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Invest Ophthalmol Vis Sci. 2020 Feb 7;61(2):33. doi: 10.1167/iovs.61.2.33.
Blood flow autoregulation is an intrinsic mechanism of the healthy retinal vasculature to keep blood flow constant when ocular perfusion pressure (OPP) is changed. In the present study, we set out to investigate retinal blood flow in response to an experimental decrease in OPP in healthy participants using Doppler optical coherence tomography.
Fifteen healthy participants aged between 22 and 31 years (mean, 27 ± 3 years) were included in the present open study. IOP was increased stepwise via the suction cup method to induce a decrease in OPP. Retinal blood flow in arteries and veins was assessed using a custom-built Doppler optical coherence tomography system and pressure-flow relationships were calculated to assess autoregulation.
Suction cup application induced a pronounced increase in IOP with a maximum value of 50.5 ± 8.0 mm Hg at the highest level of suction. Pressure-flow relationships revealed that blood flow was autoregulated until the OPP was decreased by approximately 21 mm Hg and started to decrease significantly when the OPP was reduced by 30 mm Hg. Retinal blood flow at the last suction period decreased at a maximum of -57.0 ± 22.3% and 65.2 ± 15.4% in retinal arteries and retinal veins, respectively. These changes in retinal blood flow were less pronounced than the decrease in OPP (-75.2 ± 19.2%), indicating retinal autoregulation.
The results of the present study confirm that retinal blood flow is autoregulated in response to changes in the OPP. Doppler optical coherence tomography has the potential to become a clinical tool for the investigation of retinal blood flow autoregulation in the future, because of its ability to assess the blood velocities and diameter of the retinal vessels parallel and therefore also their blood flow in absolute values. (Clinicaltrials.gov number NCT03398616).
血液流动自动调节是健康视网膜血管的内在机制，可在眼灌注压（OPP）改变时保持血流恒定。在本研究中，我们使用多普勒光相干断层扫描（OCT）研究健康参与者在 OPP 降低时视网膜血流的变化，以探索自动调节机制。
本开放性研究共纳入 15 名年龄在 22 岁至 31 岁之间（平均 27 ± 3 岁）的健康参与者。通过吸盘法逐步升高眼压（IOP）以诱导 OPP 降低。使用定制的多普勒 OCT 系统评估动脉和静脉的视网膜血流，并计算压力-血流关系以评估自动调节。
吸盘应用可显著增加 IOP，在最高吸力水平时最大眼压为 50.5 ± 8.0mmHg。压力-血流关系表明，在 OPP 降低约 21mmHg 之前，血流自动调节，当 OPP 降低 30mmHg 时，血流开始显著降低。在最后一次吸盘阶段，视网膜动脉和视网膜静脉的血流分别最大降低了-57.0 ± 22.3%和 65.2 ± 15.4%。这些视网膜血流的变化不如 OPP 降低显著（-75.2 ± 19.2%），表明存在视网膜自动调节。
本研究结果证实，视网膜血流在 OPP 变化时可自动调节。由于多普勒 OCT 能够平行评估视网膜血管的血流速度和直径，从而可获得绝对血流值，因此它具有成为未来评估视网膜血流自动调节的临床工具的潜力。（Clinicaltrials.gov 编号：NCT03398616）
