Abstract
Purpose :
A recent study has shown that an increase in the arterial blood pressure leads to constriction of retinal arterioles that is sufficient to maintain constant blood flow in the macular area, but not in the retinal periphery where the blood flow is increased. However, it is unknown whether hypoxia-induced vasodilatation in the retina shows similar regional differences.
Methods :
In five of 30 scheduled examinations in healthy young individuals, oxygen saturation, vessel diameter, and blood flow were measured in the upper temporal peripapillary arteriole, and in branches from this vessel towards respectively the macular area and the retinal periphery. The measurements were performed before and during breathing of a hypoxic gas mixture containing 12.5% oxygen.
Results :
Hypoxia significantly reduced the systemic oxygen saturation from (mean±SD) 97.4% ± 0.9% to 86.2% ± 3.0% (p<0.001), and the saturation of the studied arterioles from 94.1% ± 5.1% to 85.8% ± 6.6% (p<0.001). There were no significant differences between the increase in vessel diameter (21.5% ± 13.7%, 18.2% ± 27.0%, and 15.3% ± 17.6%) (p=0.89) and the increase in blood flow (67.0% ± 46.3%, 30.5% ± 90.3%, and 98.5% ± 112.0%) (p=0.53), in respectively peripapillary, peripheral and macular arterioles during hypoxia.
Conclusions :
The preliminary results suggest that systemic hypoxia induces similar vasodilation and hyperperfusion in the peripapillary, peripheral and macular arterioles. This argues against regional differences in the vascular response to hypoxia as an explanation to the different pattern of lesions in the macular area and the retinal periphery in retinal vascular disease.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.