散光性和远视性视网膜离焦对图形视觉诱发电位P_(100)潜伏值的影响

Effect of retinal defocusing on P_(100) latency of P-VEP

目的定量研究散光性和远视性视网膜离焦对图形视觉诱发电位(P-VEP)P100潜伏值的影响。方法对视力或矫正视力正常的受试者眼前依次放置不同度数的正柱镜片或负球镜片造成不同程度的散光性或远视性视网膜离焦。每一实验镜片条件下行单眼P-VEP检查,记录P100潜伏值。结果当采用较低空间频率刺激时,P100潜伏值随视网膜离焦程度的增加变化不显著;当采用较高空间频率刺激时,P100潜伏值随散光和远视性视网膜离焦度的增加而延长。结论散光性和远视性视网膜离焦均可引起P-VEPP100潜伏值延长;其延长程度不仅与视网膜离焦程度有关,与刺激的空间频率亦有关,低中度视网膜离焦引起P100潜伏值延长在较高空间频率时更为明显。

Objective Researches have revealed that the effect of optical defocus on the steady state pattern reversal visual-evoked response （P-VEP） and the effect of spatial frequency on P-VEP, separately. This study was to evaluate the contribution of different degrees of retinal defocusing to the latency of P-VEP. Methods P-VEP was recorded in 6 normal eyes from health subjects with the uncorrected or corrected visual acuity ≥ 1.0 and 13 eyes dilated-pupil from normal person by eyedrops. Different spatial frequencies of checkerboard pattern stimulus were selected for all the eyes under the varying conditions of retinal defocuse by placing the different diopter of negative cylindrical lens or negative spherical lens in front of eyes. The correlation of retinal defocusing and latency of P-VEP was assessed using Pearson correlation analysis. Present study followed the Statement of Helsinki,and the written informed consent was obtained from all the subjects. This clinical trial was approved by the Ethic Committee of Tianjin Eye Hospital before the examination. Results In normal eyes, no significant correlation was obtained between the absolution values of diopters of negative cylindrical lens or negative spherical lens and abnormality of latency of P-VEP under the spatial frequency of 60＇ are（ r = 0. 083, P 〉 0.05 ）. However, the positive correlation was found between the absolution values of diopters of negative cylindrical lens or negative spherical lens and abnormality of latency of P-VEP under the spatial frequency of 15＇ are （ r = 0. 647, P 〈 0.01 ）. In the dilated-pupil eyes, the positive correlation between the absolution values of diopters of negative cylindrical lens or negative spherical lens and abnormality of latency of P-VEP were found in the eyes with 〉 -5.0 D diopter under the spatial frequency of 60＇ are （r = 0. 468 ,P 〈 0. 01 ） , but the significant correlation was found in any diopter of defocused eye under the spatial frequency of 15＇ arc （ r = 0. 669, P 〈 0.01 ）. Conclusion Retinal defocusing could prolong latency of P100 wave. The latency of P100 wave is affected by both defoeusing of retinal image and spatial frequency of the pattern stimulus.