About Stargardt disease

Cause of Stargardt disease Diagnosis Symptoms

About

Stargardt disease is the most common form of inherited macular degeneration. Even so, misdiagnosis is common. Learning how the disease works and what to expect, from diagnosis to symptoms and managing the condition, can help inform conversations between healthcare providers and families about what to do next.

What is Stargardt disease?

Stargardt disease is a form of macular degeneration characterized by progressive, irreversible vision loss.

Stargardt disease is an inherited eye disease that leads to vision loss, usually starting in childhood or adolescence. Stargardt disease is the most common inherited eye disease, affecting about 30,000 people in the United States alone. As an inherited disease involving a gene mutation, Stargardt can affect multiple people within a family, such as siblings.

While there are a variety of resources dedicated to improving management of this disease, currently there are no approved treatments available.

mechanism of Disease

What causes
Stargardt disease?

As a genetic condition, Stargardt disease is linked to the mutation of a single gene, ABCA4.

ABCA4 is a protein found predominantly in the retina. ABCA4 plays a crucial role by transporting vitamin A and its byproducts between the cells of the retina.

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When a disease-causing mutation is present in the ABCA4 gene, it affects the ABCA4 transporter protein’s ability to function.

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Diagnosis

Misdiagnosis of Stargardt disease is common.

Typically, the onset of Stargardt disease happens in childhood; some people first begin noticing symptoms at a young age or in early adulthood. This is considered early–onset Stargardt disease. Early-onset forms of the disease may have a faster progression. Individuals diagnosed at a later age (45 or older) have a late-onset form of the condition, which may progress more slowly.

For early–onset cases, initial diagnosis can be difficult because the retina may appear normal, lacking the characteristic appearance of lesions seen in the retina of people with Stargardt. Early signs in patients with Stargardt may appear as bright “flecks” when assessed by fundus autofluorescence (FAF) imaging. Consequently, younger people with Stargardt are frequently misdiagnosed with other eye conditions or simply prescribed eyeglasses.

What I saw yesterday,
I cannot see today.

— 19–year–old with Stargardt disease

The following types of exams and/or tests can detect Stargardt disease for diagnosis:

Fundus autofluorescence (FAF) imaging is performed using a specialized camera called a fundus camera. During the exam, the patient’s eyes are dilated with eye drops to allow for a better view of the back of the eye, specifically the retina. The autofluorescence filter on the camera allows it to detect the natural fluorescence emitted by certain molecules, like lipofuscin. FAF imaging enables eye specialists to identify the characteristic signs associated with Stargardt disease, such as the bright flecks that denote lesions caused by lipofuscin, and areas of atrophy (black areas representing dead tissue).

Optical coherence tomography (OCT) is a non-invasive imaging test used to visualize the layers of the retina and measure their thickness. The images acquired by OCT can provide valuable information about the structure and health of the retina, as well as track disease progression by detecting abnormalities (such as thinning or thickening) or structural changes in the retinal pigment epithelium (RPE) and photoreceptor layers.

Electroretinography (ERG) is a procedure that assesses the retina’s responses in different types of light. During an ERG test, the patient’s eyes are dilated with eye drops and electrodes are placed on the surface of the eye or on the skin around the eye. The electrodes record electrical signals from the retina when it is exposed to flashes of light of varying intensities and wavelengths. These responses provide information about the function of the retina and can possibly identify abnormalities in the electrical responses of the retina.

Dilated eye exam, where eye drops are administered to dilate the pupil, allowing a physician to assess the retina for the presence of bright flecks or well-defined black areas associated with atrophy.

Genetic testing on blood samples detects the ABCA4 mutation and confirms Stargardt disease diagnosis.

Symptoms

Disease progression varies from person to person.

The leading symptoms for Stargardt disease are sensitivity to light and progressive loss of central vision, which can present as gray, black, or hazy spots, as well as blurring within the central vision. While symptoms don’t have to be present for diagnosis, it is often the presence of symptoms that leads people to seek an answer for what is happening to their vision.

Other symptoms include:

Inability to see clear, sharp definition (blurred vision)
Loss of night vision/vision in low or dim lighting
Changes in color perception
Blind spots in vision
Involuntary eye movements
Trouble adjusting to changes in light
Fatigue and/or headaches

An estimated 1,500 young people are diagnosed with Stargardt every year in the United States. Since Stargardt disease gets progressively worse as the lesions grow in size over time, testing and monitoring eye health is crucial, especially if changes with vision are noted. Although the rate of disease progression varies, half of people with Stargardt disease lose their sight within 3 years of initial symptoms, and the majority of people with Stargardt ultimately become legally blind by age 50.

There is significant variation in how people with Stargardt experience symptoms and how quickly their symptoms change over time. Supportive resources exist to assist with everything from daily life to classroom learning, work environments, and community connections.