Stargardt's Disease

There are no treatments for Stargardt's Disease

Facts:

Nutrients such as lutein, zeaxanthin and mesozeaxanthin may help slow the progression of Stargardt's Disease and/or prevent further vision loss.

Overview:

Stargardt's disease (also known as fundus flavimaculatus and Stargardt's macular dystrophy) is the most common form of inherited juvenile macular degeneration. Inherited as an autosomal recessive trait, it is a severe form of MD that begins in late childhood, leading to legal blindness. It is symptomatically similar to age-related macular degeneration, and may occur in one of every 20,000 children over the age of 6. It is usually diagnosed before the age of 20, when decreased central vision is first noticed. Boys and girls are equally affected by this condition. Over 25,000 Americans have Stargardt's disease.

Stargardt's disease causes a progressive loss of central vision. In the early stages, patients may have good visual acuity, but they may experience difficulty with reading and seeing in dim lighting.

In fundus photos, patients with early Stargardt's disease appear to have simple macular degeneration. Children with the disease typically begin experiencing dark adaptation problems and central vision loss between six and twelve years of age, but symptoms may also first appear in adulthood.

As the disease progresses, lipid rich deposits accumulate in the retinal pigment epithelium (RPE) layer beneath the macula. This "lipofuscin" appears as yellowish-tinted flecks. The RPE is a layer of cells that lies between the retina and the choroid, where it serves the purpose of nourishing the photoreceptor cells. In advanced Stargardt's disease, the buildup of lipofuscin causes atrophy of the macula and the underlying RPE. The progression of vision loss is variable and can start with a visual acuity of 20/40 and decrease rapidly (especially in children) to 20/200 (legal blindness). By age 50, approximately 50% of all of those studied in clinical trials had visual acuities of 20/200 to 20/400. In late stages of this disease, there may also be color vision impairment.

Supplementing with Vitamin A is considered contraindicated for Stargardt's Disease as some researchers believe gene mutations lead to abnormal synthesis of the vitamin in the eyes, resulting in increased loss of vision.

Symptoms:

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.

Causes:

Stargardt's disease is almost always inherited as an autosomal recessive disorder, with only ten percent of cases resulting from a dominant mode of inheritance. Autosomal recessive means that both parents are carriers, having one gene for the disease paired with one normal gene. As a consequence, each of their children has a 25 percent chance of inheriting the two copies of the Stargardt gene (one from each parent) needed to cause the disease. Carriers are unaffected because they have only one copy. At this time, it is impossible to determine who is a carrier for Stargardt's disease until after an affected child is diagnosed.

In 1997, researchers isolated the gene for Stargardt's disease. The ABCR gene produces a protein involved in energy transport to and from photoreceptor cells in the retina. Mutations in the ABCR gene, which cause Stargardt's disease, produce a dysfunctional protein that cannot perform its transport function. As a result, photoreceptor cells degenerate, and vision loss occurs. One of nineteen mutations in the gene (causing deletions and substitutions of amino acids) has been identified to cause Stargardt's disease. The non-functional ABCR protein permits the accumulation of yellow fatty material to accumulate in the retina. This material causes flecks and, ultimately, loss of vision. Further research is needed to find out how the mutated ABCR genes affect the biochemistry of the retina and lead to vision loss.

Conventional Treatment:

Currently, there is no effective treatment for Stargardt's disease.

Current research shows that patients with Stargardt's disease could slow its progression by wearing UV-protective sunglasses and avoiding exposure to bright light. Researchers have observed that mice which had a mutation of the ABCR gene, and which were reared in dark environments had virtually no lipofuscin deposits.

Since we consider most eye conditions to be a reflection of the health of the whole body, lifestyle choices and diet can play a major factor in getting and maintaining good vision. Below are some recommendations: