Kelly John P, Phillips James O, Weiss Avery H
Division of Ophthalmology, Roger H. Johnson Vision Lab, Seattle Children's Hospital, OA.5.345, 4800 Sand Point Way NE, W-4753, Seattle, WA, 98105, USA.
Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, 98105, USA.
Doc Ophthalmol. 2017 Feb;134(1):37-44. doi: 10.1007/s10633-016-9568-4. Epub 2017 Jan 5.
The relationship between eye movements and the visual evoked potential (VEP) response was examined in two subjects with infantile nystagmus syndrome (INS). Changes in VEP amplitude were compared between periods of foveation versus periods of high-frequency nystagmus. An analysis is proposed that improves extraction of the checkerboard reversal VEP signal from subjects with INS.
INS subjects were 2 healthy children (12-13 years old) with 20/40 or better corrected acuity. Optical coherence tomography confirmed the optic nerves, retina, and fovea were within normal variation. VEPs were recorded to checkerboard reversal and to onset/offset of horizontal gratings while simultaneously recording the electrooculogram (EOG). VEP epochs underwent Fourier analysis, and epochs were examined for phase consistency with the mean. Foveation periods were compared to video-oculography recordings from a separate session.
Optic nerve misrouting, such as crossed VEP asymmetry seen in albinism, or ipsilateral VEP asymmetry seen in achiasma, was not detected in either subject. By averaging only epochs in which EOG epochs showed foveation, VEP amplitude could be increased ≥59%. Averaging the VEP only on epochs with consistent phase at Oz increased VEP amplitude by ≥twofold; subsequent EOG epochs after this analysis mostly contained foveation periods or minimal EOG activity. Latency varied <14 ms across all analyses.
The checkerboard reversal VEP signal is dependent on foveation periods in subjects with INS despite good visual acuity. Reduction in VEP amplitude due to retinal image motion induces noise and/or lack of phase locking in the VEP epochs. Selective averaging of epochs based on phase consistency improves the extraction of a VEP signal, likely when retinal image motion is minimized.
在两名患有婴儿型眼球震颤综合征（INS）的受试者中研究眼球运动与视觉诱发电位（VEP）反应之间的关系。比较了注视期与高频眼球震颤期之间VEP振幅的变化。提出了一种改进从INS受试者中提取棋盘格翻转VEP信号的分析方法。
INS受试者为2名健康儿童（12 - 13岁），矫正视力为20/40或更好。光学相干断层扫描证实视神经、视网膜和中央凹在正常变异范围内。记录了对棋盘格翻转以及水平光栅起始/偏移的VEP，同时记录眼电图（EOG）。对VEP片段进行傅里叶分析，并检查片段与平均值的相位一致性。将注视期与另一次单独检查的视频眼动图记录进行比较。
在两名受试者中均未检测到视神经错向，如白化病中所见的交叉VEP不对称或无交叉视路中所见的同侧VEP不对称。仅对EOG片段显示注视的片段进行平均，VEP振幅可增加≥59%。仅对Oz处相位一致 的VEP片段进行平均时，VEP振幅增加≥两倍；此分析后的后续EOG片段大多包含注视期或最小EOG活动。在所有分析中潜伏期变化<14毫秒。
尽管视力良好，但INS受试者的棋盘格翻转VEP信号依赖于注视期。视网膜图像运动导致的VEP振幅降低会在VEP片段中引入噪声和/或缺乏锁相。基于相位一致性对片段进行选择性平均可改善VEP信号的提取，可能是在视网膜图像运动最小化时。
