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Medical Forum / General / Vision / October 2005Viagra & Blindness: True or false?
Hi, My father is taking viagra and I'm concerned about it having attributed to causing blindness (NAION - Non-Arteritic Anterior Ischemic Optic Neuropathy). I've been researching for weeks in the internet but can't come up with something definite. The most logical is that viagra can lower blood pressure by 8 mg diastolic. How much would the blood pressure would have to be low such that it can't supply enough blood to the optic nerve causing NAION?? 60mg, 50mg, 40mg? What do you think? I told my father to jump up and run around after intercourse so that the blood pressure would increase and NAION would not occur. He has normal heart and don't have cardiac diseases. How many of you are taking viagra, levitra or cialis? How many of you are semi-blind have NAION? Personally. What do you think is the plausible mechanism. Viagra can cause dilations of the blood vessels. In NAION, constriction is supposed to occur causing stroke of the optic nerve. Thomas > My father is taking viagra and I'm concerned about it having > attributed to causing blindness (NAION - Non-Arteritic Anterior > Ischemic Optic Neuropathy). > > I've been researching for weeks in the internet but can't > come up with something definite. The most logical is that I'm not sure it deserves the alarm it got. It didn't hurt sales that much, and every drug has side effects. The incidence of NAION is pretty similar among 50/60-year-old males who _don't_ take Viagra. The concern is that in several cases, NAION seemed to follow soon after taking the drug. I use it on my doctor's advice, but minimum doses and not very often. He only gave me 12 last year. :) -MT, OD > > My father is taking viagra and I'm concerned about it having > > attributed to causing blindness (NAION - Non-Arteritic Anterior [quoted text clipped - 14 lines] > > -MT, OD The major risk factor is said to be smaller cup to disc ratio of about 0.1 to 0.2. I've been researching of the most plausible mechanism. Do you know how much systolic and diastolic (in mm HG) must the blood pressure drop before it cuts off blood supply to the optic nerve? Thomas > The major risk factor is said to be smaller cup to disc > ratio of about 0.1 to 0.2. I didn't know that. > I've been researching of the most plausible mechanism. > Do you know how much systolic and diastolic (in mm HG) > must the blood pressure drop before it cuts off blood > supply to the optic nerve? No I don't. I wonder if there's an association between NAION and nitrates or other agents that drop peripheral resistance. -MT > The incidence of NAION is pretty similar among 50/60-year-old males who > _don't_ take Viagra. The concern is that in several cases, NAION seemed to [quoted text clipped - 4 lines] > > -MT, OD That often?  SignatureJan (normally Dutch spoken) The ED drugs act as vasodilators. They reduce blood pressure by causing peripheral arterioles to dilate. Thats also the way that they stimulate penile erections. A plausable theory about the mechanism of action of the ocular side effect is that ophthalmic artery dilation allows excessive blood flow to the retina. If the blood flow into the eye exceeds the capacity of the ophthalmic vein to carry it out, then there is an accumulation problem similar in effect to a venous occlusion. Ocular signs include diffuse hemorrhage and edema. If the optic nerve within which the ophthalmic artery and vein are both located is already packed pretty tight (as evidenced possibly by low C/D ratio) then the possibility of this occurring might be greater. I'm not sure how much of this is just conjecture, and how much has been proven, but it certainly seems logical. RM PS-- I am not sure how significant this side effect really is. I have read somewhere that the incidence of this drug induced side effect occuring is not much different that the incidence of this occuring in persons not taking the drug anyway. I think the press, and the public in general, overreacts to scattered reports of drug side effects. ========= > Hi, > [quoted text clipped - 24 lines] > > Thomas > The ED drugs act as vasodilators. They reduce blood pressure by causing > peripheral arterioles to dilate. Thats also the way that they stimulate [quoted text clipped - 21 lines] > the drug anyway. I think the press, and the public in general, overreacts > to scattered reports of drug side effects. Can your scenerio cause SUDDEN vision loss 1 hour after taking viagra for example? Where did you hear that? Here's the 2002 Pomeranz report: http://www.centralfloridaurology.com/articles/PomeranzetalSildenafil.pdf I lost the link to the 2005 latest article but will look for it and post the link later. T > ========= > [quoted text clipped - 26 lines] > > > > Thomas This was explained to a group of optometrist during a continuing education class by a retinal specialist. I do not know theoretical vs. proven that it is. I central/major branch vein occlusion can happen fairly quickly-- within a few hours I think. I don't know about 1 hour. ------------ >> The ED drugs act as vasodilators. They reduce blood pressure by causing >> peripheral arterioles to dilate. Thats also the way that they stimulate [quoted text clipped - 69 lines] >> > >> > Thomas > Hi, > > My father is taking viagra and I'm concerned about it having > attributed to causing blindness (NAION - Non-Arteritic Anterior > Ischemic Optic Neuropathy). There is an association but cause is not established. The underlying vascular problems that may cause erectile dysfunction are the same vascular problems that cause NAION, so the Viagra use may have no causative effect whatsoever. Sort of like finding a link between cough syrup use and lung cancer; the answer is that smoking causes both the cough and the cancer. > I've been researching for weeks in the internet but can't > come up with something definite. The most logical is that > viagra can lower blood pressure by 8 mg diastolic. How > much would the blood pressure would have to be low such > that it can't supply enough blood to the optic nerve causing > NAION?? 60mg, 50mg, 40mg? What do you think? More likely that blood pressure drop is a red herring. Occulsion of the small blood vessels that supply both the optic nerve and the penis results in reduced blood supply to both organs and may cause NAION and erectile problems. > I told my father to jump up and run around after intercourse > so that the blood pressure would increase and NAION would > not occur. Or, given that he likely has small vessel problems, the vigorous activity of intercourse coupled with running around will cause a heart attack or stroke. Dr Judy > He has normal heart and don't have cardiac diseases. > [quoted text clipped - 7 lines] > > Thomas
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