Viagra May Cause Vision Loss In a new study, US researchers describe seven patients who developed nonarteritic ischemic optic neuropathy (NAION), an eye problem that can result in permanent vision loss...

Viagra FAQ You must be sexually stimulated for VIAGRA to work. In one study, VIAGRA was shown to work in some men in as quickly as 14 minutes...

Can Viagra Cause Blindness?

AARON BROWN, CNN ANCHOR: Good evening again. If you've ever seen a prescription drug commercial, in other words, if your television works at all, you've gotten to know the fast talking guy, the one that tells you about the dizziness, fainting spells and dry mouth. Today the Food and Drug Administration said it wants to give him one more thing to mention maybe. It is asking the maker of Viagra to update its warning label to mention vision loss.

So far the numbers are tiny and the connection not fully explored, but given how many people who use Viagra and drugs like it to treat impotence of just for the thrill, nobody's taking any chances. So, we begin tonight with Dr. Sanjay Gupta.

DR. SANJAY GUPTA, CNN SENIOR MEDICAL CORRESPONDENT (voice-over): The concern isn't new. It has been known for years that users of Viagra could experience short term vision changes, seeing green or bluish hues.

MICHAEL BERELOWITZ, VP WORLDWIDE MEDICAL, PFIZER: The first reports we were aware of was in 2000. More cases were published in the literature in March of this year.

GUPTA: The numbers are small, extraordinarily small, only 38 Viagra users of the more than 20 million who take it have come forward with vision problems. There have also been four users of Cialis and one with Levitra with similar problems, the pills manufacturers say.

They say the vision loss is caused by a sort of stroke affecting the blood vessels of the eye. That stroke in the back of the eye occurs when the blood vessels become choked off, eventually causing some of the cells in the eye to die.

Interestingly, the number of people who get the same type of stroke is actually about four times higher for people who don't take Viagra, the study's researchers say. But it's the relationship of timing between someone taking the drug and then within a short time getting visual problems that raised the red flags.

DR. HOWARD POMERANZ, UNIVERSITY OF MINNESOTA: Well, this patient that I just described from 1998 noticed the effect within 45 minutes after using the drug. Most of these patients experience this within hours.

GUPTA: And what Dr. Pomeranz who published the research showing the association noticed was not complete blindness, but things like loss of peripheral vision or a worsening of vision, for example, going from 20/20 to 20/40.

The truth is, It may be difficult to ever show a link between these medications and vision problems. That's because the same problems who get the stroke in the back of the eye are those with high cholesterol, high blood pressure, diabetes and a history of smoking. They're also more likely to have erectile dysfunction and take a medication like Viagra.

BERELOWITZ: You have the same group of patients with the same characteristics who might be at risk for this very, very infrequent condition that affect the eyes.

GUPTA: Still, if you happen to be one who actually reads those package inserts, you won't find reference to visual loss in there. But Pfizer is talking to the FDA about whether to add it.

Still worried?

POMERANZ: Well, I think there's some concern, but I don't think that everyone needs to go running in panic to their doctors.

GUPTA: And certainly, if you ever had a visual problem after taking Viagra, Levitra or Cialis talk to your doctor about getting your eyes checked.

Dr. Sanjay Gupta, CNN, reporting.

BROWN: Flesh out a bit more on the science and the medicine behind the concerns here with Viagra and the other drugs, we spoke earlier tonight with Dr. Pomeranz again.

BROWN: Do you know what it is about the drug that causes this problem when the problem is caused?

POMERANZ: Well, I only have a hypothesis. I don't have a certain answer. But I think it has something to do with what the drug may cause in terms of circulatory changes to the optic nerve.

BROWN: Did anyone go completely blind forever?

POMERANZ: Well, it depends what you mean by blind.

BROWN: Can't see.

POMERANZ: Yes.

BROWN: Forever.

POMERANZ: Yes. The patients in these studies that I reported all have permanent vision loss. This isn't a temporary transient color change that patients get for a few minutes or an hour that goes away. This is permanent damage that occurs to the eye.

BROWN: So you're talking about someone who could see yesterday and can't see anything, essentially anything.

POMERANZ: Correct. It could be a loss of eye chart vision, instead of being 20/20, they might be 20/50, 20/200. Or they may have peripheral visions. They might still have 20/20, but have lost half of all their peripheral vision.

BROWN: OK. I think when I say blind, I mean I'm not trying to be cute here, I mean like Ray Charles, blind. You can't see anything.

POMERANZ: No, I don't think that applies to people here in the study. Maybe one of the patients out of this most recent study that came out had really poor vision, meaning they could barely see light or maybe a hand moving in front of them. But that was maybe one patient out of the seven. The rest of them had vision that was much better than that.

BROWN: One of the things that the piece that precedes this conversation says, and that Pfizer says, is that the people that there's a certain predisposition that they have hypertension, or they are smokers or they're overweight. But what I hear you saying is that actually it's not quite that simple. That you might be perfectly healthy in all respects, nonsmoking but you have this thing in your eye that makes it vulnerable.

POMERANZ: Correct.

BROWN: Is that can you check that?

POMERANZ: Yes, by looking through the pupil into the back of the eye, you can look at the optic nerve and see if the optic nerve has this structure.

BROWN: Is the incidents of this enough so that doctors prescribing it ought to send a patient to you or someone like you first to look in the back of their eye and see what's going on?

POMERANZ: Well, it is kind of difficult to answer that question. The number of people who probably have this particular structure of the optic nerve is very small to begin with, if you just took a cross section of the population. So you'd be screening a lot of people to find people who have this particular nerve configuration.

I've actually thought about this issue myself and debated is it worth saying screen everybody. But I think you'd be looking at hundreds of thousands of people to find a few people who would fit that category. So, I'm not sure that's the most efficient way to do it.

BROWN: How long does the test take?

POMERANZ: You can pick up an ophthalmoscope and look at the back of the eye, less than a minute.
BROWN: So, in that sense. I presume that before you before someone prescribes Viagra, they check their blood pressure and probably check other things.

POMERANZ: Assuming they get it from a legitimate means.

BROWN: It takes at least as long as a minute to look in their eye.

POMERANZ: Sure. So yes, an internist or family physician could pick up their ophthalmoscope and look at the back of eye and see if they have this small cupdisperatio (ph).

BROWN: Last question. Are you surprised at the flurry of attention that the study has received today?

POMERANZ: Well, it kind of started as a trickle. And it suddenly turned into an avalanche that's kind of overwhelmed me all day long. It has kind of been an interesting experience, to say the least.

BROWN: I'll bet it has. Nice to meet you.

POMERANZ: Thank you very much.

BROWN: Have a great holiday weekend.

POMERANZ: Thank you. You too.