Abstract
Purpose: :
Cortical visual impairment is one of the most common causes of bilateral visual impairment in young children. Visual development can occur but is usually slow. Reports show that a modest increase in VEP and grating acuity occur during early childhood in these patients (Lim 2005). Sweep and flash VEPs are often used as a measure of visual function in these patients. But studies correlated the sweep and flash VEPs are rarely found. The purpose of this study was to determine the relationship of sweep and flash VEPs in infants with CVI
Methods: :
Five infants from 1.7 to 10 months old (mean = 5.3±1.6 months) with CVI had complete ophthalmic evaluation and were tested with both flash and sweep VEPs. Flash VEP latencies (P2 wave) and sweep VEP grating acuity thresholds were the primary outcome variables. Statistical testing was performed to determine correlation between these variables.
Results: :
There was an exponential decrease in grating threshold in sweep VEP and latencies in flash VEP across age. VEP values of both tests were below mean of normal for age. However, there was a significant correlation between the flash and sweep VEP (P<0.05). The lower the grating acuity threshold, the shorter the latencies in flash VEP.
Conclusions: :
These findings demonstrate a significant correlation between flash and sweep VEP in infants with CVI. Slow but gradual cortical development can be associated with slow improvement of visual function measures in infants with CVI.
Keywords: infant vision • visual impairment: neuro-ophthalmological disease • electrophysiology: clinical