Cideciyan A V, Jacobson S G
Department of Ophthalmology, University of Miami School of Medicine, Bascom Palmer Eye Institute, FL 33136.
Invest Ophthalmol Vis Sci. 1993 Nov;34(12):3253-63.
Patients with typical clinical features of retinitis pigmentosa were found to have the atypical electroretinographic finding of a negative waveform to a bright flash in the dark-adapted state. The full-field electroretinogram (ERG) was studied in seven such patients to understand better the pathophysiology.
Rod ERGs were isolated using blue and red flash stimuli in the dark-adapted state. The rod ERG was assumed to be the sum of two major components, P3 and P2. A family of delayed Gaussian functions fitted to the rod a-wave intensity series was used to estimate the P3 component. The P2 component was derived by subtracting the estimated P3 component from the rod-isolated ERG. Long duration stimuli were used to elicit "on" and "off" components of the light-adapted cone ERG. Oscillatory potentials were isolated by digitally filtering cone ERGs to white flash stimuli.
The estimated rod P3 component was reduced in amplitude in all patients. The derived P2 component of the rod ERG was present but abnormally reduced relative to the P3 component. Cone waveforms had decreased a-waves, "on" and "off" components. Many of the patients had a disproportionate reduction of the "on" compared to the "off" component. Photopic oscillatory potentials were either reduced in amplitude and delayed in timing or not detectable.
The ERG findings in this subset of RP patients indicate there is dysfunction not only at the level of the photoreceptor outer segment but also at or proximal to the photoreceptor terminal region.
发现具有典型视网膜色素变性临床特征的患者在暗适应状态下对明亮闪光有非典型的视网膜电图阴性波形。对7例此类患者进行了全视野视网膜电图（ERG）研究，以更好地了解其病理生理学。
在暗适应状态下使用蓝色和红色闪光刺激分离视杆细胞ERG。视杆细胞ERG被认为是两个主要成分P3和P2的总和。用一族拟合视杆细胞a波强度系列的延迟高斯函数来估计P3成分。P2成分是通过从视杆细胞分离的ERG中减去估计的P3成分得到的。使用长时间刺激来引出明适应视锥细胞ERG的“开”和“关”成分。通过对视锥细胞ERG进行数字滤波以获得对白色闪光刺激的振荡电位。
所有患者视杆细胞P3成分的估计幅度均降低。视杆细胞ERG的派生P2成分存在，但相对于P3成分异常减少。视锥细胞波形的a波、“开”和“关”成分均降低。许多患者的“开”成分相对于“关”成分减少不成比例。明视振荡电位幅度降低且时间延迟或无法检测到。
这一亚组视网膜色素变性患者的ERG结果表明，不仅在光感受器外段水平存在功能障碍，而且在光感受器终末区域或其近端也存在功能障碍。
