VEP Profile of Various Contrasts and Spatial Frequencies

各種對比及空間頻率之視覺誘發電位

王藹侯(Ai-Hou Wang) ； 張志豪(Ji-Hau Jan) ； 柯良時(Liang-Shi Ko)

《中華民國眼科醫學會會刊》 29卷1期 (1990/05) Pp. 495-501

https://doi.org/10.30048/ACTASOS.199005.0083

摘要

視覺誘發電位是估計語前兒童視力的方法之一；將對比感度曲線高頻部分作外插法，亦可得到視力的估計值。我們將這兩個觀念結合，以各種不同對比及空間頻率之西洋棋盤圖樣為刺激，所得到的誘發電位波幅作圖，可畫出“形態視覺”的輪廓。
在IBM VGA單色螢幕上，我們選擇方格邊長為100，50，25，12和6分角五種空間頻率；對每種空間頻率，選擇0.96，0.48，0.24，0.12和0.06五種對比，其平均亮度置於50cd/平方公尺。
對暫態誘發電位，我們以P1-N2波幅作圖；對穩態誘發電位，則以峰谷波幅作圖。
每一眼僅25次的誘發電位，要描繪出形態視覺的輪廓仍嫌太少。但以傳統的平均法消除雜訊，每一眼做25次誘發電位，大約需要半個小時，對病人和醫生都難免不耐。而在幼兒及兒童，長時間記錄的不穩定及不可重覆性，使得平均法全無用武之地。掃掠誘發電位以符立葉法去除雜訊，正是解決此一障礙的良方。

並列摘要

Pattern visual evoked potential is one of the standard method to get the visual acuity in preverbal children. Extrapolation of contrast sensitivity curve at high spatial frequency also gets estimated visual acuity. Combining these two figures, we will get the VEP profile of form vision. With the IBM VGA monochrome monitor, we generated checkerboard of various spatial frequencies and contrasts. We chose five sizes: 100, 50, 25, 12 and 6 mm-arc and five contrasts: 0.96, 0.48, 0.24, 0.12 and 0.06 with mean luminance of 50 cd/sq.m, totally 25 stimuli to record VEPs. For transient VEPs, we measured P1-N2 amplitudes and for steady state VEPs, we measured peak to peak amplitudes to put them into 3 dimensional graphics for clear illustration of the form vision profile. Using conventional average method, 25 recordings for one eye took about half hour. It was boring both for patient and doctor and inpractical in incooperated children. Sweep method will throw new perspective to this problem.

並列關鍵字

form vision ； visual evoked potential VEP ； contrast ； spatial frequency