Development of visual acuity in children with cerebral visual impairment.

OBJECTIVE: To study the development of visual acuity in term-born children with cerebral visual impairment and a history of neonatal hypoxic-ischemic encephalopathy.
METHODS: We studied 19 term-born children, aged 6 months to 6 years, with moderate to severe neonatal hypoxic-ischemic encephalopathy and behaviors indicative of cerebral visual impairment. Longitudinal measures of grating acuity were obtained using preferential looking (PL) and visual evoked potential (VEP) procedures. Visual acuities at first and last visits were compared. The courses of acuity development in the 9 children who underwent both VEP and PL acuity assessment at 4 or more ages were compared with normal development.
RESULTS: All children had measurable PL and VEP acuity, despite poor visual behavior. In nearly all, both PL and VEP acuity were below normal for age. For both PL and VEP measures, acuity at the last visit was, on average, 1 octave better than at the first visit, with a rate of improvement lower than normal. Although parallel courses of PL and VEP development occurred in many, substantial disparities in PL and VEP acuity were observed in others.
CONCLUSIONS: Modest increases in PL and VEP grating acuity occur during early childhood in many of these patients. The rate of increase is lower than normal.