Viagra Links to Blindness

[Japanese]

Impotency drugs Viagra and Cialis may increase the risk of sudden blindness in men with a history of heart attacks or high blood pressure, research suggests.


A new study published in the British Journal of Ophthalmology is the latest to suggest a link between impotency drugs and a condition which could cause sudden blindness in one eye; non-arteritic ischaemic optic neuropathy (Naion). The authors recommended doctors discuss the risk with their patients.

However, the drugs' manufacturers have criticised the study as too small and said erectile dysfunction and Naion had many of the same risk factors, making it difficult to know if the drug or the underlying condition was to blame.

Last year, the United States Food and Drug Administration investigated reports of 38 cases of blindness among users of Viagra and four among Cialis users. In July it updated the labelling for all three impotency drugs, Viagra, Cialis and Levitra, and warned users who suffered a sudden loss or decrease of vision to stop taking the medicines and call a doctor.

At the time the FDA said it was not possible to determine whether the oral medicines were the cause of the eyesight loss or whether it was due to other factors such as high blood pressure or diabetes.

In the latest study by Alabama University researchers, 76 eye patients from one US clinic were asked about their lifestyle, their history of heart attacks, diabetes and high blood pressure, and if they had used Viagra or Cialis.

The researchers found no overall increased risk of Naion in the group which had used the impotence drugs. But it did find "a strong and statistically significant" risk amongst Viagra and Cialis users who had suffered a heart attack and a small statistically "borderline" increase in risk for those with high blood pressure.

The team suggested the drugs could be reducing blood flow to the optic nerve resulting in damage.

Also writing in the journal, Howard Pomeranz, a consultant paid to review cases of Naion associated with impotence drugs, said most cases had occurred within 24 hours of taking the drug, frequently when the man woke the next morning.

"In most of the cases, sexual intercourse did not occur after erectile dysfunction drug use so physical exertion related to sexual intercourse cannot be blamed for the vision loss."

He suggested further research on a larger group.

Christchurch urologist Sharon English said the drugs could not be prescribed to men who were taking nitrate-based medicines for angina so many of those who had suffered a heart attack were excluded.

However, she said the latest results were of interest because they appeared to support previous studies. "So if you have a finding like this, it is something you start mentioning to patients."

She would advise patients who noticed eyesight problems to stop taking the drugs and see their GP.

Barbara Thompson, who spent 16 years as a nurse counsellor for sexual dysfunction in Christchurch, had "very very rarely" heard reports of patients suffering visual disturbances after taking Viagra.

"I probably struck one person who had felt a visual disturbance while taking Viagra but it was momentary and goes when the drug wears off."

Thompson, who was sceptical of the study's findings, said: "It's a bit like (the claim that) masturbation makes you go blind."

A Christchurch Viagra user, who did not want to be named, said he suffered headaches the morning after using the drug "but it is worth it". He did not suffer heart problems but would reconsider taking the drug if he did.

Cialis manufacturer Eli Lilly said the study was limited by its size and dependence on a patient's recall, its observational nature, potential interviewer bias and the fact those in the study were all eye patients.

"Nevertheless, we continue to work closely with global regulatory bodies to examine this important issue and encourage men to talk with their doctors about this and erectile dysfunction," said the company.

Viagra maker Pfizer said Naoin was a rare event, affecting between two and 10 in every 100,000 people over the age of 50. High blood pressure, high cholesterol and diabetes were risk factors for both Naoin and erectile dysfunction.