Based on clinical findings, diabetic retinopathy (DR) has traditionally been defined as a retinal microvasculopathy. Retinal neuronal dysfunction is now recognized as an early event in the diabetic retina before development of overt DR. While detrimental effects of diabetes on the survival and function of inner retinal cells, such as retinal ganglion cells and amacrine cells, are widely recognized, evidence that photoreceptors in the outer retina undergo early alterations in diabetes has emerged more recently. We review data from preclinical and clinical studies demonstrating a conserved reduction of electrophysiological function in diabetic retinas, as well as evidence for photoreceptor loss. Complementing in vivo studies, we discuss the ex vivo electroretinography technique as a useful method to investigate photoreceptor function in isolated retinas from diabetic animal models. Finally, we consider the possibility that early photoreceptor pathology contributes to the progression of DR, and discuss possible mechanisms of photoreceptor damage in the diabetic retina, such as enhanced production of reactive oxygen species and other inflammatory factors whose detrimental effects may be augmented by phototransduction.

中文翻译：

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糖尿病光感受器：结构和功能变化的机制

根据临床发现，糖尿病视网膜病变 (DR) 传统上被定义为视网膜微血管病变。视网膜神经元功能障碍现在被认为是糖尿病视网膜发生明显 DR 之前的早期事件。虽然糖尿病对视网膜神经节细胞和无长突细胞等视网膜内细胞（如视网膜神经节细胞和无长突细胞）的存活和功能的不利影响已得到广泛认可，但最近出现了外层视网膜中的光感受器在糖尿病中发生早期改变的证据。我们回顾了来自临床前和临床研究的数据，这些数据证明了糖尿病视网膜电生理功能的保守降低，以及光感受器丧失的证据。互补体内研究，我们讨论离体视网膜电图技术作为一种有用的方法来研究从糖尿病动物模型分离的视网膜中的光感受器功能。最后，我们考虑了早期光感受器病理学有助于 DR 进展的可能性，并讨论了糖尿病视网膜中光感受器损伤的可能机制，例如活性氧和其他炎症因子的产生增加，其有害影响可能通过光转导增强。