Juvenile macular degeneration refers to several and rare inherited retinal disorders. It is among the genetic diseases that lead to macular degeneration. JMD disorders cause loss of sight in childhood or early adulthood. There are other forms of vision loss linked to the disorders that occur in adulthood.
Juvenile macular degeneration causes progressive degeneration or damage to the macula. The macula is located in the middle of the retina and controls the fine vision details. In most cases, loss of vision will progress over time upto 20/200 (normal vision is 20/20) or worse. Vision 20/200 is the legal definition of blindness.
Stargardt disease is the most common form of the disease. Estimates show that one in eight to ten thousand (1/8-10 000) people suffer from Stargardt disease. The other types of JMD are extremely rare.
Also Known As
- Stargardt macular dystrophy
- Fundus flavimaculatus
- Stargardt disease
- Best’s disease also referred to as Best’s vitelliform retinal dystrophy
- Juvenile retinoschisis
Causes and Risk Factors
Juvenile macular degeneration is linked with genetic defects that cause the malfunction and death of the cells responsible for central vision. Often, family members are not aware they have it.
Different forms of the disease have different inheritance patterns. Stargardt disease has to be inherited from both parents for it to develop. It is a recessive gene. Best’s disease can develop if the child inherits it from one of the parents, i.e. it is a dominant gene.
Juvenile retinoschisis is associated with a genetic mutation of the X-chromosome. In most cases, the defective X-chromosome is inherited from the mother and affects males. It can also be passed on from the father to the daughter. Women who inherit the gene become carriers.
Signs & Symptoms
Symptoms of the disorder first appear in childhood and early adulthood. JMD symptoms include:
- Change of central vision
- Blurred vision
- Distorted vision
- Difficulty reading
- Loss of color vision in later stages
- Loss of side vision
- Misaligned eyes
- Involuntary eye movement.
The symptoms may not affect both eyes equally.
Often, Stargardt disease leads to 20/200 vision. In Juvenile retinoschisis, the loss of vision ranges from 20/60 to 20/120. Patients over 60 may experience legal blindness, i.e. 20/200 vision.
The eye care professional diagnoses juvenile macular degeneration through an eye exam. It may include:
- Visual field testing
- Dilated eye test
- ERG (Electroretinography) test
- Fundus photography
- Color testing
He/she may also conduct a fluorescein angiography for a definite diagnosis.
Treatment is aimed at maintaining vision.
There is no standard treatment for the eye condition.
The eye doctor may recommend using UV protective sunglasses when outdoors. It protects the patient’s eyes from bright light and UV rays. The doctor may also restrict supplements with more than the recommended vitamin A daily allowance. Both measures seek to prevent an increase in the rate of degeneration.
At times, patients with Stargardt disease and Best’s disease develop new blood vessels to the macula. The new blood vessels may develop leaks and bleed like in wet age-related macular degeneration (AMD).
The doctor may use injections with antibodies to block the vascular endothelial growth factor (VEGF) to stop the bleeding and leakage of fluids into the macula. This is known as anti-VEGF therapy.
Laser treatment may aid in severe cases of bleeding and fluid leakage.
Surgery can also repair detached retinas.
At times, juvenile retinoschisis can result in retinal detachments.
The onset and progression of JMD varies from person to person. In some cases, the disease sets in early in life and the patients experience a rapid loss of sight. In other cases, loss of vision may progress slowly in the beginning and then worsen at a fast rate until it levels.
Also, some people with JMD keep sufficient vision into adulthood. Often, people with Best’s disease have almost normal vision for many decades.
Unfortunately, there is no cure for juvenile macular degeneration. There is also no therapy to slow its progression.
Visual aids and vision rehabilitation therapy are among the tools that can assist young people with vision loss to remain independent and active.
Researchers continue to look for ways to prevent JMD.
Genetic testing and counseling can assist in educating parents about the disorders. People at risk should avoid smoking and second-hand cigarette smoke.