Comparison of Diopsys Pattern Reversal Visual Evoked Potential Responses and Grating Acuity Measurements using the Teller Acuity Card Procedure

Abstract

Purpose: To test the utility of the Diopsys-NOVA Pattern Reversal Visual Evoked Potential (VEP) in measuring visual function in pre-verbal children age 3 to 36 months from an at risk cohort as compared to grating acuity measured using the Teller Acuity Card (TAC) Procedure.

Methods: Subjects were 7 to 26 month old children with birth weight < 2200g or > 2800g who were considered "at risk" for developmental problems. Subjects were randomly assigned to complete the VEP or TAC testing first. All testing was conducted binocularly. VEP measurements were obtained by a clinician trained and experienced in electrophysiology. Measurements were attempted for 0.26, 0.55, 1.11, 2.27, 4.54,and 8.77 cycles/degree (cy/deg) stimuli. TAC testing was conducted by trained and experienced testers. For both VEP and TAC testing, the examiner rated confidence in the result based upon a 5 point scale, with 5 highest confidence (child extremely cooperative/attentive) and 1 lowest (child uncooperative/inattentive). VEP data included amplitude and latency for each spatial frequency stimulus. Grating acuity results were converted into log cy/deg for analysis. Correlation analysis was used to compare TAC results to VEP responses with a confidence of >3. Children with known ocular abnormalities were excluded from analysis.

Results: Testing was attempted on 28 children. One child was unable to complete both VEP and TAC testing. For testable children, tester confidence was significantly better for the TAC procedure (4.69 vs 3.42, p <0.001). There was a significant correlation between TAC acuity and VEP amplitude with the 0.26 cy/deg stimulus (r=0.45, p <0.05).

Conclusions: There was some agreement between TAC and VEP results. Cooperation with the TAC procedure was significantly better than the VEP procedure. For several children the VEP results were judged by the examiner to be not sufficient quality for scoring (confidence <3). Results of this preliminary study suggest that the VEP method used here is not likely to be useful in routine visual screening of young children in this age group. The TAC method, although reliable, is also not feasible for routine screening as it requires a trained and experienced tester.

Keywords: 709 screening for ambylopia and strabismus • 754 visual acuity • 556 infant vision