What is Stargardt Disease?

Stargardt disease (STGD), which is a form of juvenile macular dystrophy, is a rare genetic eye disorder affecting the macula.¹ The macula is located at the center of the retina and is responsible for central vision (detailed vision). 

Stargardt disease causes the accumulation of fatty material (lipofuscin) on the macula, resulting in poor central vision. 

Stargardt disease affects about 1 in 10,000 people in the United States.² The disease is inherited, meaning it's passed down from parents to offspring. Vision loss often begins during childhood (between 6 and 12), but in some cases, it may occur during early adulthood. 

Early onset of Stargardt disease involves difficulty adjusting from dark to light or light to dark surroundings (delayed dark adaptation). The condition rarely affects peripheral (side) vision. However, it may cause color blindness.³

There is no known treatment for Stargardt disease, although vision rehabilitation may help maintain the remaining vision.

Symptoms of Stargardt Disease

The main symptom of Stargardt disease is loss of central vision. Other common symptoms include:

• Blurry/distorted vision
• Dark or hazy spots in the center of your vision
• Difficulty adjusting to different lighting conditions
• Color blindness 
• Poor night vision
• Sensitivity to light (photophobia)

Symptoms vary from person to person and range from mild to severe. Some people may lose their sight quicker than others. 

In this case, vision loss might accelerate at about 20/40 and deteriorate until it reaches around 20/200. Although central vision may be lost, side (peripheral) vision typically remains unchanged.

According to studies, people with Stargardt disease have an increased risk of depression and anxiety.⁴ This is due to the effects of poor visual acuity on psychosocial well-being.

How is Stargardt Disease Diagnosed?

Your doctor will diagnose Stargardt disease through a dilated eye exam. 

You'll sit on a reclining chair, and they will administer dilating eye drops to widen your pupils. They will then check for fatty yellow pigment on your macula (lipofuscin).

Tests

They may also perform the following tests:

• Fluorescein angiography. The doctor will inject a special dye known as fluorescein into your arm and observe as the blood with the dye circulates in the retina.⁷ A special camera takes pictures to identify any abnormalities. Someone with Stargardt disease will have a dark area within the retinal tissue.
• Electroretinography (ERG). An ERG test enables the doctor to check the retina's response to light. Abnormal response patterns may suggest the presence of Stargardt disease.
• Visual field test. This test assesses blind spots (scotomas), a common sign of eye disease.
• Color vision test. Your doctor may perform a color plate or hue test to determine your ability to see and differentiate colors.⁸
• Fundus photography. A fundus camera takes images of the retina to observe for abnormalities and the presence of yellowish flecks on the macula.⁹
• Optical coherence tomography (OCT). This test uses light waves to record detailed images of your retina. The images are then analyzed for any abnormalities that suggest macular degeneration.
• Genetic test. This test confirms the diagnosis of Stargardt disease and helps the doctor understand how the condition has been inherited and its implications on the family line.

Other

In addition, your eye doctor may detect signs of:

• Loss or wasting of the retinal pigment epithelium (atrophy)
• Retinal thinning
• Abnormal, involuntary eye movements
• Abnormal macular or foveal pigmentation

Diagnosis can be very stressful and emotional. As a result, some people may require professional counseling to understand their condition better and manage their feelings. 

What Causes Stargardt Disease?

Stargardt disease is caused by a mutation in the gene known as the ABCA4 gene.⁵ This mutation is also responsible for some retinal diseases like retinitis pigmentosa and age-related macular degeneration (AMD). 

In rare cases, changes in another gene known as the ELOVL4 may cause the condition. Both genes instruct the formation of special proteins that maintain the health of photoreceptor cells.

Photoreceptor cells (rods and cones) transform light signals into electrical signals that are transmitted to the brain for interpretation. This process is known as phototransduction. The ABCA4 protein is responsible for removing toxic material from the photoreceptor cells produced during phototransduction.⁶

If the ABCA4 gene mutates, it prevents the removal of toxins from the photoreceptor cells. This results in lipofuscin (fatty material) buildup in the macula and surrounding retinal cells. Lipofuscin accumulation causes degeneration of photoreceptor cells and progressive vision loss.

Similarly, the mutated ELOVL4 gene results in the accumulation of ELOVL4 protein clumps, which cause retinal cell death, a characteristic of Stargardt disease.

Treatment Options & Outlook

Currently, there is no known treatment for Stargardt macular dystrophy. However, you can do the following to slow down vision loss:

• Wear protective gear like hats and sunglasses to protect your eyes from bright sunlight.
• Take vitamin A supplements, but only in recommended doses as excess can cause more harm than good to the retina.
• Avoid smoking or exposure to second-hand smoke to slow down vision loss.
• Use low vision aids, including magnifiers, bifocal glasses, electronic audiobooks, and glasses with microscopic lenses.
• Limit alcohol intake
• Eat a lot of fruits and green vegetables
• Invest in vision rehabilitation programs to help you manage disease progress.

Scientists are trying to find more effective ways of treating Stargardt disease. Promising clinical trials include gene therapy and drug therapy. 

For example, scientists are investigating a popular diabetes drug known as metformin which has the potential to slow down vision loss.¹⁰ Stem cell therapy has also been suggested as a potential remedy for Stargardt disease. 

Can Stargardt Disease Be Prevented?

Stargardt macular degeneration cannot be prevented. 

However, observing some lifestyle habits, like quitting smoking, limiting alcohol intake, avoiding excess vitamin A, and protecting your eyes against UV rays, can help slow disease progression.

Engaging a professional counselor can also help people with Stargardt disease understand the genetics of the disease and the risk of passing it down to future offspring.

Summary

• Stargardt disease (STGD), a form of juvenile macular dystrophy, is a rare genetic condition characterized by macular degeneration
• The main symptoms of STGD are progressive vision loss, blurry vision, photophobia, color blindness, and retinal thinning, among others
• Diagnosis of Stargardt disease is through a dilated eye exam to observe yellowish deposits in the macula known as lipofuscin
• Other tests may include fluorescein angiography, electroretinography (ERG), visual field testing, color vision testing, fundus photography OCT, and genetic testing
• There is no known treatment or preventive measures for Stargardt disease, but some lifestyle habits and rehabilitation can help slow disease progression