背景光在局部视网膜电图中作用的研究

The study of background light effect to the focal electroretinogram

目的测定不同背景光强度下的局部视网膜电图的振幅及黄斑／视盘振幅比，研究它们的变化，评价背景光强度在局部视网膜电图中的作用。方法对１８例（２０眼）正常人进行不同背景光强度下的局部视网膜电图的测定，背景光强度依次为２５，５０，１００，１５０，２５０，６００ｃｄ／ｍ２．分别记录刺激黄斑及视盘的反应。将波形进行Ｆｏｕｒｉｅｒ分析，测量刺激频率的基波振幅，计算黄斑／视盘振幅比。结果在２５，５０ｃｄ／ｍ２的背景光下，局部视网膜电图的基波振幅最大（ｘ＝１．６６±０．８５９），黄斑／视盘振幅比最小（ｒ＝１．４６９）。在１００ｃｄ／ｍ２的背景光强度下，局部视网膜电图的基波振幅较大（ｘ＝１．１８５±０．１８１），而黄斑／视盘振幅比达到最大（ｒ＝３．９５）。当背景光继续增加时（２５０，６００ｃｄ／ｍ２），局部视网膜电图的基波振幅最小（ｘ＝０．４１６±０．１４６），黄斑／视盘振幅比则较小（ｒ＝２．２７）。结论背景光较弱时，记录的电反应包含了刺激光斑在眼内弥散后刺激视网膜其它部位而产生的电活动，反应振幅大，但黄斑／视盘的振幅比小，局部视网膜电图的精确性差；背景光过强时。视网膜遭到漂白，视网膜敏感度降低，记录的电反应振幅小，黄斑／视盘?

Objective Record the amplitude of the macula and the optic disc and its ratio of the focal electroretinogram under the different light intensity of background,and evaluate the light intensity of background effect to the focal electroretinogram. Methods Under the light intensity of background were 25cd/m2, 50 cd/m2. 100cd/m2. 150cd/m2, 250cd/m2. 600cd/m2, 20 eyes of 18 normal persons were examined to record the responses of the macula and the optic disc of the foacl electroretinogram. The amplitude of the basic wave of the focal electroretinogram under certain frequency was obtained by the Fourier Analysis, The amplitude ratio of the macula and the optic disc was calculated. Results Under the light intensity of background were 25cd/m2, 50cd/m2,the amplitude of the basic wave of the focal electroretinogram was the largest, but the amplitude ratio of the macula and the optic disc was the least. Under the light intensity of background is 100 cd/m2 , the amplitude was larger, but the ratio was largest. When the light intensity of background was increasing, the amplitude and the ratio became smaller. Conclusion When the intensity of the background light was a little larger than that of the irritation light, the amplitude was larger and the ratio was largest. At that light intensity of background the focal electroretinogram accurately reflects the function of the macula.