The first clinical trial in Europe using human embryonic stem cells will take place at the Moorfields Eye hospital in London as reported by the Massachusetts-based stem cell research company, Advanced Cell Technology.

Doctors will be injecting retinal cells into the eyes of 12 patients with Stargardt's macular dystrophy, an incurable disease, which causes progressive sight loss.

Stargardt's disease is an inherited disorder that causes progressive vision loss through the thinning of retinal pigment epithelial cells at the centre of the retina, the region where the eye forms its sharpest images.

The safety of using replacement retinal cells known as retinal pigment epithelial cells, derived from human embryonic stem cells, will be tested in this trial.

The loss of replacement retinal cells usually begins between the ages of 10 and 20 years and leads to light-sensitive rods and cones in the eye dying off. This ultimately causes vision loss and even blindness.

In the event of the treatment working, the replacement retinal pigment epithelial cells will grow and eventually restore the retina to a healthy state that can support light-sensitive cells required for sight.

In November 2010, Advanced Cell Technology became the first to launch a U.S. trial of embryonic stem cells to treat Stargardt's disease. This was followed in January by a second trial of the method in patients with dry age-related macular degeneration.

Former president, George W. Bush, had blocked government funding for human embryonic stem cell research on new cell lines citing religious grounds, a ban which President Barack Obama lifted in 2009.

The technology has raised objections by conservative and religious opponents who say it should be banned because the cells' extraction involves the destruction of a human embryo.

The use of human embryonic stem cells, which can become any cell in the body, has been considered by researchers as capable of great regenerative potential against many disorders such as spinal cord injuries, Parkinson's, blindness and diabetes.