Different autoregulation response to dynamic exercise in ophthalmic and central retinal arteries: a color Doppler study in healthy subjects

Abstract

Our results confirm the presence of an effective compensatory autoregulation for the retinal circulation, in connection with an increase in the ocular perfusion pressure induced by exercise. However, we found that in the ophthalmic artery some over-compensation occurs (significant decrease in some velocity parameters), whereas in the central retinal artery important flow parameters (mean velocity, end-diastolic velocity and resistive indices) appear to be successfully stabilized. Exercise history, heart rate, blood pressure and intraocular pressure all have to be monitored in orbital blood flow studies, as these variables are strongly affected by the changes in the autonomic nervous system and in turn significantly influence the measured flow velocity and resistivity values.

Effects of dynamic exercise and its intensity on ocular blood flow in humans

“…This difference may be attributable to differences in the characteristics of the target vessel, exercise intensity, and the timing of the observations. Exercise exerted no significant effects on the arterioles in the present study, a finding that concurs with the similar findings of some previous studies that investigated the ophthalmic and central retinal arteries (Michelson et al 1994;Németh et al 2002). Thus, it appears that the blood flow in the ocular arteries and arterioles is unlikely to be altered by light-to moderateintensity exercise.…”

“…Thus, it appears that the blood flow in the ocular arteries and arterioles is unlikely to be altered by light-to moderateintensity exercise. The intensity of exercise was much higher in the present study than in previous studies: HR was doubled in the present study, but it increased by only around 50% in previous studies (Forcier et al 1998;Harris et al 1996;Iester et al 2007;Michelson et al 1994;Németh et al 2002;Okuno et al 2006). Moreover, these previous studies obtained data after, and not during, exercise; in the present study, the changes in ocular blood flow observed in the RCV had disappeared within 3 min of recovery.…”

“…However, there is little evidence to support this conclusion, since all but one (Lovasik et al 2003) of those previous studies included in the review article (Forcier et al 1998;Harris et al 1996;Iester et al 2007;Michelson et al 1994;Németh et al 2002;Okuno et al 2006) measured blood flow after, rather than during exercise. Data obtained after exercise cessation do not reflect the ocular blood flow during exercise, since the circulation recovers rapidly thereafter-the choroidal flow has been reported to decrease by about 12% per minute during the initial 4 min of exercise recovery (Lovasik et al 2003).…”

Ocular blood flow measurements in healthy human myopic eyes

“…Thus, similar vascular features shared by myopia and glaucoma may help to explain the association between the two conditions [35], this being of particular clinical importance with respect to the reported increasing prevalence of myopia, which has now reached epidemic levels [39]. The ocular autoregulatory properties of the healthy and glaucomatous eye have been described previously [40][41][42]; however, they were not evaluated in the present study, and remain unexplored in the myopic eye. Therefore, the altered ocular circulation as a cause or consequence of myopia and as a risk factor for co-morbidity with other ocular diseases such as glaucoma remains equivocal.…”

The effect of physical effort on retinal activity in the human eye: rod and cone flicker electroretinogram studies

“…During exercise, normal blood flow in the retina is maintained by autoregulation of perfusion [9,10]. Studies [11,12] show that physical exercise decreases the diameter of large retinal arteries and alters retinal vein diameters.…”