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H. Kergoat, J. V. Lovasik, N. Racine, M.-J. Kergoat, M. Parent; Enhanced Retinal Perfusion Ability in Long-Term Marathoners. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2082.
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Last year we reported that flicker-induced retinal vessel dilation was smaller in marathoners than in controls. We hypothesized that the vascular system in runners responded more efficiently to a flicker-induced increase in retinal metabolism, possibly due to a nitric oxide (NO)-induced increase in basal retinal vessel caliber. We now report our findings on extensive measurements of vessel diameters in the same cohort of runners and controls to validate our earlier hypothesis.
Adult marathoners (n=10) and controls (n=10) matched for age and ocular perfusion pressure volunteered for this study. A digital color fundus photograph was taken for each subject through dilated pupils by the same examiner. A blinded technician measured vessel calibers for paired arteries and veins in the superior and inferior quadrants using a Vessel Map program (Imedos.de). Vessel diameters were measured from the optic nerve head (ONH) outwards to a standard length of 2700microm. Relative vessel diameters were group averaged within subject groups and fundus sites. Data were also normalized for comparisons of vessel thickness profiles (ANOVA p=<0.05).
The group averaged thickness values revealed a biphasic profile over 2700microm. For runners, there was a steep increase in vessel diameter in the first 600microm followed by a monotonic tapering to the vessel end. The control group showed a more monophasic vessel taper outwards from the ONH. The group averaged diameters for all arteries (87.7 +/- 2.9microm vs 80.3 +/- 1.8microm) and veins (93.8 +/- 3.4microm vs 88.2 +/- 1.6microm) combined were larger in the runners (p=0.0001). Furthermore, the arterial diameter in the superior (p=0.0376) and inferior (p=0.0029) quadrants was larger in the runners, as were the A/V ratios in the inferior (p=0.0216) and superior (p=0.0104) quadrants.
Because long-term runners develop a higher chronic concentration of NO in their bloodstream, retinal vessels effectively develop a greater capacity than non-runners to rapidly perfuse retinal tissue as when the retina is abruptly exposed to flicker.
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