Flash Visual Evoked Potential versus Pattern Visual Evoked Potential in the Diagnosis of Strabismic Amblyopia

Abstract

Purpose: To compare the responses of flash visual evoked potential (FVEP) & pattern visual evoked potential (PVEP) in amblyopic eyes with the eyes of healthy children and to find out whether the flash VEP can help us in the diagnosis of amblyopia as it is the only test applicable to nonverbal and disabled children. Methods:We included 60 children with unilateral amblyopia, their age ranging between 4 and 10 years. Thirty age and sex matched healthy children were included as a control group. The included children underwent complete ophthalmologic evaluation with focus on subjective monocular visual acuity, cycloplegic refractions, slit-lamp examination, fundus examination, orthoptic evaluation, stereoacuity, worth 4-dot test, FVEP & PVEP. All participants had stable fixation. Results:The flash VEP P100 latency showed a statistical insignificant difference between the two studied groups (120.6 ± 13.45 & 116.0 ± 14.7 ms respectively) (p = 0.07). However, the pattern VEP P100 latency in amblyopic group (130.5 ± 6.8 ms) was statisticaly longer than that of control group (111.9 ± 4.2 ms) (p = < 0.0001). The amblyopic best corrected visual acuity (BCVA) showed significant correlation with the pattern VEP latency and amplitude (P < 0.001, < 0.001), however, it showed insignificant correlation with the flash VEP latency (P = 0.66). Conclusion:Pattern VEP could be applied to diagnose amblyopia, but we cannot rely on the FVEP in this context as proved with multiregression analysis which showed that the pattern VEP latency and amplitude are the most important determinant factor for amblyopic best corrected visual acuity.