Article

Erectile dysfunction agents, NAION: causal or coincidental?

It might be wise to counsel patients regarding the possible but likely low risk of NAION, especially for individuals with a higher risk for NAION.

Although several case reports have suggested a causal relationship between these drugs and NAION, the evidence is far from conclusive. The proponents of the causality argument suggest that in some cases there is a temporal relationship between taking the drug and the onset of visual loss; that there are potential "biologically plausible" mechanisms for these drugs to affect the blood supply of the optic nerve; that there may be analogy from the known visual side effects of the drug (e.g., transient blue vision); and that there have been a few anecdotal drug re-challenge examples.

FDA recommendations

Other studies

Fraunfelder et al. performed a retrospective observational case series of 892 reports from the National Registry of Drug-Induced Ocular Side Effects (Casey Eye Institute, Portland, OR), the FDA, and the World Health Organization (WHO).

They concluded that there was not sufficient evidence to discourage use of erectile dysfunction agents based upon ocular side effects. They conceded, however, that NAION is a "possible" association based upon the WHO classification but that "conclusive evidence linking ION to erectile dysfunction medications was lacking."

The Pfizer Web site reports that there have been more than 100 clinical studies of Viagra involving more than 13,000 patients with no cases of NAION. Reportedly, more than 170 million sildenafil prescriptions have been given (23 million men, 1 billion doses). Lee and Newman commented that even if NAION is causally related to sildenafil use, the rate of NAION must be extremely low, especially when compared with the published incidence rates for NAION in similar older-aged, vasculopathic populations of men who are not taking these drugs.

Newsletter

Don’t miss out—get Ophthalmology Times updates on the latest clinical advancements and expert interviews, straight to your inbox.

Related Videos
(Image credit: Ophthalmology Times) NeuroOp Guru: Using OCT to forecast outcomes in ethambutol optic neuropathy
(Image credit: Ophthalmology Times) Inside NYEE’s new refractive solutions center with Kira Manusis, MD
(Image credit: Ophthalmology Times) Dilsher Dhoot, MD, on the evolution of geographic atrophy therapy: where are we now?
(Image credit: Ophthalmology Times Europe) Anat Loewenstein, MD, shares insights on the real-world results of remote retinal imaging
(Image credit: Ophthalmology Times) Two-wavelength autofluorescence for macular xanthophyll carotenoids with Christine Curcio, PhD
(Image credit: Ophthalmology Times) FLIO and the brain: Making the invisible visible with Robert Sergott, MD
(Image credit: Ophthalmology Times) Structure-function correlates using high-res OCT images with Karl Csaky, MD, PhD
(Image credit: Ophthalmology Times) SriniVas Sadda, MD, on high-res OCT of atrophic and precursor lesions in AMD
(Image credit: Ophthalmology Times) Christine Curcio, PhD, shares histology update supporting review software and revised nomenclature for <3 μm OCT
(Image credit: Ophthalmology Times) ASCRS 2025: Eric D. Donnenfeld, MD, on the effect of lifitegrast clinical signs and biomarkers in dry eye disease
© 2025 MJH Life Sciences

All rights reserved.