Bijveld Mieke M C, Kappers Astrid M L, Riemslag Frans C C, Hoeben Frank P, Vrijling Anne C L, van Genderen Maria M
Bartiméus, Institute for the Visually Impaired, PO Box 1300, 3700 BA, Zeist, The Netherlands.
Doc Ophthalmol. 2011 Dec;123(3):149-59. doi: 10.1007/s10633-011-9292-z. Epub 2011 Sep 24.
The minimum in the amplitude versus flash strength curve of dark-adapted 15 Hz electroretinograms (ERGs) has been attributed to interactions between the primary and secondary rod pathways. The 15 Hz ERGs can be used to examine the two rod pathways in patients. However, previous studies suggested that the cone-driven pathway also contributes to the 15 Hz ERGs for flash strengths just above that of the minimum. We investigated cone pathway contributions to improve upon the interpretation of (abnormal) 15 Hz ERGs measured in patients. We recorded 15 Hz ERGs in five healthy volunteers, using a range of flash strengths that we extended to high values. The stimuli were varied in both colour (blue, green, amber, and red) and flash duration (short flash and square wave) in order to stimulate rods and cones in various ways. The differences in the responses to the four colours could be fully explained by the spectral sensitivity of rods for flash strengths up to approximately 12.5 log quanta·deg(-2). At higher flash strengths, higher-order harmonics appeared in the responses which could be attributed to cones being more sensitive than rods to higher frequencies. Furthermore, the amplitude curves of the blue and green responses showed a second minimum suggesting rod to cone interactions. We present a descriptive model of the contributions of the rod and cone pathways. In clinical application, we would advise using the short flash flicker instead of the square wave flicker, as the responses are of larger amplitude, and cone pathway contributions can be recognized from large higher-order harmonics.
暗适应15Hz视网膜电图（ERG）的振幅与闪光强度曲线中的最小值被认为是初级和次级视杆通路之间相互作用的结果。15Hz ERG可用于检查患者的两条视杆通路。然而，先前的研究表明，对于略高于最小值强度的闪光，视锥驱动通路也会对15Hz ERG产生影响。我们研究了视锥通路的影响，以改进对患者测量的（异常）15Hz ERG的解读。我们记录了5名健康志愿者的15Hz ERG，使用了一系列扩展到高值的闪光强度。刺激在颜色（蓝色、绿色、琥珀色和红色）和闪光持续时间（短闪光和方波）方面都有所变化，以便以各种方式刺激视杆和视锥。对于高达约12.5 log量子·度（-2）的闪光强度，对四种颜色反应的差异可以完全由视杆的光谱敏感性来解释。在更高的闪光强度下，反应中出现了高阶谐波，这可归因于视锥比视杆对更高频率更敏感。此外，蓝色和绿色反应的振幅曲线显示出第二个最小值，表明存在视杆到视锥的相互作用。我们提出了一个视杆和视锥通路贡献的描述性模型。在临床应用中，我们建议使用短闪光闪烁而不是方波闪烁，因为反应的振幅更大，并且可以从大的高阶谐波中识别出视锥通路的贡献。
