Due to it being an inherited retinal degeneration (IRD), it differs from Age-related Macular degeneration which arises as a result of the body’s ageing process.
Stargardt disease, Best disease and Juvenile Retinoschisis are the most common types of Juvenile Macular Degeneration and are caused by breakdown of the macula, the central region of the retina. The retina is the tissue layer at the back of the eye and contains rod and cone photoreceptor cells and cone cells. Rod cells are found along the outer edges of the retina and gives peripheral vision. Cone cells are most densely populated in the centre of the retina, perceive bright light (photopic vision) and give central vision.
The macula is very sensitive to detail and is required for sharp central vision and daily tasks, such as reading and driving. Juvenile Macular Degeneration causes a decline in detailed central vision, blurred and distorted vision whereby straight lines may appear wavy, increased sensitivity to light (photophobia) and night blindness.
The different forms of Juvenile Macular Degeneration are inherited in different ways, for example, Stargardt disease has an autosomal recessive pattern of inheritance and therefore requires two mutated copies ABCA4 gene for it to develop, with one copy from each parent.
In contrast, Best disease has an autosomal dominant pattern of inheritance, and only one copy of the BEST1 gene is necessary to cause the disease. You can learn more about the various forms of inheritance in our Genetics and Inheritance section.
Electroretinograms, optical coherence tomography (OCT) and fluorescence angiography tests are frequently used to diagnose Juvenile Macular Degeneration. Electroretinograms assess the integrity of the rod and cone photoreceptor cells and measure their electrical impulses in response to light exposure. OCT tests take high-resolution images of the different layers of the retina and search for any abnormalities. Fluorescence angiography involves injecting a dye into the person’s arm which travels through the person’s bloodstream and highlights any leakage in the blood vessels beneath the retina. Genetic tests are also a crucial part of the screening process as they can confirm a diagnosis by identifying mutations in specific genes which indicate which form of Juvenile Macular Degeneration a person lives with.
The different types of Juvenile Macular Degeneration are rare and cause central vision loss. Unfortunately, there is no treatment available to prevent vision loss caused by Juvenile Macular Degeneration. However, reducing exposure to UV light by wearing UV screening sunglasses and reducing vitamin A intake are two ways of managing Stargardt disease.
Regular eye exams are very important for people living with Juvenile Macular Degeneration as it is possible that they may develop other retinal conditions, for which there are treatments available.