A group of patients with common but incurable eye diseases that can lead to blindness are to have cells injected into their eyes in two groundbreaking trials of a therapy that could heal the damage wrought by the conditions.

Doctors have drawn up plans to treat the first of 24 patients, who have been recruited to the trials, starting in July, at the Jules Stein Eye Institute, at the University of California, Los Angeles.

The medical teams hope to slow, halt or even reverse the effects of the diseases by injecting healthy retinal cells into the eye. . The treatment is controversial because the replacement retinal cells – known as RPE, or retinal pigment epithelial cells –are derived from human embryonic stem cells.

The announcement of the trials is a landmark for the Massachusetts-based company Advanced Cell Technology, which has been developing the therapy for 10 years.

In one trial the treatment will be given to a dozen patients with an eye disorder called dry age-related macular degeneration (dry AMD). The second trial will focus on the same number of patients with the condition known as Stargardt's macular dystrophy, which typically strikes younger people, aged 10 to 20.