正常视野与实验性暗区的多焦视诱发电位特征分析

目的分析正常眼不同视野区域的mfVEP波形特征及实验性暗区对结果的影响，探讨mfVEP用于客观评定视野的可行性。方法以正常青年男性51眼为实验对象，应用四通道mfVEP记录系统进行mfVEP检测，30眼行实验性暗区测试。统计组合反应波振幅、峰时及振幅密度的均数、标准差。组问比较采用单因素方差分析，不同刺激野遮盖前、后mfVEP振幅比较采用配对t检验。结果正常眼mfVEP各位点均能引出较明确的VEP波：其中鼻下、颞下象限组合反应波振幅密度（8．68±3．67、7．84±3．32nV／deg2）较鼻上、颞上象限（5．55±2，22、5．08±1．85nV／deg2）大；反应波从黄斑中心凹向周边逐渐降低（240．36±96．60nV／deg2-1．83±O．73nV／deg2）。遮盖颞下象限及外周3个环刺激野造成形成实验性暗区时，对应区域mfVEP组合反应波多数呈熄灭型（70％及80％）；而遮盖鼻下方某两个位点时，对应区域波振幅显著降低（P〈0．05）。结论mfVEP能较准确、客观反映视野不同区域的视功能差异，有望成为法医学客观视野检测手段。

Multifocai VEP studies of normal visual fields and experimental scotoma

Objective To investigate the waveform characteristics of optimization four-channel muhifocal VEP and experimental scotoma in normal visual fields, try to find the feasibility of mfVEP as an objective evaluation standard. Methods The multifocal VEP with four-bipolar channel recording was performed using the RETI-Port/Scan system. 51 eyes of healthy young males were measured with full field stimulation, and then 30 eyes were measured with inferior-temporal quadrant, outer threerings area or two sectors covered. The main wave peak-to-trough amplitude, latency and amplitude density were measured and calculated. The peak- to-trough amplitudes in different field before and after covering were analyzed and compared. Results VEP responses could be identified in almost all sectors in healthy males, the amplitude densities at inferior-nasal （8.68 ± 3.67nV/deg2 ）, inferior-temporal quadrant （ 7.84± 3.32nV/deg2 ） were greater than that at superior- nasal（5.55 ± 2. 22nV/deg2 ）, superior-temporal quadrant （5.08 ± 1.85nV/deg2）. The amplitude densities were greatest at the central fovea （240.36 ± 96.60nV/deg2 ）, the densities reducing towards more peripheral location （i. 83 ± 0.73nV/deg2）. The multifocal VEPs in one quadrant or outer three-rings covered areas were undetectable in most subjects （70%, 80% ）, in two sectors covered areas were obviously decreased, with statistically significant difference in comparison to the full field stimulation mode （ P 〈 0. 05 ）.Conclusions Multifocal VEPs can reflect the visual function at different visual field locations correctly and objectively, which offer the possibility to perform an objective visual field assessment in forensic medicineidentification.