Refractive Surgery Blog

I receive questions regularly from patients and colleagues about the safety of Viagra, Levitra and Cialis usage. Specifically, many patients have heard about the possible effects on one's vision and want to know if there is any truth to the "rumor." The answer, in a word, is yes. I will try to outline some of the well documented information about these drugs.

Since receiving approval by the FDA in 1998, Viagra (Pfizer Labs) has been prescribed well over 23 million times in the United States alone. The way this drug works is by inhibiting an enzyme (phosphodiesterase 5 or PDE-5) and enhances the effects of nitric oxide in the body. Nitric oxide stimulates the smooth muscle which facilitates blood flow and causes the desired effects. However, this class of medications can also affect arteries elsewhere in the body and the results are unwanted side effects. In addition, Viagra-like drugs also inhibit the effect of PDE-6, a closely related enzyme to PDE-5. This enzyme is present in retinal photoreceptors and when blocked, causes light sensitivity (photophobia) and/or blue tinged vision.

Systemic side effects of this class of drugs include:

• Headache
• Facial flushing
• Nasal congestion
• Nausea
• Other gastrointestinal problems
• Pulmonary hypertension

These side effects are dose related and occur in 3% of men taking 25 -50 mg to 50% of men taking 200 mg and 100% of men taking 600 -800 mg.

A rarer and poorly understood eye disorder called nonarteritic anterior ischemic optic neuropathy (NAION) has been reported in several men and is presently being investigated. NAION is the most common acute optic nerve disease in adults over age 50 and shares a number of common risk factors with erectile dysfunction (ED): age over 50, high blood pressure, high cholesterol, and diabetes. "Most of the cases in which NAION has occurred in men taking Viagra have involved patients with underlying anatomic or vascular risk factors associated with the development of NAION" according to Pfizer. In other words, it is not clear that there is a cause and effect relationship between Viagra use and NAION.

The bottom line is that one should not take these medications unless they are needed as there are serious health and visual risks associated with them. Patients with the following conditions should check with their ophthalmologist prior to taking any ED drug:

• Retinitis pigmentosa
• Diabetes
• Retinal pathology - including macular degeneration and optic nerve disorders

Also, check with your primary care physician to rule out other serious medical conditions that could be problematic with the use of this class of drug.

Read more about General Eye Care.

Stuart Lewis

Labels: Medications