Stargardt disease: symptoms, genetics, diagnosis and living with it

The macula is the small central area of the retina where light entering the eye is focused. RNIB explains that it holds a high concentration of cone cells, which work best in bright light and allow you to see fine detail, such as reading and watching television, as well as colour. In Stargardt disease the macula gradually wastes away.

The Macular Society says the condition is caused by a tiny fault in a single gene. A build-up of a waste material called lipofuscin affects the retinal pigment epithelium, an important layer of the retina, and RNIB says it can eventually damage the cone cells in the macula. The condition is also known as juvenile macular dystrophy, Stargardt macular dystrophy and fundus flavimaculatus.

RNIB says that at first Stargardt disease can make vision unclear or blurry, and things may appear distorted or wavy. The Macular Society says people may have good vision in the early stages but experience the following.

• Difficulty reading or seeing in dim light.

• Blurriness and distortion of vision.

• Difficulty adapting from dark to light, or light to dark, surroundings.

• Problems with central detail, such as recognising faces.

• Changes in colour perception.

• Glare and sensitivity to bright light.

• After several years, a missing patch in the centre of vision that does not move.

The Macular Society says progression varies between people. At first changes to vision are often quite slow, but once vision has begun to change sight loss can become more rapid. Eventually most people end up with very low vision that cannot be corrected with glasses, contact lenses or surgery. Even so, it stresses that in most cases people do not lose all their sight, because the condition usually affects central vision only.

RNIB notes that some forms affect peripheral vision, but for most people it is central vision that is affected, and because peripheral vision is used when moving around, most people can continue getting out and about independently.

RNIB says the genes associated with Stargardt disease are ABCA4, ELOVL4 and PROM1, and that ABCA4 is responsible for most cases. Variants in ABCA4 are inherited in an autosomal recessive pattern: both parents carry a variant gene, and are usually unaffected themselves, and a child who receives both copies has the condition. The Macular Society says with recessive inheritance there is a 25% (1 in 4) chance of each child inheriting the condition.

A smaller number of cases are caused by the ELOVL4 gene and inherited in a dominant pattern, where a parent with the condition has a 50% chance of passing it to each child. Families affected by an inherited eye condition are usually offered genetic counselling, which explains the chances in the family and the options available.

The Macular Society explains that an eye care professional can diagnose Stargardt disease by examining the retina, where lipofuscin deposits appear as yellowish flecks in the macula, often forming a ring. A standard eye chart and other tests may be used to assess vision loss.

Those tests can include visual field testing, electroretinography (ERG) that measures electrical signals from the retina, optical coherence tomography (OCT) scans, autofluorescence imaging with a special camera and genetic testing. Diagnosis is typically made by a hospital eye service or a specialist inherited retinal disease service after referral from an optometrist or GP.

There is currently no treatment for Stargardt disease, according to the Macular Society, but a great deal of research is going on. The main areas are new medicines to reduce the build-up of harmful waste and protect light-sensitive cells, gene therapy that aims to treat the underlying ABCA4 fault, and stem cell therapy. The medicines are designed to slow vision loss rather than cure the condition.

The Macular Society lists general eye-care measures. It says people with Stargardt disease cannot process vitamin A properly, so it is important to avoid getting too much; to avoid bright light, which may make vision worsen faster; to visit an optician at least every two years; not to smoke; to maintain a healthy weight and blood pressure; and to wear lenses that block UV light and a wide-brimmed hat or visor in bright sunlight.

The Macular Society says you can learn to use your side vision more effectively, a skill called eccentric viewing, and that practical changes help people stay independent: brighter lighting in key areas, large print books, bigger text settings on devices and sitting closer to the television. A low vision assessment can identify what works best. For light sensitivity it suggests 100% UV-protective sunglasses, tinted lenses, a hat with a brim and adjusting screen brightness.

Children with sight loss are eligible for special educational needs support in school, and in higher education the Disabled Students' Allowance can fund equipment and support. At work, employers must make reasonable adjustments, such as extra time, large print materials, better lighting, screen readers or other low vision aids.

NHS care is through an optometrist or GP referral to the hospital eye service, which may arrange specialist imaging and genetic testing, with low vision services and rehabilitation officers available through hospitals and local councils. Charities such as the Macular Society and RNIB provide information and support groups.

Private ophthalmology can give quicker access to imaging or a second opinion, but few treatments are available either way. Ask whether a service has experience of inherited retinal disease and whether it can refer to research studies or clinical trials.