Kelly John P, Tarczy-Hornoch Kristina, Herlihy Erin, Weiss Avery H
Roger H. Johnson Vision Lab, Seattle Children's Hospital, Division of Ophthalmology, 4800 Sand Point Way NE, Seattle, WA 98105, United States; University of Washington Medical Center, Department of Ophthalmology, Seattle, WA 98105, United States.
Roger H. Johnson Vision Lab, Seattle Children's Hospital, Division of Ophthalmology, 4800 Sand Point Way NE, Seattle, WA 98105, United States; University of Washington Medical Center, Department of Ophthalmology, Seattle, WA 98105, United States.
Vision Res. 2015 Sep;114:142-50. doi: 10.1016/j.visres.2014.11.014. Epub 2014 Dec 19.
The visual evoked potential (VEP) generated by the amblyopic visual system demonstrates reduced amplitude, prolonged latency, and increased variation in response timing (phase-misalignment). This study examined VEPs before and after occlusion therapy (OT) and whether phase-misalignment can account for the amblyopic VEP deficits. VEPs were recorded to 0.5-4cycles/degree gratings in 10 amblyopic children (2-6years age) before and after OT. Phase-misalignment was measured by Fourier analysis across a limited bandwidth. Signal-to-noise ratios (SNRs) were estimated from amplitude and phase synchrony in the Fourier domain. Responses were compared to VEPs corrected for phase-misalignment (individual epochs shifted in time to correct for the misalignment). Before OT, amblyopic eyes (AE) had significantly more phase-misalignment, latency prolongation, and lower SNR relative to the fellow eye. Phase-misalignment contributed significantly to low SNR but less so to latency delay in the AE. After OT, phase-alignment improved, SNR improved and latency shortened in the AE. Raw averaged waveforms from the AE improved after OT, primarily at higher spatial frequencies. Correcting for phase-misalignment in the AE sharpened VEP peak responses primarily at low spatial frequencies, but could not account for VEP waveform improvements in the AE after OT at higher spatial frequencies. In summary, VEP abnormalities from the AE are associated with phase-misalignment and reduced SNR possibly related to desynchronization of neuronal activity. The effect of OT on VEP responses is greater than that accounted for by phase-misalignment and SNR alone.
弱视视觉系统产生的视觉诱发电位（VEP）表现为振幅降低、潜伏期延长以及反应时间变化增加（相位失准）。本研究检测了遮盖疗法（OT）前后的VEP，以及相位失准是否可以解释弱视VEP缺陷。在10名弱视儿童（2至6岁）接受OT前后，记录其对0.5 - 4周期/度光栅的VEP。通过有限带宽的傅里叶分析测量相位失准。从傅里叶域中的振幅和相位同步估计信噪比（SNR）。将反应与经相位失准校正的VEP进行比较（单个时相在时间上移位以校正失准）。在OT之前，弱视眼（AE）相对于对侧眼有明显更多的相位失准、潜伏期延长以及更低的SNR。相位失准对AE中低SNR有显著贡献，但对潜伏期延迟的贡献较小。OT后，AE的相位对齐改善，SNR提高，潜伏期缩短。OT后AE的原始平均波形有所改善，主要在较高空间频率。校正AE中的相位失准主要在低空间频率锐化了VEP峰值反应，但无法解释OT后AE在较高空间频率的VEP波形改善。总之，AE的VEP异常与相位失准和SNR降低有关，可能与神经元活动不同步有关。OT对VEP反应的影响大于仅由相位失准和SNR所解释的影响。
