Retinal Degenerative Conditions
Certain retinal diseases are characterized by the degeneration of the retinal pigment epithelium (RPE), a pigmented layer of the retina, which in turn results in photoreceptor loss and ultimately leads to impaired vision. Degenerative diseases of the retina include Age-related Macular Degeneration (AMD), Stargardt's Macular Dystrophy (SMD) and other related diseases and conditions.
Age-Related Macular Degeneration (AMD)
AMD afflicts more than 30 million people worldwide and is the leading cause of blindness in people over 60 years of age in the United States. Dry AMD, which accounts for 90 percent of all cases, occurs when light-sensitive cells in the macula, which is located in the center of the retina, slowly break down, causing vision loss. As the disease progresses, patients can have difficulty reading and recognizing faces. There is currently no proven medical therapy for Dry AMD. To learn more about Dry AMD, please visit: http://www.nei.nih.gov/health/maculardegen/armd_facts.asp or http://www.macular.org
Stargardt's disease (also known as Stargardt's Macular Dystrophy, or SMD) is a form of juvenile macular degeneration that affects vision in children and young adults between the ages of six and 20. Stargardt's disease is an autosomal recessive disease that arises when both parents carry one mutated gene and one normal gene. The affected gene is called ABCA4 and is expressed in light-sensitive tissue. The ABCA4 protein is specifically expressed in rod and cone photoreceptors (the light-sensitive cells) and removes the toxic substances that are produced during phototransduction from photoreceptor cells. In Stargardt's patients, lipid-rich substances are not removed, leading to the accumulation of waste deposits in the RPE. These waste deposits, also called "lipofuscin," cause damage that leads to atrophy of the macula and RPE and ultimately to vision loss. To learn more about Stargardt's disease, please visit: http://ghr.nlm.nih.gov/gene/ABCA4 or http://www.macular.org