Two medications used to treat erectile dysfunction in men (tadalafil and sildenafil) do not appear to have visual side effects when taken daily for six months, despite concerns about eye-related complications, according to a report in the April issue of Archives of Ophthalmology.
The advent of the medications sildenafil citrate (sold as Viagra), tadalafil (sold as Cialis) and verdenafil hydrochloride (sold as Levitra) has profoundly changed the treatment of erectile dysfunction, according to background information in the article. These medications are known as selective phodiesterase type 5 (PDE5) inhibitors because they treat erectile dysfunction by interfering with the action of the compound PDE5 on the blood vessels in the penis. However, PDE5 inhibitors may also act on similar compounds in the retina, the part of the eye that receives and transmits images. Mild and transient blurred vision, blue-tinged vision and altered light perception have been reported by men taking these drugs, and some visual complications of long-term use have been suggested.
William H. Cordell, M.D., of Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, and colleagues conducted a randomized placebo-controlled study to assess changes in the retina among men taking tadalafil or sildenafil. A total of 244 healthy men, some with mild erectile dysfunction, age 30 to 65 were recruited. Of these, 85 were randomly assigned to take 5 milligrams of tadalafil, 77 to take 50 milligrams of sildenafil and 82 to take a placebo daily for six months. The men underwent comprehensive ophthalmologic examinations including electroretinography (a test to measure the electrical response of the light-sensitive rods and cones in the eye, used to detect diseases of the retina) before, during and after treatment.