A viral infection has been linked with blindness in older adults when it affects the eye.
Human cytomegalovirus, a form of herpesvirus, is thought to cause neovascular age-related macular degeneration (AMD), which can lead to blindness.
Researchers from Georgia State University found that the virus causes the production of vascular endothelial growth factor, which is a signal protein that regulates the creation of new blood vessels.
When new blood vessels are created, retinal tissue destruction takes place and causes the development of wet AMD and blindness.
AMD is a common condition among older adults and there is currently no known cure for the condition.
Dr Richard D DIX, professor at the Georgia State Viral Immunology Centre's Ocular Virology and Immunology Laboratory, commented: "Prior to this work, cofactors for the development of AMD included genetics, a high fat diet and smoking. Now, we are adding an [infectious] agent as another cofactor."
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