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RETINAL DEGENERATIVE DISEASESRetinal degenerative diseases are a complex group of conditions with different etiologies that result in a common outcome: photoreceptor apoptotic cell death ( 1-5 ). Accordingly, there are differences in how these conditions evolve. For instance, in retinitis pigmentosa (RP), rod photoreceptor death initially occurs in the periphery, whereas in age-related macular degeneration (AMD), death is initiated in the macular zone and spreads in later phases throughout the retina ( 2, 5 ). RP is a collection of inherited blinding diseases caused by the mutation of a wide variety of genes resulting in more than 150 abnormalities of photoreceptor-specifi c proteins, including mutations of rhodopsin, peripherin, the  -subunit of cGMP phosphodiesterase, and retinal outer-segment membrane protein 1 ( 6-8 ).Conversely, the etiology of AMD, which is the leading cause of blindness over the age of 65, is not as clear as that of RP. AMD is also a heterogeneous group of disorders, but the causes are proposed to be multifactorial, and the main known risk factors are both genetic and environmental ( 2, 5 ). There are two forms of AMD: the dry and the wet form. In the dry form, photoreceptors degenerate slowly