Gene therapy is a process of treating a disease by using nucleotides, usually DNA or RNA, that affect the function of specific cells directly. In its most basic form, gene therapy could be a means of replacing a missing gene in a recessive disease. Recent work on the retina has shown it to be an ideal target for gene therapy using an adeno-associated viral (AAV) vector, which is a parvovirus that happens to infect retinal cells highly effectively. Gene therapy has recently been shown to be successful in treating some patients with a rare form of retinitis pigmentosa, a disease that affects up to 1 in every 3,000 people in the UK and leads to blindness. The procedure of injecting AAV under the retina is relatively straightforward and involves a standard eye operation, known as vitrectomy, followed by injection of vector in about one tenth of a millilitre of fluid through a very narrow needle. This operation can be performed under local anaesthetic and poses minimal risks to patients.

Our current research is now to develop gene therapy further for other retinal diseases. We have a facility for making adeno-associated viral vectors and laboratory facilities to test the therapeutic potential of these vectors in the eye. We are particularly interested in choroideraemia, Stargardt's disease and retinitis pigmentosa due to mutations in the gene encoding rhodopsin.

Gene therapy surgery

Here viral vector particles (in green) are shown being injected under the macular region of the retina.