What is retinitis pigmentosa?
Retinitis pigmentosa is the most common hereditary disease of the retina that affects about 1 in every 4,000 people and is characterised by the gradual degeneration of the retinal photoreceptor cells: the cone and rod cells.
What causes this?
Due to the degeneration of the retinal photoreceptor cells, there is a gradual decrease in sight.
How can it be prevented?
There is no treatment at present and its seriousness makes it one of the ocular pathologies of genetic origin on which the most research is being conducted.
The first symptoms are night blindness or being unable to adapt to darkness and loss of peripheral vision, resulting in tunnel vision. In more advanced stages, glares and cataracts are also commonplace, which can appear as a consequence of the process.
The degree of severity and progression that the pathology can reach is variable and depends on the mutated gene in each person and his/her family, because retinitis pigmentosa is a hereditary disease and it is therefore essential to know the patient’s family background. Finding the mutated gene in each case, from among more than 50 that can cause this pathology, requires a correct prior clinical diagnosis so that, in this way, customised and a precise genetic diagnosis can be made to determine the kind of heredity and transmission of the disease and identify the pre-symptomatic and carrier relatives.
The genetic diagnosis is also the first step required to apply gene therapies, based on replacing the defective gene with another functional one. Generally, these therapies are conducted by means of a modified virus that contains the functional gene and acts as a vector to be inserted in the patient’s retinal cells. Although still in an experimental stage, gene therapies are showing very encouraging results and are opening a new possibility for patients suffering from retinitis pigmentosa, a disease that has no cure at the moment.
Another of the research lines in process is cell therapy, one of the main novelties presented at the II Trends in Surgical & Medical Retina. As explained by the North American doctor, Marco Zarbin, at the international congress held at IMO last June, recent phase I studies on humans have proven that the use of stem cells to replace damaged cells of the retina leads to improvement of patients’ visual acuity. Therefore, what is being achieved with this therapy is the replacement of the patient’s atrophic photoreceptor cells, which will not be regenerated, for embryonic or pluripotent stem cells extracted from the skin or other parts of the eye. The latter, after being modified, can perform the same function as the retinal cells before they were damaged.