Pattern reversal visual evoked potentials following early treatment of unilateral, congenital cataract
D. L. McCulloch and B. Skarf
Department of Ophthalmology, Hospital for Sick Children, Toronto, Ontario.
OBJECTIVE: To describe the pattern reversal visual evoked potentials (VEPs)
that were used to monitor and quantify early visual development following
treatment for dense, unilateral, congenital cataract. DESIGN: Longitudinal
prospective study. PATIENTS: Six infants who underwent surgery and contact
lens correction before age 5 months and who had good compliance with
occlusion therapy throughout the first 3 years of life. RESULTS: Initially,
VEPs from aphakic eyes showed marked abnormalities, including small
amplitudes, prolonged latencies, missing components, and absent VEPs to
small check sizes. Threshold check size was elevated by 3 octaves or more.
With part-time occlusion of the opposite eye, VEPs normalized rapidly in
the first year, but residual deficits remained to age 4 years when visual
acuities were between 20/50 and 20/120 in aphakic eyes. Threshold check
size clearly differentiated between aphakic and normal eyes and was the
only VEP parameter that was correlated with single-letter visual acuity.
Thus, threshold check size had greater clinical use than measures of
pattern VEPs based on latency, amplitude, or waveform. CONCLUSIONS:
Patients treated for unilateral congenital cataract, who have early surgery
and contact lens correction and comply with occlusion therapy, show a
period of rapid VEP maturation and have a good visual prognosis.
