Researchers at the University of New South Wales in Australia have found Viagra may have long-lasting adverse affects on the vision of some users. Users who are at greater risk are individuals who carry the genetic mutation in the RD1 gene for retinitis pigmentosa (RP).
Viagra and other erectile dysfunction treatments contain the active component sildenafil. Sildenafil suppresses the enzyme PDE5, which sustains blood flow to erectile tissue. Sildenafil also impacts the enzyme that positively contributes in the visual cycle within the phototransduction pathway, called PDE6.
The new research studied mice treated with sildenafil. Mice with healthy retinas showed some disturbances, but generally improved within two days. Mice without functional RD1 genes did not recover for up to two weeks, indicating a direct effect of the drug on both the inner and outer retina. Early signs of retina cell death were also discovered by researchers, which suggests sildenafil may cause cellular degeneration in the longer term.
Authors from the study write, “The results of this study are significant considering approximately one in 50 people are likely to be carriers of recessive traits leading to retinal degeneration.”
The research is published in the journal Experimental Eye Research.
Source: https://www.optometry.co.uk/news-and-features/news/?article=6450