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Y. Bradfield, T.D. France, J. Verhoeve, R.E. Gangnon; Is Sweep VEP Predictive of Recognition Acuity in Albinism? . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1683.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if sweep visual evoked potential (VEP) is predictive of recognition visual acuity in children with albinism.
A retrospective chart review was performed of children with oculocutaneous and ocular albinism who underwent sweep VEP testing from 1992 to 2003. All patients had a complete ophthalmologic examination by a pediatric ophthalmologist, and had sweep VEP testing by a single electrophysiologist at the same institution. The diagnosis of albinism was based on the presence of several of the following features: nystagmus, decreased foveal pigmentation, iris transillumination defect, and asymmetric flash VEP. Only patients with at least 5 years of follow–up were included. When patients were old enough to perform recognition acuity testing, their vision was assessed with either Allen pictures, Sheridan Gardiner, HOTV, or Snellen letters. Positive predictability of sweep VEP was defined as final recognition acuity within 1 logMAR line of sweep VEP. Refractive correction, if prescribed, was worn at the time of acuity testing. The most rigorous test for the child's age and capability was utilized.
Thirteen patients were included in the study. The mean age at initial examination was 2.1 years, with mean follow–up duration 9.5 years (range, 5.5–14.7 years). Eleven patients presented with nystagmus, iris transillumination defects, and foveal hypoplasia. Two additional patients had minimal or no nystagmus, but had foveal hypoplasia and asymmetric flash VEP characteristic of albinism. The mean age at initial sweep VEP was 3.1 years (range, 0.1–10 years). The mean time between initial VEP and initial recognition acuity was 2.4 years. The initial sweep VEP acuity for each patient was used as the target to which future recognition acuity was compared. Five of 13 patients had initial sweep VEP which was predictive of final recognition acuity. An additional 5 patients had final recognition acuity which surpassed initial sweep VEP acuity, ranging from 2–3 lines better acuity. Of these 10 patients, the mean duration for recognition acuity to reach VEP acuity was 5.4 years. There was no correlation between predictive VEP and increased foveal pigmentation, lower refractive error, absence of strabismus or nystagmus, or longer duration of follow–up. There were 3 patients whose VEP overestimated future recognition acuity.
Sweep VEP can be utilized as a predictive tool for recognition acuity in children with albinism. It may take several years for the recognition acuity to reach the initial VEP acuity. Predictability was found amongst a variable clinical spectrum of albinism.
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