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L. France, E. Stone, T. D. France, J. N. Ver Hoeve; Sweep VEP Acuity Development in Children with Down Syndrome. Invest. Ophthalmol. Vis. Sci. 2007;48(13):957.
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© ARVO (1962-2015); The Authors (2016-present)
Most children with Down Syndrome (DS) have bilaterally reduced acuity and a greatly increased risk of strabismus and amblyopia. Only a small portion of individuals with DS achieve high levels of spatial acuity. The goal of this retrospective study was to determine whether those children with DS and high levels of acuity on follow-up showed evidence of relatively good vision as infants.
The consecutive records of 64 children with DS whose visual acuity had been measured using the sweep VEP method were reviewed. The age at time of test ranged from 2 months to 14 years. 27 tests were performed on infants with DS < 1 yr of age. Follow-up testing was available on 32 infants. The sweep VEP stimulus consisted of a horizontal sine wave grating that linearly increased in spatial frequency while temporally countermodulated at 7.5 Hz. Patients were tested with natural pupils and their current spectacle refraction. Accommodation was monitored in real time using an infrared photorefractor. Only sweep trials with good fixation and accommodation were included in the analysis. The highest sweep VEP acuity recording that was repeatable was considered grating acuity for that day.
The average sweep VEP acuity of patients with DS > 1 yr of age was 12 c/deg, which is signficantly lower than the normal average of 22 +/-2 c/deg for this age range. Sweep VEP acuity remained relatively constant with age. Of the 26 infants with DS with multiple sweep VEP tests, only 2 (6%) had grating acuities > 19 c/deg and both had high sweep acuities for age at the time of the first test. Infants with DS and final acuities in the 12-19 c/deg range (47%) also had moderately reduced acuities for age at the time of the first test. Of infants with DS and acuities in the 6-11 c/deg range (41%) ,7 of 9 had similar acuities when first seen. Of the 2 infants with DS had final acuities below 6 c/deg (6%), all had significantly reduced acuities at the first sweep VEP test.
Children with DS generally have reduced cortical visual acuity. The portion of children with DS and moderate-to-high levels visual acuity also show evidence of relatively better cortical visual processing at an early age.
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