背景光照明强度对视网膜电图和振荡电位的影响

目的观察不同强度背景光照明下视网膜电图(electroretinogram, ERG) 和振荡电位(oscillatory potentials, OPs)的变化，了解视网膜神经性调控机制对环境照明改变的反应。方法应用自行设计的全视野刺激的ERG记录仪，采用 DTL纤维电极于角膜端记录出生25~29 d Albino鼠(Wistar Fu)眼在暗视及以2个对数单位递增的4个背景光强 度 ——“弱”(1.43×10^-6cd/m²)、“次弱”(1.43×10^-4cd/m²)、“ 次强”(1.43×10^-2cd/m²)和“强”(1.43×10^-2cd/m²)下的ERG a波和b 波。采用数字式滤波器，同时记录OPs。刺激闪光强度为1.43×10^-2cd/m²，闪光时程75 ms，闪光间隔时间1 min 。结果随着背景照明强度的增强，OPs子波数由5个减少至3个，但子波振幅总和增加。当背景光强度增强到最强水平，OPs振幅总和减少。ERG a波和b波振幅在2个弱背景光照明下未见改变。但在强背景照明范围，a波和b波振幅随照明强度的增强而呈下降趋势。结论Albino鼠视网膜内层存在的神经调控系统对环境照明改变的反应比感光细胞更敏感、更快。记录OPs时采用适当的连续背景光照明，可提高反应记录的稳定性。(中华眼底病杂志,2001,17:286-288)

Effect of background light intensity on the slow components and the oscillatory potentials of the electroretinogram

ObjectiveTo study the response of the retinal neuronal adaptive system to changes of background illumination (BG) by measuring the oscillatory potentials (OPs) and the a- and b-waves of the electroretinogram (ERG) in different BG illuminations. MethodsThe a- and b-wave and the digitally filtered OPs were simultaneously recorded from Wistar Fu rats aged from 25 to 29 days during dark adaptation (DA) and during 6~8 minutes of BG illuminations at four levels increased successively by steps of two log units, i.e., “low scotopic” level of 1.43×10^-6cd/m², “high scotopic” of 1.43×10^-4cd/m² , “low mesopic” of 1.43×10^-2cd/m² and “high mesopic” of 1.43×10^-2cd/m². Full field stimulus flashes of 75 msec duration and 1.43×10^-2cd/m²intensity was delivered at an interval of 1 minute. ResultsFive OP wavelets were recorded in DA and during scotopic BG illuminations. The number of wavelets was reduced to three as the eyes were exposed to mesopic BG levels. However, the sum of OPs amplitudes (SOPs) increased as the BG was intensified, except at “high mesopic” level, by which a significant decrease of SOPs occurred. The amplitudes of the a- and b-waves remained unchanged at the two scotopic BG and decreased as the BG intensity increased to mesopic levels. ConclusionThe response of retinal neural adaptive system of the Albino rat to changes of BG light is more sensitive and robust than the slow components of the ERG. The enhancement of the oscillatory responses at “low mesopic” illumination level suggests that using proper BG light may be conducive to reducing the variation of OPs. (Chin J Ocul Fundus Dis, 2001,17:286-288)