Riva C E, Titze P, Hero M, Movaffaghy A, Petrig B L
Institut de Recherche en Ophtalmologie, Sion, Switzerland.
Invest Ophthalmol Vis Sci. 1997 Oct;38(11):2338-43.
To investigate the response of choroidal blood flow in the foveal region of the human eye to increases in mean perfusion pressure (PPm = mean ophthalmic artery pressure - intraocular pressure; IOP) induced by isometric exercises.
Using laser-Doppler flowmetry, changes in velocity (ChBVel), number (ChBVol), and flux (ChBF) of red blood cells in the choroidal vascular system in the foveal region of the fundus were measured in both eyes of 11 normal subjects (ages 18 to 57 years) during isometric exercises.
During 90 seconds of squatting, PPm increased by an average of 67%, from 46 to 77 mm Hg. This resulted in a significant increase of 12% in ChBFm (the mean of ChBF during the heart cycle), mainly caused by an increase in ChBVelm. A further increase in PPm to a value approximately 85% above baseline resulted in a 40% increase in ChBFm. A significant negative correlation was found between the changes in ChBVelm and ChBVolm, during squatting.
Previous studies have demonstrated that during isometric exercise, blood pressures in the ophthalmic and brachial arteries rise in parallel. These observations and the current results indicate that an increase in PPm up to 67% induces an increase in choroidal vascular resistance that limits the increase in choroidal blood flow to approximately 12%. This regulatory process fails when PPm is further increased.
研究等长运动引起的平均灌注压（PPm = 平均眼动脉压 - 眼压；IOP）升高时人眼黄斑区脉络膜血流的反应。
使用激光多普勒血流仪，在11名正常受试者（年龄18至57岁）双眼进行等长运动期间，测量眼底黄斑区脉络膜血管系统中红细胞的速度（ChBVel）、数量（ChBVol）和流量（ChBF）的变化。
在90秒的蹲姿过程中，PPm平均升高67%，从46毫米汞柱升至77毫米汞柱。这导致ChBFm（心动周期中ChBF的平均值）显著增加12%，主要是由ChBVelm增加所致。PPm进一步升高至比基线高约85%的值时，ChBFm增加40%。在蹲姿过程中，发现ChBVelm和ChBVolm的变化之间存在显著负相关。
先前的研究表明，在等长运动期间，眼动脉和肱动脉的血压平行升高。这些观察结果和当前结果表明，PPm升高至67%会导致脉络膜血管阻力增加，从而将脉络膜血流的增加限制在约12%。当PPm进一步升高时，这种调节过程失效。
