Hereditary Retinal and Choroidal Dystrophies

Abstract

Inherited retinal and choroidal dystrophies are a clinically and genetically heterogeneous group of disorders and can occur isolated or in association with other systemic disorders. The clinical presentation of these dystrophies is variable. They can present at birth, during childhood or adulthood; the disease can be stationary or progressive; cause profound or mild visual loss; predominantly involve rods or cones or both; be a central receptor disease or primarily involve the choriocapillaries. The photoreceptors, retinal pigment epithelium and choriocapillaries are in close relationship and are interdependent on one another in their functioning and maintenance of structure. Any disorder, genetic or environmental, which causes degeneration of any of these layers will likely eventually result in involvement of the others, making accurate diagnosis difficult. The classical diagnostic approach for retinal/choroidal diseases has been clinical exam by ophthalmologists assisted by electrophysiological and psychophysical tests such as the electroretinogram, electrooculogram, dark adaptation, visual field test and ocular coherence tomography. With the recent advances in molecular genetics, the genetic etiology of a large number of retinal/choroidal diseases has been identified. Clinical genetic testing provides the option for more accurate diagnosis, genetic counseling, prognosis, therapeutic and research options to individuals and families with inherited diseases.