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A Weiss, JP Kelly; Vep Correlations With Anisometropic and Strabismic Amblyopia in Children Before and After Patching . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2940.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To characterize VEP abnormalities in young children with anisometropic and strabismic amblyopia prior to and after patching. Methods: Twenty-four children (2 - 7 years age, median = 4.7) with anisometropia (≷ 1.5D spherical equivalence) and/or esotropia underwent complete ophthalmological exam. Acuity was measured by Teller cards or Snellen or Allen optotypes. VEPs (Oz referenced to Cz, ground at Pz) were measured to check reversal (163-18'; CR) and sinewave grating onset-offset (0.5 - 4 cy/deg; PO) all at constant luminance. Nine patients had recordings after patching (minimum: 1 week / year age). VEP amplitudes were normalized to minimize intersubject variation. Results: Normalized amplitudes of the P100 peak for CR stimuli and P1 and N2 peaks for PO stimuli were reduced across all spatial frequencies in the amblyopic eye (F ≷ 14.2; p 3.6; p < 0.05) and was marginally significant for the P1 peak for PO (F = 2.4; p =0.06). Significant latency differences between the amblyopic eye and the non-amblyopic eye were observed for the 163' and 84' checks and the 0.5 cy/deg PO grating. After patching, on average the amblyopic eye showed an increase in amplitude that was most pronounced at the lowest and highest spatial frequencies. Latencies decreased but abnormalities in waveforms persisted. No single VEP parameter correlated highly with initial or final acuity (r2 < 0.35). Stepwise multiple regression suggested that final acuity could be predicted by a linear combination of P1 latency across 3 spatial frequencies (adjusted R2 = 0.74; p < 0.001). Conclusion: The data show a change in the spatiotemporal response, which is characterized by a loss of high spatial frequency inputs, resulting in a low-pass spatial tuning function and temporal delays. A combination of latency changes to pattern-onset stimulation was predictive of follow-up acuity. Despite a trend for normalization of amplitude and latency after occlusion, VEP abnormalities persist despite normal acuity.
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