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Gabriele Fuchsjaeger-Mayrl, Gerhard Garhofer, Leopold Schmetterer; Retinal Blood Flow And Systemic Blood Pressure In Healthy Subjects. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6054.
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Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. A variety of studies using interventions to modify either blood pressure or intraocular pressure indicate that retinal blood flow is autoregulated over a wide range of ocular perfusion pressures. Another way of proofing autoregulation is to correlate group data, which was done in the present study.
In the present study 64 healthy subjects aged between 18 and 45 years were included. Bi-directional laser Doppler velocimetry (Oculix, Arbaz, Switzerland) was used to measure retinal blood velocities. Venous vessel diameters were measured using the Retinal Vessel Analyzer (Imedos, Jena, Germany). Retinal blood flow was calculated by measuring all visible veins entering the optic nerve head. Ocular perfusion pressure was calculated as 2/3 mean arterial pressure minus intraocular pressure.
Retinal blood flow was 46.2 ± 7.4 ml/min. Ocular perfusion pressure was 49.3 ± 3.6 mmHg. There was no significant association between retinal blood flow and ocular perfusion pressure (r = 0.04, p > 0.05).
The data from the present study indicate that retinal blood flow is well regulated in healthy subjects. This confirms previous data using interventions such as isometric exercise or artificial intraocular pressure increase. Studying group correlations between retinal blood flow and ocular perfusion pressure may be an attractive approach to gain insight into abnormal autoregulation in vascular disease.
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