Stargardt disease is a genetic eye disorder that causes progressive vision loss. This disorder affects the retina, the specialized light-sensitive tissue that lines the back of the eye. Specifically, Stargardt macular degeneration affects a small area near the center of the retina called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. In most people with Stargardt macular degeneration, a fatty yellow pigment (lipofuscin) builds up in cells underlying the macula. Over time, the abnormal accumulation of this substance can damage cells that are critical for clear central vision.
Signs and symptoms mentioned in various sources for Stargardt Disease includes
- progressive central vision loss
- colour vision abnormalities
- problems with night vision
The signs and symptoms of Stargardt macular degeneration typically appear in late childhood to early adulthood and worsen over time.
In most cases, Stargardt macular degeneration is caused by mutations in the ABCA4 gene. Less often, mutations in the ELOVL4 gene cause this condition.(A rarer disease called autosomal dominant Stargardt-like macular dystrophy, similar to Stargardt, is caused by the gene ELOVL4.) The ABCA4 and ELOVL4 genes provide instructions for making proteins that are found in light-sensing (photoreceptor) cells in the retina.
The ABCA4 protein transports potentially toxic substances out of photoreceptor cells. These substances form after phototransduction, the process by which light entering the eye is converted into electrical signals that are transmitted to the brain. Mutations in the ABCA4 gene prevent the ABCA4 protein from removing toxic byproducts from photoreceptor cells. These toxic substances build up and form lipofuscin in the photoreceptor cells and the surrounding cells of the retina, eventually causing cell death. Loss of cells in the retina causes the progressive vision loss characteristic of Stargardt macular degeneration.
The ELOVL4 protein plays a role in making a group of fats called very long-chain fatty acids. The ELOVL4 protein is primarily active (expressed) in the retina, but is also expressed in the brain and skin. The function of very long-chain fatty acids within the retina is unknown. Mutations in the ELOVL4 gene lead to the formation of ELOVL4 protein clumps (aggregates) that build up and may interfere with retinal cell functions, ultimately leading to cell death.
Prognosis of Stargardt disease 1: slowly progressing condition
Stargardt disease, like other forms of macular degeneration, does not have a cure yet. It is sometimes treated with intraocular injections of anti-VEGF drugs, similar to "wet" Age-related Macular Degeneration treatments, if there is the proliferation or leakage of blood vessels. Nutrition and eye protection (especially sunglasses which block UV A and B and blue light) may have a beneficial effect on the progression of this disease. When vision begins to change – whether that is in the teen years or the twenties – vision aids become essential, maximizing the use of peripheral vision.