Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong, SAR, China.
Graefes Arch Clin Exp Ophthalmol. 2010 Aug;248(8):1117-25. doi: 10.1007/s00417-010-1346-5. Epub 2010 Mar 20.
This study aims to ascertain the characteristics of the response triggered by the global flash multifocal electroretinogram (MOFO mfERG) under various combinations of global and focal flash luminance, and to determine the optimal conditions for this measurement.
Ten normal subjects with mean age 23.2 yrs (+/- 1.14 yrs) were recruited for the MOFO mfERG measurement. The visual stimulation consisted of four video frames (stimulus frame with 103 scaled hexagonal focal flashes, followed by a dark frame, a global flash and then another dark frame). The focal and global flash intensities were varied independently for four levels (50, 100, 200 and 400 cd/m(2)). The subjects then underwent measurements with sixteen combinations of focal and global flash luminance. The direct component (DC) and induced component (IC) of the MOFO mfERG were grouped into central and peripheral regions for analysis.
The central and peripheral DC amplitude increased with the focal flash luminance under constant global flash luminance. Moreover, the proportion of the global flash and focal flash intensity was shown to be important to achieve an optimal IC response. When the ratio of global flash luminance to focal flash luminance (g/f ratio) was kept at about 2:1, the central and peripheral IC amplitude reached the peak value, and further increasing the global flash luminance would not enhance the IC response magnitude. The implicit time of both central and peripheral DC generally decreased with the increase of g/f ratio. However, the implicit time of central and peripheral IC increased with the g/f ratio.
The g/f ratio is important in the MOFO mfERG paradigm, since the DC and IC responses change with this ratio. In order to obtain both optimal DC and IC responses, a g/f ratio of 1:1 with focal flash luminance between 100 cd/m(2) and 200 cd/m(2) would be recommended. As the global flash mfERG paradigm is studying the interaction triggered by both flashes, the g/f ratio is a vital parameter for measurement in future studies.
本研究旨在确定在不同的全局闪光和局域闪光亮度组合下，全局闪烁多焦视网膜电图（MOFO mfERG）所引发的反应特征，并确定该测量的最佳条件。
招募了 10 名平均年龄为 23.2 岁（+/-1.14 岁）的正常受试者进行 MOFO mfERG 测量。视觉刺激由四个视频帧组成（带有 103 个缩放六边形局域闪光的刺激帧，接着是一个暗帧、一个全局闪光和另一个暗帧）。局域和全局闪光强度独立变化为四个级别（50、100、200 和 400 cd/m²）。然后，受试者接受了十六种局域和全局闪光亮度组合的测量。MOFO mfERG 的直接成分（DC）和诱导成分（IC）被分为中央和外周区域进行分析。
在恒定的全局闪光亮度下，中央和外周 DC 振幅随局域闪光亮度增加而增加。此外，全局闪光和局域闪光强度的比例对于获得最佳的 IC 反应很重要。当全局闪光亮度与局域闪光亮度的比值（g/f 比）保持在 2:1 左右时，中央和外周 IC 振幅达到峰值，进一步增加全局闪光亮度不会增强 IC 反应幅度。中央和外周 DC 的潜伏期通常随 g/f 比的增加而降低。然而，中央和外周 IC 的潜伏期随 g/f 比的增加而增加。
g/f 比在 MOFO mfERG 范式中很重要，因为 DC 和 IC 反应随此比值而变化。为了获得最佳的 DC 和 IC 反应，建议使用 100 cd/m² 到 200 cd/m² 之间的局域闪光亮度和 1:1 的 g/f 比。由于全局闪光 mfERG 范式正在研究由两个闪光引发的相互作用，因此 g/f 比是未来研究中测量的一个重要参数。
