Generally, macular degeneration is associated with older age, but an inherited, juvenile form known as Stargardt disease affects children and young adults.
A genetic mutation that causes protein to block the passage of nutrients and waste, to and from the macula. The macula (the center part of the retina), and its photoreceptor cells are damaged as a result of this.
Stargardt disease, also known as fundus flavimaculatus, Stargardt Macular Dystrophy, or Juvenile Macular Degeneration, affects about one in every 10,000 people; hence considered a rare eye disease.
Characterized by central vision loss at an early age, it’s a form of inherited disease that causes the light-sensitive cells in the inner back of the eye to deteriorate, specifically in the macula, responsible for our central vision. Central vision loss is apparent, but peripheral vision is usually retained.
Stargardt disease is diagnosed when the presence of small, yellowish spots are seen on the macula. These deteriorated tissues have sloughed off from the colored or outer layer of the retina. The progression of this disease increases over time, making Stargardt a progressive eye disease.
How Does Stargardt Disease Cause Low Vision in Children
The most common symptoms you’ll hear from a child are:
- Blurry vision
- Dark spots when looking at a screen or reading a book
- Trouble seeing colors
- Difficulty in recognizing familiar faces
These aren’t to be taken lightly. All these symptoms can indicate an apparent eye disease and Stargardt is among them.
As a congenital disease, it affects children or adults, often at the age of 6 to 12, and is usually present at birth. This rare eye disease causes progressive vision loss and may lead to a point of legal blindness, with time.
The struggle of dealing with Stargardt can cause children to feel disconnected, and embarrassed or lead to depression.
Why Does Stargardt Disease Affect Children?
Stargardt, like macular degeneration, refers to a damaged macula. Because the macula is in charge of our central vision and color vision, when damaged, causes poor eyesight, image distortion, and blurry spots in the central vision.
Why is Stargardt disease only diagnosed in children and young adults?
As an inherited eye disease, Stargardt’s progress affects the children only when both parents carry mutations of the gene associated with vitamin A processing in the eye.
The mutation happens in the ABCA4 gene, which is responsible for encoding proteins that travel back and forth from the photo receptors. This mutation affects the processing of vitamin A and results in the accumulation of toxic dimers of vitamin A. The result? The retinal pigment epithelium and photo receptors begin to die.
Why?
Because their everyday lives are affected by central vision loss, which leads to problems such as reading text at the center of the vision, and distinguishing between basic colors.
How Is the Gene Transferred?
Stargardt disease is inherited in an autosomal recessive manner. It means one mutated copy of the gene from each parent should be present, for the individual to be affected.
Hence, making them carriers, yet they may not have any signs or symptoms of Stargardt’s progress. When two carriers of recessive conditions have children, each child has a:
- 25 percent chance to be affected
- 50 percent chance to be unaffected but become a carrier like the parents
- 25 percent chance to be unaffected and not become a carrier
As a carrier of Stargardt disease, one mutated copy of the gene will always be passed to each of the children. Hence, each child will at least be a carrier even if no symptoms are found.
What Does the Vision Look Like with Stargardt Disease?
Stargardt’s progress leads to the degeneration of photo receptors in the retina, mostly in the middle; causing the central vision to recede. The peripheral vision is preserved (in most cases).
However, Stargardt can be different for everyone and can be diagnosed at different ages. Yet, as a progressive vision loss disease, it worsens with age. In some cases, it stabilizes at a certain stage, and in others, it can lead to legal blindness.
People with Stargardt disease are asked quite frequently about how they see. It’s not easy to explain it to someone with normal vision, and it would definitely be hard to imagine.
We’ll give a few examples of what a person with Stargardt disease usually sees.
Blind Spots
We all have blind spots, where a person’s view is obstructed, as these areas are insensitive to light.
For a person with Stargardt disease, these blind spots can be many or few and of a larger size. It may come off as something scary, but it usually isn’t.
Let’s take an example. A person with Stargardt looks at a white table with a mug, a cell phone, and a pencil on it. With the help of peripheral vision, he will be able to see the table in front of him and maybe even the mug that is to the left of the field of vision. However, the cell phone and the pencil, in the middle, will not be visible, which makes the brain think there is nothing there. But if the person moves their head to the right, these objects will appear in the peripheral view, but the rest will disappear.
Difficulty Reading
Reading continuous sentences becomes difficult when blind spots emerge in the central vision, making it difficult to focus on the text. Even with large writing, just the first few letters are visible, and the user may have to constantly shift their head back and forth to see the remainder.
This would require extreme concentration, and after some time, the eyes start to hurt.
Missed Details
Details including people’s faces, small objects held in a hand, and how many fingers someone is holding up become unrecognizable in most cases of Stargardt disease.
People around them are seen as silhouettes, and to recognize them, good lighting as well as other known factors like height, clothes, and voices are used.
For example, a child with Stargardt would have tremendous difficulty differentiating between people in a large group.
Orientation
The directions and surroundings disorient a person with Stargardt. Walking around a place with too many buildings, signs, billboards, etc. causes confusion as most of the view is obstructed. Due to these distractions, a person with the disease could end up walking straight into a streetlamp.
Light Sensitivity
Photophobia is common with Stargardt. Direct sunlight may cause discomfort, which means wearing dark sunglasses would help.
People with Stargardt find it discomforting to be in a dark room with windows and other bright light sources, as adjusting vision from a highly-lit area to a low-lit area is problematic.
Colors
Color recognition may not sound like a big issue, but it has its side effects. People with Stargardt have trouble distinguishing between colors of similar shades. Colors with similar dark hues or undertones are difficult to distinguish. For example, colors like black, brown, dark blue, dark green, and dark purple may seem exactly the same.
So, it wouldn’t come as a surprise when a person with Stargardt disease reaches for their cell phone and accidentally spills the mug, because the blind spot obstructed the view of the mug.
Stargardt’s Progress
Stargardt disease and fundus flavimaculatus are different stages of the same disease.
Vision loss from Stargardt generally shows up in the first 20 years, particularly in early childhood. However it is not easy to pinpoint the exact moment of retinal damage and how fast it will progress.
On the other hand, fundus flavimaculatus is linked to Stargardt and is considered its subset. Fundus flavimaculatus has a later eye disease onset and slower visual deterioration, which makes it a milder condition.
If you look at the fundus photographs of both diseases, you’ll see that fundus flavimaculatus involves a larger portion of the retina, where the flecks are more scattered and extend to the mid periphery. Yet, the macula is less involved, which allows better visual performance. With Stargardt, the flecks are seen on the macula, damaging the central vision the most.
Both these diseases have their characteristics, and vision loss is something anyone with such a disease would want to avoid.
There are ways to overcome low vision caused by Stargardt’s progress. With no proper Stargardt cure in place, low vision aids like the IrisVision headset have transformed the lives of people affected by low vision and legal blindness. It enhances and improves the visual acuity of the eye and restores vision by leveraging the leftover vision of an individual suffering from any form of rare eye disease. The options are endless and the way of life exponentially improved because of its ability to restore and enhance vision.
