RETINAL CELL SURVIVAL
A different sort of approach is a research effort to develop 'survival factors' which are means of either retarding or stopping premature cell death in the retina. A survival factor may, for example, be a synthetic protein in the form of a drug, which stimulates growth, and the survival cells in the retina. As a practical therapy, though, the drug still has to be delivered to the appropriate site in the retina. Because repeated injections into the back of the eye can be damaging, this may instead entail reliance on either a courier virus or implantation in some controlled-release form. The use of a survival factor as therapy would not correct the defect responsible for retinal degeneration but would work by slowing and, ideally stopping, premature photoreceptor death. While several drugs have recently demonstrated some effectiveness in animals under laboratory conditions, their safety and effectiveness as therapy have yet to be established through extensive clinical trials with human subjects.
Also seeking to promote survival of photoreceptor cells is research focusing on the role of oxygen in both the causation and treatment of retinal dystrophy. If it can be established that early depletion of photoreceptor cells creates toxic levels of oxygen in the retina which itself is destructive of photoreceptor cells, then regulation of the level of oxygen in the retina may come to be a means of therapy.