Is Viagra Lost Link For Blindness?
Viagra has also been in the news because of its possible link with sudden failure of the blood supply to the optic nerve. That effect eyes & causes blindness called NAION, or non-arteritic anterior ischemic optic neuropathy.
(PRWEB) July 15, 2005
Federal health officials are examining rare reports of blindness among some men using the impotence drug Viagra. FDA clinical trials show that taking Viagra, especially at high doses, can cause some retinal dysfunction and affect sight for a number of hours. Studies show visual disturbances described as a bluish color tinge to the visual field and light sensitivity.
The Food and Drug Administration still is investigating, but has no evidence to determined the long-term effects of Viagra yet that the drug is to blame, said spokeswoman Susan Cruzan.
Viagra has also been in the news because of its possible link with sudden failure of the blood supply to the optic nerve. That effect eyes & causes blindness called NAION, or non-arteritic anterior ischemic optic neuropathy. It can occur in men who are diabetic or have heart disease, the same conditions that can cause impotence and thus lead to Viagra use. The FDA has 50 reports of the blindness. Viagra has been taken by more than 23 million men worldwide.
What is NAION?
NAION is one of the most common causes of sudden vision loss in older Americans. The condition leads to swelling around the optic disc, a connection point where the optic nerves reach the back of the eye. Ultimately, this swelling compresses the optic nerves and causes a rapid drop in vision. About 6,000 people develop NAION each year, according to the National Eye Institute.
How does NAION develop?
The symptoms are painless and often appear without notice. In a study led by researchers at the University of Iowa, about three quarters of NAION patients first discovered their vision was blurry and impaired after waking up in the morning. The condition starts in one eye and can cause complete blindness if both eyes are eventually affected.
Is there a strong reason to suspect that Viagra raises the risk of blindness?
The seven men in Pomeranz's recent study all developed NAION soon after they took Viagra. After taking two blue Viagra pills the day before, one 50-year old man said he felt "a flashbulb go off in my eyes." The onset of vision loss within hours of taking Viagra "supports an association between use of this agent and NAION," Pomeranz wrote. However, NAION appears suddenly in some 6,000 people a year for a variety of unknown reasons. "We don't really know what the natural history of NAION is," said Dickersin. Pomeranz is also cautious about Viagra causing NAION: "A definite casual relationship cannot be established at this time," he noted.
Is the vision loss substantial?
NAION can be disabling, especially if it affects both eyes. In the National Eye Institute study, whatever gains the patients had were partly lost after two years. But even with declining eyesight, most had better vision than when they were first afflicted with NAION. "These improvements are a noticeable difference," Dickersin said.
Is there any treatment for NAION?
There is no effective treatment as of yet, although researchers are examining different therapies in clinical trials.
Who is at risk for NAION?
Those who have bad eyesight already appear to have the highest chance for developing NAION. While people who have diabetes, hypertension or high cholesterol seem to be a greater risk for NAION as well, there is some debate on how much. "None of these systematic disorders are firmly associated with NAION, and diabetes could only account for only a minority of the cases," stated Simmons Lessell, MD, of the Massachusetts Eye and Ear Infirmary in an editorial for the Archives of Ophthalmology.
CASE STUDY
In the study, seven patients between the ages of 50 and 69 had typical features of NAION within 36 hours of taking Viagra. Seven similar cases have been previously reported. All of the patients, though, had at least one arteriosclerotic risk factor, including hypertension, diabetes, hypercholesterolemia, or hyperlipidemia, and they also had a low cup-to-disk ratio, which is a way doctors measure the small circular indentation where the optic nerve connects to the eyeball. Pomeranz says the low cup-to-disk ratio means that the blood vessels and nerves are tightly bundled together into the small space in the back of the eye. And it is this constriction of blood vessels, he says, which promotes NAION.
What are the general precautions for taking Viagra?
--Men who are taking medications that contain nitrates, such as nitroglycerin, shouldNOT use Viagra. The two medications taken togethermay decrease blood pressure to the extent that adverse effects may occur.
--Viagra should NOT be used by women or children.
--Viagra's use in combination with other ED treatments has not been studied, therefore, its use in combination with other treatments is NOT recommended.
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