Sweep-Vep in Children with Cerebral Visual Impairment. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4120.
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© ARVO (1962-2015); The Authors (2016-present)
Cerebral visual impairment (CVI) is bilateral visual deficit caused by damage to the posterior visual pathway and/or the visual cortex. Current literature reports great variability in the prognosis of CVI. The purpose of this retrospective observational longitudinal cohort study was to evaluate grating acuity in children with CVI measured by sweep visual evoked potentials (sweep-VEP).
This study was approved by the Committee on Ethics in Research of UNIFESP (0349/08). A group of 18 patients (9 males) with CVI had their grating acuity (GA) longitudinally assessed by sweep-VEP in at least three consecutive visits. Age at first visit ranged from 1.74-64.17 months (mean=15.61±15.16; median=10.54). The time between the first and the last measures ranged from 14.04-94.77 months (mean=31.69±21.03). Grating acuity deficit (GAD) was calculated by subtracting acuity thresholds from mean visual acuity value using age norms according to our own normative data. Deficits were categorized as mild (0.2≤GAD<0.4 logMAR), moderate (0.4≤GAD<0.9 logMAR) or severe (GAD≥0.9 logMAR). Paired t-test was used to compare initial and final GAD. Statistical significance was considered as p≤0.05. The rate of maturation was calculated as the slope of the best-fit line relating to logMAR GA to age in log months.
At the first visit GAD ranged from 0.15-1.33 logMAR (mean=0.49±0.31; median=0.35) and it was severe in 4 children (22.22%), moderate in 10 (55.56%), and mild in 4 (22.22%). The average difference between initial and final measures of GA was 0.14 log unit, however only 13 children showed maturation in GA, 1 child remained stable and 4 children presented final GA worse than initial. The final GAD was significantly larger when compared to the initial one (Paired t-test, Wilcoxon; W=117.000; p=0.009). Mean GA maturation rate was 0.19 logMAR/log months, with children with CVI showing slower maturation rates when compared with normal controls.
Improvement in grating acuity can occur over time in children with CVI. Despite maturation has been found in 72% of cases, their rate of improvement was below the expected. Comprehension of changes in vision function is important for therapeutic planning and rehabilitation programs for this condition.
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