Stargardt's Disease

Stargardt's Disease (fundus flavimaculatus, Stargardt's macular dystrophy) is a common type of macular degeneration affecting young people. It arises from an inherited recessive gene and manifests as a very severe type of macular degeneration beginning in late childhood and resulting in becoming legally blind.

The symptoms of Stargardt's are similar to those of age-related macular degeneration (ARMD). It is diagnosed in 1 in 20,000 children over 6, usually identified before age 20. The first symptom is decreased vision.

Early Stage

Stargardt's disease results in progressive central vision loss, first reported as difficulty in reading and seeing in low light situations, although vision is generally good. These problems are generally noticed between ages 6 to 12, though the symptoms may also arise as an adult.

Disease Progression

With further progression, oily deposits begin to accumulate in the layer of tissue comprising the retinal pigment layer of cells (RPE) which is the layer behind the macula. The RPE is a layer lying between the retina and the choroid, providing nourishment to photoreceptor cells. These deposits, called "lipofuscin", look like yellowish-tinted specks. The accumulation of lipofuscin eventually causes wasting away of the macula and the RPE. How fast and to what degree vision is lost varies, especially in children. It can begin with 20/40 vision and rapidly decrease to 20/200 which is the level for legal blindness. Color vision may also be impaired in advanced Stargardt's. By age 50, about half of all of patients assessed in clinical trials had visual acuities of 20/200 to 20/400.

The main signs and symptoms are loss of visual acuity or sharpness of vision, decreased color vision and small blind spots.

Other symptoms may include blurriness and visual distortion, difficulty adapting to the dark after sunlight exposure, and/or light sensitivity.

In more severe stages of vision loss, patients may experience Phantom vision or visual hallucinations. These episodes are not usually related to underlying psychiatric problems, but rather are normal attempt by the brain to make sense of impaired sensory information. The brain may embellish the image making it very real just as it does in our dreams.

Stargardt's disease nearly always arises from an inherited recessive gene. This means that both parents carry the gene. Each of their children has a 25% chance of inheriting a gene from each parent. Parents might not themselves have Stargardt's since they might have only one gene and two are required to cause Stargardt's.

In 1997, researchers identified the specific gene tied to Stargardt's. It is one of 19 known mutations of the ABCR gene which produces a protein required for energy transport to and from photoreceptor cells in the retina. The mutations cause a non-functioning protein that is unable perform its transport function. The dysfunctional ABCR protein allows fatty deposits to accumulate in the retina's RPE layer. The end result is that photoreceptor cells degrade with resulting vision loss.

Currently, there is no effective treatment for Stargardt's disease. Research does suggest that supplementation with betacarotene and Vitamin A should be avoided as those with Stargardt's have difficulty breaking down this vitamin in the eyes.

This can result in additional toxicity to the retina.

Current research shows that UV-protective sunglasses can help slow the progression of Stargardt's disease. Researchers have observed that mice with a mutation of their ABCR gene who were reared in dark environments had almost no lipofuscin deposits. Researchers are investigating whether injection of human embryonic stem cells has some benefit.

In 2010 some research indicated that stem cell therapy may possibly be helpful for Stargardt's disease. In addition, some research on macular degeneration may be relevant.