A gene therapy that could restore the fading sight of the elderly is being tested on humans for the first time after positive results in blind mice.

It could be used to treat age-related macular degeneration, a common condition that usually first affects people in their 50s and 60s, scientists said.

It involves a one-time injection of a modified virus into the eye. This viral vector is altered to contain a synthetic gene that produces a protein that plays a critical role in the perception of light.