Asahikawa, Japan - Results from a small pilot study suggest that statins might be used to treat retinal ischemic disease [1]. Investigators report that treatment with simvastatin increased blood-flow velocity in the retinal arteries and veins and decreased intraocular pressure.

"In the present study, we observed for the first time (to our knowledge) that systemic administration of simvastatin induced an increase in the blood flow in retinal arteries and veins and the plasma nitrite/nitrate levels in healthy men," writes lead investigator Dr Taiji Nagaoka (Asahikawa Medical College, Japan). "These results suggest that simvastatin increases retinal blood flow, probably via the increase in nitric oxide."

Writing in the May 2006 issue of the Archives of Ophthalmology, Nagaoka and colleagues point out that previous studies have shown that long-term statin therapy may contribute to reductions in the risk of age-related macular degeneration, diabetic retinopathy, and glaucoma, all ocular disorders thought to be associated with impaired ocular circulation. In addition, with the known pleiotropic effects of statins, such as the ability improve endothelium-dependent relaxation, investigators sought to investigate whether systemic statin therapy could improve retinal circulation.

In this small crossover study, the Japanese investigators randomly assigned 12 healthy men to receive simvastatin 20 mg or placebo for seven days. To estimate the blood flow in the retinal arteries and veins, investigators used laser Doppler velocimetry. Intraocular pressure and plasma nitrite/nitrate levels, stable end products of nitric-oxide metabolism, were also measured.

Ninety minutes after the administration of simvastatin, there were no changes in the diameter, velocity, or blood flow in the retinal arteries and veins compared with baseline. Intraocular pressure did decrease significantly after 90 minutes, from 14.3 mm Hg at baseline to 12.6 mm Hg. After seven days, changes in the diameter of the retinal artery and veins were not significant, but blood velocity and blood flow did increase significantly. Blood velocity increased 20% and blood flow 21% in the retinal arteries and 21.6% and 23% in the retinal veins, respectively. These changes were significantly greater with simvastatin than with placebo (p<0.05).

In looking at the possible mechanisms of benefit, Nagaoka and colleagues note that plasma nitrite/nitrate levels were significantly increased from baseline in patients treated with simvastatin, suggesting improved nitric-oxide release. They point out, however, that this increase in nitrite/nitrate levels might not be the result of nitric-oxide release in the retina, and further study is needed. Moreover, studies in women and in those with diabetes, hypertension, or hyperlipidemia will also be needed to see whether the improvements in retinal circulation can be replicated in these patients.