Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, 1855 W. Taylor St., MC/648, Chicago, IL, 60612, USA.
Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan St., Chicago, IL, 60607, USA.
Doc Ophthalmol. 2023 Jun;146(3):229-239. doi: 10.1007/s10633-023-09925-y. Epub 2023 Feb 10.
To infer rod phototransduction activation and deactivation characteristics in diabetics who have mild or no clinically-apparent retinopathy.
Fifteen non-diabetic controls, 15 diabetics with no clinically-apparent diabetic retinopathy (NDR), and 15 diabetics with mild non-proliferative diabetic retinopathy (MDR) participated. Dark-adapted flash electroretinograms (3.2 to 4.4 log scot td-s) were recorded to assess rod activation. The a-waves were fit with a Gaussian model to derive R (maximum photoreceptor response amplitude) and S (phototransduction sensitivity). Rod deactivation was assessed with a paired flash paradigm, in which a-waves were measured for two flashes separated by inter-stimulus intervals (ISIs) of 0.125 to 16 s. The ISI needed for the a-wave amplitude of the second flash to recover to 50% of the first flash (t) was determined. The effect of stimulus retinal illuminance on activation and deactivation was evaluated in a subset of control subjects.
Analysis of variance indicated that both diabetic groups had significant log S reductions compared to controls (p < 0.001). Mean S was reduced by approximately 49% and 78% for the NDR and MDR groups, respectively. In contrast, log R and log t did not differ significantly among the groups (both p > 0.08). Reducing stimulus retinal illuminance significantly reduced S, but did not significantly affect R or t.
Only phototransduction sensitivity was abnormal in this sample of diabetic subjects. The normal deactivation kinetics suggests that circulating rod current is normal. These findings begin to constrain possible explanations for abnormal rod function in early diabetic retinal disease.
推断轻度或无临床明显视网膜病变的糖尿病患者的视杆光转导激活和失活特征。
15 名非糖尿病对照者、15 名无临床明显糖尿病视网膜病变（NDR）的糖尿病患者和 15 名轻度非增殖性糖尿病视网膜病变（MDR）的糖尿病患者参与了研究。记录暗适应闪光视网膜电图（3.2 至 4.4 log scot td-s）以评估视杆激活。使用高斯模型拟合 a 波，以得出 R（最大光感受器反应幅度）和 S（光转导灵敏度）。通过双闪光范式评估视杆失活，在该范式中，在两个刺激之间的刺激间隔（ISI）为 0.125 至 16 s 的情况下测量 a 波。确定第二个闪光的 a 波幅度恢复到第一个闪光的 50%（t）所需的 ISI。在一组对照受试者中评估了刺激视网膜照度对视杆激活和失活的影响。
方差分析表明，与对照组相比，两组糖尿病患者的 log S 均显著降低（p < 0.001）。NDR 和 MDR 组的平均 S 分别降低了约 49%和 78%。相比之下，log R 和 log t 在各组之间没有显著差异（均 p > 0.08）。降低刺激视网膜照度显著降低了 S，但对 R 或 t 没有显著影响。
在这个糖尿病患者样本中，只有光转导灵敏度异常。正常的失活动力学表明循环视杆电流正常。这些发现开始限制早期糖尿病视网膜病变中视杆功能异常的可能解释。
