Even if taken daily over a six month period, the erectile dysfunction drugs tadalafil and sildenafil did not appear to trigger any eye-related complications, according to a report in the Archives of Ophthalmology. Sildenafil citrate (marketed as Viagra), tadalafil (Cialis) and verdenafil hydrochloride (Levitra) 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, it has been suspected that 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.
Now, William H. Cordell, from Lilly Research Laboratories, and colleagues have conducted a study to assess changes in the retina among men taking tadalafil or sildenafil. Among the men who completed the study, no significant differences were found between treatment and placebo groups on electroretinography, visual function tests, measurements of intraocular pressure (pressure within the eyeball) or assessments of the anatomy of the eye.
"There are several reasons ophthalmologists need to be acquainted with the pharmacologic profiles of PDE5 inhibitors and their potential side effects," the study notes. "The frequency of erectile dysfunction, which is a form of peripheral vascular disease that impairs men's abilities to achieve and maintain an erection, increases dramatically with age and in the presence of cardiovascular risk factors. Therefore, many men who take PDE5 inhibitors to treat their erectile dysfunction will also be followed up by ophthalmologists for ocular disorders such as diabetic retinopathy, macular degeneration and ocular vascular disease."
"Furthermore, PDE5 inhibitors can exert direct effects on the retina, and such effects probably account for many of the visual side effects such as blue-tinged vision and light sensitivity that have been reported," the researchers conclude. However, "our results indicate that there is no cumulative damage or effect of clinical significance for either 5 milligrams of tadalafil or 50 milligrams of sildenafil taken daily for six months."
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Source: Archives of Ophthalmology
