Creel Donnell J
John A. Moran Eye Center, University of Utah, USA.
J Vis Exp. 2011 Dec 4(58):3176. doi: 10.3791/3176.
A limitation of traditional full-field electroretinograms (ERG) for the diagnosis of retinopathy is lack of sensitivity. Generally, ERG results are normal unless more than approximately 20% of the retina is affected. In practical terms, a patient might be legally blind as a result of macular degeneration or other scotomas and still appear normal, according to traditional full field ERG. An important development in ERGs is the multifocal ERG (mfERG). Erich Sutter adapted the mathematical sequences called binary m-sequences enabling the isolation from a single electrical signal an electroretinogram representing less than each square millimeter of retina in response to a visual stimulus. Results that are generated by mfERG appear similar to those generated by flash ERG. In contrast to flash ERG, which best generates data appropriate for whole-eye disorders. The basic mfERG result is based on the calculated mathematical average of an approximation of the positive deflection component of traditional ERG response, known as the b-wave. Multifocal ERG programs measure electrical activity from more than a hundred retinal areas per eye, in a few minutes. The enhanced spatial resolution enables scotomas and retinal dysfunction to be mapped and quantified. In the protocol below, we describe the recording of mfERGs using a bipolar speculum contact lens. Components of mfERG systems vary between manufacturers. For the presentation of visible stimulus, some suitable CRT monitors are available but most systems have adopted the use of flat-panel liquid crystal displays (LCD). The visual stimuli depicted here, were produced by a LCD microdisplay subtending 35-40 degrees horizontally and 30-35 degrees vertically of visual field, and calibrated to produce multifocal flash intensities of 2.7 cd s m(-2). Amplification was 50K. Lower and upper bandpass limits were 10 and 300 Hz. The software packages used were VERIS versions 5 and 6.
传统的全视野视网膜电图（ERG）用于视网膜病变诊断的一个局限性是缺乏敏感性。一般来说，除非视网膜受影响的面积超过约20%，ERG结果通常是正常的。实际上，根据传统全视野ERG，患者可能因黄斑变性或其他暗点而法定失明，但ERG结果仍显示正常。ERG的一项重要进展是多焦ERG（mfERG）。埃里希·萨特采用了称为二进制m序列的数学序列，使得能够从单个电信号中分离出代表小于每平方毫米视网膜对视觉刺激反应的视网膜电图。mfERG产生的结果与闪光ERG产生的结果相似。与最适合生成全眼疾病相关数据的闪光ERG不同，基本的mfERG结果基于传统ERG反应正性偏转成分（即b波）近似值的计算数学平均值。多焦ERG程序可在几分钟内测量每只眼睛一百多个视网膜区域的电活动。增强的空间分辨率使暗点和视网膜功能障碍能够被定位和量化。在以下方案中，我们描述了使用双极窥镜接触镜记录mfERG的方法。mfERG系统的组件因制造商而异。对于可见刺激的呈现，有一些合适的阴极射线管显示器可供使用，但大多数系统已采用平板液晶显示器（LCD）。此处描绘的视觉刺激由一个LCD微型显示器产生，该显示器在水平方向上对视角为35 - 40度，在垂直方向上对视角为30 - 35度，并经过校准以产生2.7 cd s m(-2)的多焦闪光强度。放大倍数为50K。下限和上限带通频率分别为10和300 Hz。使用的软件包是VERIS版本5和6。
