Candle in the Dark ‘managed by the King Baudouin Foundation’

What therapies are currently available?

As mutations in genes cause LCA, gene therapy is a logical treatment option. Gene therapy has recently been used to effectively treat one variant of LCA. The treatment uses eye surgery to insert a good copy of the defective gene into the retina of LCA patients. Over the last few years, scientists and patients alike have seen very encouraging progress using this form of treatment. Indeed, young patients who have undergone this procedure are making significant progress with improved eyesight, and they can expect further degeneration to be halted. However, this treatment is currently only available for one subtype of LCA, and should be performed at a very young age. Hence, there is no treatment for the majority of LCA patients at this moment.

What future therapies are likely?

So far, gene therapy is the area of research and treatment to have yielded the most promising results.

Pharmacological treatment is also a therapeutic option under scientific investigation. This involves the use of drugs to slow down the degenerative process. In some cases drugs can even improve sight and would certainly mean many more years of functional vision for LCA patients. Experiments on animal models of these diseases have shown promising results.

Ocular cell transplantation is another area of research. As retinal photoreceptor cells are impaired in the majority of inherited retinal diseases, the idea is to replace them by cell grafts from a healthy donor eye. Research is in its very early stages, with only partial success in animal models, but there certainly is a potential to develop this approach into a proper treatment.

Stem cell therapy is also promising in this area. Stem cells are found in embryonic tissue, and have the theoretical potential to develop into any kind of body cell. The basic idea in the case of LCA is that stem cells could be used to help replace existing dead photoreceptor cells or even restore the entire retina in case of advanced degeneration, thus restoring sight. However the mechanism by which the stem cells can be transformed into a fully functional retinal cell such as photoreceptor cells, still needs to be fully understood. Hence, there is still a long way to go before this approach can be developed into a clinically applicable treatment option.

Before

These two clips show the remarkable progress of a young boy, Corey Haas, after undergoing gene therapy for his form of LCA at the Children’s Hospital of Philadelphia, Philadelphia, PA, USA. Corey suffers from LCA due to a mutation in both of his copies of the RPE65 gene. Researchers have had promising success in treating this type of LCA. The first clip shows Corey going through an obstacle course with his untreated eye (his treated eye is patched), the second clip shows Corey doing the same obstacle course with his treated eye. At this initial stage, only one eye at a time was treated. Success with this type of treatment for LCA due to mutations in the RPE65 gene has provided proof of concept. Consequently, it is expected that this approach will be applied to many more types of LCA, as well as other inherited retinal diseases, in the coming years.