Acute effect of metipranolol on the retinal circulation

Abstract

Aim-To assess the eVect of topical and systemic application of a adrenergic receptor blocker on retinal haemodynamics. Methods-24 healthy subjects were included in this double masked, randomised, placebo controlled crossover study. Metipranolol, a non-selective adrenergic receptor blocking agent was used as test drug. In all subjects armretina time, arteriovenous passage time, arterial mean dye velocity, the arterial vessel diameters, and capillary flow velocity were quantified from digital video fluorescein angiograms. Results-A significant eVect was observed on the arteriovenous passage time (p<0.05), the arterial mean dye bolus velocity (p<0.05), and capillary blood velocity (p<0.05), but not on the arterial vessel diameter. The arterial mean dye bolus velocity and capillary blood velocity increased after application of the test drug (topical and systemic). In tandem with this a decrease of the arteriovenous passage time was observed. The perfusion pressure increased after topical application and remained unchanged after systemic application of metipranolol. Conclusions-This study shows that systemic as well as topical application of metipranolol leads to increased retinal blood flow velocities. The implications of these results for treatment with adrenergic receptor blockers is not clear. However, in view of these data it is very unlikely that treatment with metipranolol has a negative eVect on retinal blood flow. (Br J Ophthalmol 1998;82:892-896) Recently the eVect of medications used for glaucoma therapy on ocular blood flow has become an area of increased interest.

Topical Drug Therapy in Glaucoma

“…It is available as 0.3 % ophthalmic solution and the recommended dose is one drop twice a day. Metipranolol seems to increase retinal perfusion pressure and retinal blood flow velocities [21], but reduces choroidal and optic disc blood flow [22], which might indicate vasoconstriction.…”

Review of the association between retinal microvascular characteristics and eye disease

“…This is possibly attributed to confounding by significant differences in design and methodology across studies. Some authors have shown no effect of selective or non‐selective beta‐blockers on vessel diameter in healthy subjects, and ocular hypertensives . In contrast, arteriolar narrowing has been demonstrated in healthy eyes when topical beta‐blockers are used .…”

Ocular signs of systemic hypertension: A review

“…The precision of image analysis has shown that the diameter of arterioles decrease after exercise (Kergoat and Lovaski, 1995), vary with the cardiac cycle (Chen et al, 1994), are larger in hypertensives (Houben et al, 1995) and can be increased by a carbonic anhydrase inhibitor (Rassam et al, 1993). There is debate over whether the change in blood vessel width is correlated with ocular blood ¯ow (Wolf et al, 1998;Sugiyama et al, 2000), but it is correlated with BP (Houben et al, 1995;Hubbard et al, 1999).…”