A new research has revealed that erectile dysfunction drugs can affect vision of genetically susceptible users.
Research at University of New South Wales found that sildenafil, an active ingredient in the erectile dysfunction drug Viagra, can inhibit an enzyme which is important for transmitting light signals from the retina to the brain and its use in high doses can cause transient disturbances in the vision of some healthy people.
Researcher Lisa Nivison-Smith said that side effects can include sensitivity to bright light, blurred vision and altered colour vision and 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.
The study showed that the normal mice had a transient loss of visual function after sildenafil treatment, but this effect was heightened in the mice with the mutation, and the response lasted longer.
The researchers also found early signs of cell death in the eyes of carrier mice, but not in the normal mice, suggesting sildenafil may cause degeneration in carriers of retinal disease.
Nivison-Smith added that a better understanding of the effect of this family of erectile dysfunction drugs could help scientists and clinicians plan more successful strategies to account for factors such as a patient's medication and genetic makeup in diseases which cause blindness.
The results are published in the journal Experimental Eye Research.