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Viagra Could Harm Vision

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The active ingredient in the erectile dysfunction drug Viagra can cause unusual visual responses in people who carry a common mutation for eye disease and have long-term detrimental effects on their vision.

Sildenafil can inhibit an enzyme that is important for transmitting light signals from the retina to the brain. Clinical trials of Viagra have found that high doses can cause transient disturbances in the vision of some healthy people.

“Side-effects can include sensitivity to bright light, blurred vision and altered colour vision,” says Dr Lisa Nivison-Smith of The University of NSW. “We are concerned that people who have normal vision but who carry a single copy of the mutant gene for the blinding disease retinitis pigmentosa could be more susceptible to these changes.”

A team led by Dr Nivison-Smith and Prof Michael Kalloniatis of UNSW studied the effects of a single dose of sildenafil on normal mice and mice with a single copy of the mutant gene. They reported in Experimental Eye Research that the normal mice had a transient loss of visual function after sildenafil treatment, but this effect was heightened and lasted longer in mice with the mutation. They also found early signs of cell death in the eyes of carrier mice, but not in the normal mice, suggesting that sildenafil may cause degeneration in carriers of retinal disease.

“These...

The full text of this article can be purchased from Informit.