Sweep visual evoked potential and visual development in optic nerve hypoplasia

Abstract

Optic nerve hypoplasia (ONH) remains a leading cause of childhood visual impairment. Visual development in infancy and preverbal age in patients with ONH has not been well characterized to date. In this study, we assessed sweep visual evoked potential (VEP) measurements as indicators of early visual development and predictors of final recognition visual outcome in patients with ONH. We retrospectively studied 38 patients with clinically diagnosed ONH who had performed sweep VEP. Final recognition acuity was assessed with Snellen or HOTV letters, if patients were capable. Other factors assessed included presence of nystagmus, CNS malformations, pituitary involvement, and optic nerve size. Most patients had subnormal sweep VEP acuities compared to age-matched normals. VEP acuities reached a plateau by 20 months of age in patients with ONH compared to a plateau at 12 months in normal children, correlating well with recognition acuity performed at an older age. 59% of patients had acuity worse than 20/40, and 11% had acuity 20/200 or worse after 20 months of age. Sweep VEP measurements in ONH suggest a significant delay in visual development, but confirm that there is some improvement in vision until 20 months of age. Final visual acuity correlates with sweep VEP measurements, suggesting that sweep VEP may be used to predict outcomes at an early age. Sweep VEP measurements may be used clinically to provide parents with an accurate visual prognosis for children with optic nerve hypoplasia.