Tapetoretinal degenerations: experiences, experiments and expectations

Tapetoretinal degenerations are a common cause for vision problems, but have until recently not been amenable to rational treatment. With rapidly increasing insights into basic neurobiology and pathobiology this has now begun to change. From having been a relatively small group of largely unknown yet fairly prevalent disorders, they are rapidly forming a large set of well defined diseases, and it is easy to predict that our knowledge about them will continue to increase for many years to come. Vitamin A (15,000 IU daily) is currently the only rational treatment available. However, in experimental animals, therapy strategies are now actively being developed along several different lines. Apoptotic photoreceptor cell death can be delayed with different drugs, and at least one of them, diltiazem, is approved for human use in cardiovascular diseases. It remains to be seen if it has any clinically significant effect in human tapetoretinal degenerations. Other strategies aim at counteracting the production of harmful protein variants, acting either on DNA or mRNA levels. Transgenes can also be used to induce the production of important but missing metabolic components. Finally, cells or retina sheets can be transplanted, either to replace failing cells or as a source for missing trophic factors. Neither of these strategies has yet been transferred to humans, but trials are under way. With the high increase in the flow of new information on tapetoretinal disorders, much more precise diagnoses and much improved treatments are soon to be expected, augmenting considerably the possibilities for ophthalmologists to help patients with such diseases. It is not likely that there will be a single treatment for all the many varieties. Instead, we are most likely going to see pharmacological treatments for some of them, DNA transfers for some, and transplantations for others.