The progressive loss of photoreceptor cells in inherited retinal degeneration can cause blindness. However, despite the loss of photoreceptors in end-stage disease, other retinal cells remain structurally intact.

Expressing photosensitive proteins such as melanopsin, which is native to the human eye, in such cells through gene therapy could potentially rescue retinal function. The researchers report improved visual function following virus-mediated subretinal injection of the human melanopsin gene in a mouse model of retinal degeneration.

Assessments in the mice revealed that human melanopsin was present in the mice retinas for up to 15 months after the injection. Additionally, tests of pupil light reflex and behavioral light avoidance were administered 13 months after the injection.

In the pupil light reflex test, treated mice exhibited significantly greater pupil constriction than control mice; treated mice spent less time than control mice in a lighted chamber in the behavioral test. Moreover, treated mice exhibited an enhanced visual response upon recognizing objects in their environment.

According to the authors, the findings may have implications for the treatment of retinal degeneration in humans.

http://www.pnas.org/content/early/2017/09/26/1701589114