Effect of nifedipine on choroidal blood flow regulation during isometric exercise.

Purpose: To determine whether nifedipine, an L-type calcium channel blocker, alters choroidal blood flow (ChBF) regulation during isometric exercise in healthy subjects.

Methods: The study was carried out in a randomized, placebo-controlled, double-masked, two-way crossover design. Fifteen healthy male subjects were randomly assigned to receive either placebo or nifedipine on two different study days.

Comparison of the autoregulatory mechanisms between central retinal artery and posterior ciliary arteries after thigh cuff deflation in healthy subjects.

Purpose: To compare dynamic autoregulation in the central retinal artery (CRA) and the posterior ciliary arteries (PCAs) after a step decrease in systemic blood pressure.

Methods: Ten healthy male young subjects were studied. Flow velocities in retrobulbar vessels and systemic blood pressure were recorded in each subject before, during, and after a step decrease in blood pressure.

Role of adenosine in the control of choroidal blood flow during changes in ocular perfusion pressure.

Purpose: The purpose of the present study was to investigate whether the nucleoside adenosine is involved in the regulatory processes of choroidal blood flow (ChBF) during an experimental decrease in ocular perfusion pressure (OPP).

Methods: In this randomized, double-masked, placebo-controlled, two-way crossover study, 14 subjects received either intravenous adenosine or placebo on two different study days. The suction cup method was used for a stepwise increase in intraocular pressure (IOP).

Effect of the α(2)-adrenoceptor antagonist yohimbine on vascular regulation of the middle cerebral artery and the ophthalmic artery in healthy subjects.

There is evidence that vascular beds distal to the ophthalmic artery (OA) show vasoconstriction in response to a step decrease in systemic blood pressure (BP). The mediators of this response are mostly unidentified. The aim of the current study was to test the hypothesis that α2-adrenoreceptors may contribute to the regulatory process in response to a decrease in BP.

Defective myogenic response to posture change in retinal vessels of well-controlled type 1 diabetic patients with no retinopathy.

Purpose: The current approach to the prevention of diabetic retinopathy relies on intensive anti-diabetes treatment and is only partially successful. A marker of retinopathy risk would enable strategies of surveillance, screening of adjunct drugs, and targeted drug interventions. The authors sought to identify early abnormalities of retinal vessels that are not prevented by the current therapeutic approach.