Implanted retinal cells derived from stem cells seem to be improving vision in some people in two early-stage clinical trials.

Steven Schwartz at the University of California, Los Angeles, Robert Lanza at Advanced Cell Technology in Marlborough, Massachusetts, and their team grew retinal pigmented epithelial cells from human embryonic stem cells and transplanted them into the retinas of 18 people who have one of two forms of macular degeneration, which results in the loss of central vision.

After about two years, there have been no serious side effects from the cells, such as abnormal growth. Ten participants reported seeing more letters on an eye chart than before the treatment.

The transplanted cells are support cells that do not directly enable vision, so it is not known how eyesight has improved. The authors could not rule out placebo and other bias effects.

Lancet http://doi.org/wdf (2014)