Juvenile macular dystrophy (sometimes called juvenile macular degeneration) is a group of inherited eye disorders that affects children and young adults. Juvenile macular dystrophy is different from age-related macular degeneration (AMD). AMD occurs as part of the body’s natural aging process, but juvenile macular dystrophy is an inherited condition (passed down from parents) that affects vision early in life.
The macula is a small area in the retina. It makes up only a small part of the retina, yet it is much more sensitive to detail than the rest of the retina. The macula gives you your central vision and allows you to see fine details clearly. The macula is what allows you to thread a needle, read small print, and read street signs.
The most common form of juvenile macular dystrophy is Stargardt disease. Other types of juvenile macular dystrophy include:
- Best’s disease (also called Best’s vitelliform retinal dystrophy)
- juvenile retinoschisis
All these diseases are rare and cause central vision loss.
What are the symptoms of juvenile macular dystrophy?
All forms of juvenile macular dystrophy share similar characteristics. They all cause problems with your central vision. Your central vision may be blurry, distorted or have dark areas. Side vision is usually not affected, but color perception may be affected in the later stages. Symptoms first appear in childhood or adolescence. These symptoms do not always affect each eye equally.
Some people with juvenile macular dystrophy keep useful vision into adulthood. For others, the disease progresses more rapidly. People with Best’s disease often have vision that is nearly normal for many decades. Many people may not be aware that they even have it. By contrast, Stargardt disease often results in vision of 20/200. This is the definition of legal blindness.
Juvenile retinoschisis also results in vision loss, ranging from 20/60 to 20/120. About half of people with the disease lose side vision. By age 60 or older, vision loss may reach 20/200.
Children with juvenile retinoschisis may also show signs of:
Who is at risk for juvenile macular dystrophy?
Juvenile macular dystrophy is an inherited genetic disorder. This means the disease passes from parent to child. Different types of the disease have different inheritance patterns.
For example, Stargardt disease is usually recessive. This means a child must inherit it from both parents for the disease to develop. Parents are most commonly “carriers” of the disease. This means they do not have the disease but can silently pass the diseases to their children.
Best’s disease is a dominant gene. This means a child only has to inherit the gene from one parent to develop the disease. When an affected person has children with an unaffected partner, there is a 50% (5 out of 10) chance a child will get the disease.
Juvenile retinoschisis is an X-linked disorder and overwhelmingly affects males. The genetic mutation that causes the disease is found on the X chromosome. Males inherit this chromosome from their mothers. (Fathers contribute the Y chromosome.)
Diagnosis
Your ophthalmologist will conduct a dilated eye examination to look at the retina. People with juvenile macular dystrophy have signs specific to their disorder.
People with Stargardt disease may have yellowish flecks in and under the macula. The flecks are deposits of lipofuscin, a fatty substance that builds up abnormally in patients with Stargardt disease.
Patients with Best’s disease have a yellow cyst that forms under the macula. The cyst may eventually rupture, spreading fluid and yellow deposits. These may harm the macula.
With juvenile retinoschisis, the retina splits into two layers, which affects the macula. The spaces between these layers can be filled with blisters. Blood vessels can leak into the vitreous, which is the fluid filling the eye. Juvenile retinoschisis can lead to retinal detachments.
Your ophthalmologist may perform a laser scan of the retina called OCT or fluorescein angiography to confirm the diagnosis. In this test, a dye is injected into your arm. The dye is photographed as it circulates through the blood vessels in your retina. Your ophthalmologist may also order an ERG (electroretinography) test. This test measures the electrical activity of the retina. Special labs now do genetic testing. They can find the exact gene that is causing the disease. This is important to know because different genes can cause the same appearance of the retina.
How is juvenile macular dystrophy treated?
There is no cure for juvenile macular dystrophy yet. But there are multiple gene therapy clinical trials underway. Gene therapy is a treatment that corrects the abnormal gene in the retina. These treatments may be able to slow progression of the disease and prevent vision loss.
Wearing sunglasses to protect the eyes from UV light and bright light is helpful. Low vision aids and mobility training can help people adjust to their vision loss. It is important to get genetic testing through your ophthalmologist. This tells you which specific gene is causing your macular dystrophy.