Hafner Julia, Ginner Laurin, Karst Sonja, Leitgeb Rainer, Unterluggauer Michael, Sacu Stefan, Mitsch Christoph, Scholda Christoph, Pablik Eleonore, Schmidt-Erfurth Ursula
Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.
Center of Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
Invest Ophthalmol Vis Sci. 2017 Oct 1;58(12):5541-5547. doi: 10.1167/iovs.17-22523.
Alterations in retinal oxygen metabolism and retinal microcirculation are signs of impending diabetic retinopathy (DR). However, if specific retinal regions are primarily affected is so far unknown. The purpose of this study was to investigate if retinal oxygen saturation (SO2) and microvascular hemodynamic parameters follow a distinct regional pattern in patients with diabetes but no DR.
Patients with type II diabetes without clinically apparent DR were imaged as follows: SO2 in peripapillary vessels was assessed with dual-wavelength oximetry. Optical coherence tomography angiography (OCTA) scans were acquired with a prototype system using a swept-source laser with an effective 400 kHz A-scan rate and 16° field of view. Regional flow indices termed "flux" were calculated for the peripapillary microvasculature. Parafoveal capillary density was evaluated with the commercially available AngioVue OCTA.
Twenty-nine eyes of 16 consecutive patients (59 ± 10 years, 6 females) were included in this study. SO2 differed significantly between quadrants (P < 0.001), with a decreasing pattern from the upper nasal through the lower nasal, the upper temporal and the lower temporal quadrant in arterioles and venules. In contrast, peripapillary flux followed an increasing trend from nasally to temporally. Peripapillary and parafoveal microvascular hemodynamic parameters demonstrated no significant regional variability as observed for retinal oxygenation.
Metabolic imaging identified regional differences in retinal SO2 without an associated topographic variance in microvascular hemodynamics in type II diabetes without DR. Future studies should focus on the mechanisms causing this heterogeneity in metabolic demand.
视网膜氧代谢和视网膜微循环的改变是糖尿病视网膜病变（DR）即将发生的迹象。然而，目前尚不清楚特定的视网膜区域是否受到主要影响。本研究的目的是调查糖尿病但无DR患者的视网膜氧饱和度（SO2）和微血管血流动力学参数是否遵循不同的区域模式。
对无临床明显DR的II型糖尿病患者进行如下成像：用双波长血氧测定法评估视乳头周围血管的SO2。使用具有有效400kHz A扫描速率和16°视野的扫频源激光的原型系统进行光学相干断层扫描血管造影（OCTA）扫描。对视乳头周围微血管计算称为“通量”的区域血流指数。用市售的AngioVue OCTA评估黄斑旁毛细血管密度。
本研究纳入了16例连续患者（59±10岁，6名女性）的29只眼。象限间SO2差异有统计学意义（P<0.001），在小动脉和小静脉中，从鼻上象限经鼻下象限、颞上象限和颞下象限呈下降趋势。相比之下，视乳头周围通量从鼻侧到颞侧呈增加趋势。视乳头周围和黄斑旁微血管血流动力学参数未显示出如视网膜氧合那样明显的区域变异性。
代谢成像发现II型糖尿病无DR患者视网膜SO2存在区域差异，但微血管血流动力学无相关的地形差异。未来的研究应关注导致这种代谢需求异质性的机制。
