Purpose: To assess the state of knowledge of photoreceptor dystrophies.
Methods: The current literature concerning photoreceptor dystrophies is reviewed, and their potential impact on concepts of pathogenesis of disease and clinical practice is assessed.
Results: As a result of cooperative investigative work between researchers in various disciplines, major advances in the classification of retinal photoreceptor dystrophies have been made. Until recently, classification of retinal dystrophies was based on clinical observation alone, and it was evident that this method was imprecise and of limited value. Largely through the work of molecular biologists, it has been shown that diseases clinically indistinguishable from one another may be a result of mutations on a variety of genes; conversely, different mutations on a single gene may give rise to a variety of phenotypes. It is reassuring that it is possible to generate concepts as to potential pathogenetic mechanisms that exist in retinal dystrophies in light of this new knowledge. More important for the clinician is the potential impact on clinical practice. There is as yet no therapy by which the course of most of these disorders can be modified. However, there is a considerable body of work in which therapeutic intervention is being explored, and many researchers now see treatment as a justifiable objective of their work.
Conclusions: Knowledge of the causative mutation is of value to the clinician in that it provides a precise diagnosis and allows the distribution of the abnormal gene to be documented fully within a family. To take full advantage of the opportunities provided by current research, clinical practice will have to be modified, particularly if therapy can be justified.