Stargardt’s Disease: Macular Degeneration – from a younger angle

While we usually consider macular degeneration as age related macular degeneration, a form of blindness affecting people, especially women over the age of 60, there is another, genetic form of this disease that affects children: Stargardt’s Disease   It can affect children all the way from very young to adolescence. Stargardt’s was named for the German ophthamologist, Karl Stargardt who described the disease in 1909. A late onset form, also genetically connected to Stargardt’s is called fundus flavimaculatus.
It is most often a genetically transmitted disease and considered autosomal recessive.  Autosomal recessive means that each parent carries one affected gene for the disease and one non-diseased gene. Neither parent will develop the disease.  A child of those parents has a 25% chance of inheriting both disease genes.  lt has a 25 percent chance because a child could inherit only one affected gene from either parent, or could inherit both non-affected genes, and thus remain with normal vision.  But if the child received both affected genes, then they will develop the disease.  It is important to note that each child of the parents carries the 25% risk, and not that 25% of their offspring will be affected.  But, of course, the parents may be unaware of their risk status and any symptoms, would not have any reason for genetic testing.  Until the child develops the disease, there is no way of knowing.
Juvenile macular degeneration begins the same as age related macular degeneration does with older people, with loss of central vision .  Blurry, wavy vision makes reading, watching television or recognizing faces challenging..  Symptoms begin slowly and progression is gradual.  It is the loss of photoreceptor cells  in the macula that causes the deterioration of clear central vision, and sensitivity to low light.  Later, it also contributes to the loss of color perception.  Peripheral or side vision is usually not affected.  Progression may be gradual, or move in stages, stabilizing for a while and then progressing again.  By age 50 vision will be severely impaired, reaching the level considered to be legal blindness.  When an ophthalmologist examines the eyes of a patient who has come in because of blurry vision or loss of central vision, they will see the small yellowish spots called drusen under the macula.  The drusen are actually bi-products of cellular processes triggered by the abnormal gene.
While there is no cure for this disease as yet, there is much research.  The gene that causes Stargardt’s was found in 1997.  Other genes have since been located that also affect the development of the disease. Molecular research is helping to understand how the gene functions and its role in other genetic and molecular interactions.  Through the development of this research, several very promising possibilities for treatment are emerging. Genetic research is rapidly advancing a study that will implant healthy versions of the gene into affected eyes.  Pharmacological interventions that regulate molecular interactions are also being developed for testing in clinical trials.  Several companies and research laboratories are exploring stem cell therapies for treatment.
Since there is no effective treatment or medical intervention at this time, patients are counseled to use assistive devices for low vision, such as a magnifying glass for reading .  Some magnifying glasses come with lights to better illuminate the page.  Computers can be adapted to accommodate some low vision problems, too.  Because bright sunlight is thought to contribute to the deterioration of the photo receptor cells affected by Stargardt’s, it is always recommended that patients wear sunglasses whenever they are outdoors and exposed to bright lights.  Quality of life is seriously affected for these people and additional training for people with low vision is also recommended.

Article by Marcia McCall

 
 
 

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