Drugs for erectile dysfunction have become very popular. They include avanafil (Stendra), tadalafil (Cialis), vardenafil (Levitra) and the original, sildenafil (Viagra). Such drugs are referred to as phosphodiesterase 5 inhibitors, abbreviated PDE5Is. Most men are interested in the benefits of such medications. The risks, on the other hand, get much less attention. A study published in JAMA Ophthalmology, April 7, 2022 reveals an often overlooked complication of PDE5Is: vision loss from Viagra and similar ED drugs.
New Research About ED Drugs and Vision:
Canadian researchers reviewed data from a US database that included 213,033 PDE5I users. Of that total, 123,347 were using generic Viagra (sildenafil), 78, 609 were taking generic Cialis (tadalafil), 6,604 were relying on generic vardenafil (Levitra) and 4,473 were avanafil (Stendra) users. Stendra is not yet available in generic form. Each of the men were matched to 4 controls.
The authors point out that ED drugs:
…”are one of the most prescribed classes of medications in the US.”
According to these researchers, here is why they undertook this investigation:
“In 2020, there were approximately 20 million monthly prescriptions for PDE5Is in the US.7 Given the popularity of these drugs and the paucity of data on the magnitude of the risk of SRD, RVO, and ION, we sought to undertake a large cohort study to quantify the risk for SRD, RVO, and ION associated with use of PDE5Is.”
What Are SRD, RVO and ION?
These scientists were looking for vision loss from Viagra and other ED drugs.
- SRD stands for Serous Retinal Detachment. This occurs when fluid builds up under the retina and causes detachment. It can occur after an injury to the eye or as a result of some serious health conditions.
- RVO is short for Retinal Vascular Occlusion. Occlusion means blockage. Vascular means blood vessel. If blood, oxygen and other nutrients are blocked from getting to the retina, this is not good for the eye! If the vein is blocked, it cannot carry waste and other byproducts away from the retina.
- ION is Ischemic Optic Neuropathy. This occurs if there is not enough blood flow to the optic nerve in the eye. If this happens, there can be a sudden loss of vision.
None of these are desirable, to put it mildly. Needless to say, readers of our newspaper column have been worried about such problems. Here is one such question:
Is There a Chance of Vision Loss from Viagra?
Q. I am concerned about the possibility that Viagra for erectile dysfunction might affect vision. I have read about this, but I have not been able to get my doctor or pharmacist to tell me how often vision loss occurs and whether it is temporary or permanent. I’d like to use the drug, but I don’t want to risk my sight. Do you have more information?
Vision Loss from Viagra Is Rare but Serious:
A. The FDA warns physicians to alert their patients to a rare but serious vision problem. Non-arteritic anterior ischemic optic neuropathy (NAION) has been linked to drugs like sildenafil (Viagra) and tadalafil (Cialis) (Neurology Clinics, Feb. 2017).
Pfizer (maker of Viagra) maintains that the condition is quite rare, occurring in 2.8 per 100,000 men using erectile dysfunction medication for a year (International Journal of Clinical Practice, April 2006). On the other hand, few studies last more than six months or collect long-term side effect information (Urology, Oct. 2009).
What Did the Study in JAMA Ophthalmology, (April 7, 2022) Reveal?
The authors report:
“Findings: This large cohort study of 213 033 men found an increase in the risk of SRD, RVO, and ION associated with the use of PDE5Is in those who regularly used these drugs.”
They go on to say:
“To our knowledge, this is the largest epidemiologic cohort study that has examined 3 important ocular outcomes associated with use of PDE5Is, one of the most prescribed classes of medications. We found a combined increase in the risk of SRD, RVO, and ION associated with the use of PDE5Is in older men. For each individual outcome, use of PDE5Is was independently associated with an increase in risk.”
Is Vision Loss from Viagra and Other ED Drugs Plausible?
As a pharmacologist, I like to know if there is a reason for a particular side effect.
An invited commentary in JAMA Ophthalmology, (April 7, 2022) offers just such plausible mechanism of action:
“Central to any implied causal relationship between the medication and an adverse event is a proposed pathophysiologic mechanism. Nocturnal hypotension has been put forth as a primary precipitating factor for ION, and PDE5Is lower systemic blood pressure and are often taken at night.”
What does that mean in English? ED drugs can lower blood pressure. Taking an ED medicine in the evening might lower blood pressure while a man is sleeping. Since blood pressure normally drops overnight, the additional hypotension might trigger inadequate blood flow to the optic nerve. According to these authors, people using PDE5Is have reported hundreds of cases of ischemic optic neuropathy (ION) to the FDA.
The eye researchers who wrote the commentary also offer plausible mechanisms for other kinds of vision loss from Viagra and related ED drugs.
What to Do About Vision Loss if Taking a PDE5I:
The authors of the latest study offer this recommendation:
“Meaning: Results of this study suggest that individuals who regularly use PDE5Is should be cognizant of ocular adverse events associated with these drugs and alert their physicians if they experience any visual deficits.”
In other words, if a man experiences any visual changes while taking an ED drug, he should report this side effect to an eye doctor immediately. These serious complications are relatively rare, but as this reader points out, they can have a substantial impact on quality of life.
Ed describes his problem with Cialis:
“Three years ago, after prostate surgery, my urologist prescribed a thrice-weekly low dose of Cialis as medical therapy. After two months, he doubled the dose, which I started immediately that evening. The next morning my 20/15 vision in my left eye had become blurred to 20/600. Although the vision has improved somewhat, that eye is functionally useless for reading, driving, watching films,etc. This is permanent.
“Contributing to the NAION incident was probably the fact that I had a disc at risk – my cup to disc ratio was 7% instead of the normal 30%. My ophthalmologist had never measured it despite annual check ups. There’s not a lot of research being done on this, but one thing that I read, and I am expecting, is that the same thing will happen to my other eye for one reason or another if I live long enough. Needless to say, I am taking all of the precautions to ward off an incident in my right eye, and completing my bucket list as fast as I can.”
Is It NAION?
Men who notice a sudden deterioration in their vision, especially if it is in just one eye, should check with the doctor immediately. This could be the first symptom of NAION. Trouble seeing things in the lower part of the field of vision should also prompt an eye check-up. The ophthalmologist will test the visual field and look in the eye to see if there is swelling in the optic nerve.
Among people taking sildenafil at high daily doses to treat pulmonary arterial hypertension, serious visual problems were uncommon (BMJ, Feb. 2, 2012). However, approximately 2 percent of those taking the medicine had retinal hemorrhages during the trial, while none of those taking placebo experienced such an adverse event. Any vision loss from Viagra should be reported immediately.
Drugs to treat erectile dysfunction may cause less serious vision problems more frequently. Increased retinal blood flow appears within one hour of taking any of these medicines (Journal of Ophthalmology, online Oct. 9, 2017). Adverse reactions may include temporary blurred vision, increased light sensitivity and a bluish tinge to vision (cyanopsia). These reactions are usually reversible.
We have one other unscientific suggestion. If the mechanism described above about “nocturnal hypotension” is real, it might make sense to use a drug such as Viagra earlier in the day. That way lower blood pressure during sleep might be less of a risk.
Please share your own experiences with drugs like tadalafil (Cialis), vardenafil (Levitra) and sildenafil (Viagra) in the comment section below.
