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Vasomotor reaction of retinal arterioles in hypoxic and ischemic conditions
Author(s) -
POURNARAS CJ
Publication year - 2012
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2012.4414.x
Subject(s) - retinal , retina , medicine , hypoxia (environmental) , microcirculation , blood flow , perfusion , diabetic retinopathy , vasoconstriction , hyperoxia , ophthalmology , diabetes mellitus , endocrinology , biology , neuroscience , chemistry , organic chemistry , lung , oxygen
Purpose Retinal blood flow is autoregulated by the adaptation of the vascular tone of resistance vessels (arterioles, capillaries) to changes in the perfusion pressure (PP) or metabolic needs of the tissue. The purpose of this study was to evaluate the disturbance of arteriolar reactivity, and thus of blood flow regulation, during the evolution of ischemic retinal microangiopathies. Methods Much of our basic knowledge of retinal arteriolar reactivity is based on data obtained from animal experiments through the use of invasive techniques. However, a variety of non‐invasive techniques has been applied to the human eye for the investigation of retinal hemo‐dynamics and, more specifically, the reactivity of the retinal arterioles in response to a number of physiologic and pharmacologic stimuli, under normal, hypoxic and ischemic conditions. Results In patients with non‐proliferative diabetic retinopathy (DR), isocapnic hypoxia induces a significant increase in Vleuk in the perifoveal circulation, whereas in patients with proliferative DR, the diameter of the retinal vessels remains unchanged, indicating that blood flow regulation in response to a hypoxic challenge is blunted,consequent to the hypoxic retinal conditions. In those patients a hyperoxia‐induced blunted vasoconstriction of the retinal arterioles is also observed. The ability of the retinal arterioles to respond to changes in ocular PP is altered in diabetes, while the response of retinal vessels to diffuse luminance flicker is blunted, particularly in patients suffering from insulin‐dependent diabetes. Conclusion During the evolution of retinal ischemic microangiopathies, impairment of various mechanisms of retinal arteriolar reactivity leads to disturbed retinal blood flow regulation.