One very common symptom of concussion is blurred vision. It just also happens to be that astigmatism causes blurred vision too. Could these two be related? Can a concussion lead to the development of astigmatism in your vision?
Fortunately, the only thing astigmatism has in common with a concussion is that they can both cause blurred vision. Astigmatism is created completely separately than how a concussion affects your vision. You cannot get astigmatism from a concussion.
Astigmatism really has an anatomical basis mostly in the cornea. Concussions cause short term neurologic problems and affect movements and focusing of the eye. So let's learn more on how the two are different.
What Is Astigmatism?
In a perfect world, your cornea would be shaped like a perfect dome and light would be focused perfectly on your retina. Some people are living the dream in this perfect world but for most others the cornea isn't a perfect dome. For others, the cornea takes on a more “football-like" shape. One direction of the cornea is steeper than the other direction of the cornea.
As a result, not all light is focused in the same place. Light that passes through the steep part of the cornea focuses at a different spot than light that passes through the flat part of the cornea. This creates blurry vision. This is what astigmatism is.
Correcting Astigmatism
To fix astigmatism, you simply have to make the flat part and the steep part of the cornea match. This can be achieved with glasses. By using a “football-shaped" or more accurately a cylinder lens, one can change the way light hits the cornea. By matching up the steep part of the cornea and flat part of the cornea, you can get light to focus at the same spot. This corrects that blurry vision from astigmatism
Where Does Astigmatism Come From
So if astigmatism doesn't come from concussions, where does it come from? In fact, for most people, you're either born to have astigmatism or you are not. There are a few factors which can influence the development of astigmatism, such as genetics and ethnicity, but your anatomy of your eye, such as how your eyelids sit against your cornea determine whether you have astigmatism or not.
There are a few ways you CAN acquire astigmatism
- In a condition called keratoconus, the cornea can weaken over time. As the cornea weakens, it can change shape and create astigmatism in your vision.
- Any change in eyelid position can cause changes to your astigmatism. This includes getting a bump or stye on the eyelid or if you need eyelid surgery for any reason.
- Surgery on the eye has a potential to create large amounts of astigmatism. This is especially the case for surgeries involving the cornea.
The last category (surgery) includes any repairs needed after an injury to the eye. If you get hit in the head and there is an injury to the cornea that must be repaired with stitches, then you can end up with astigmatism from that injury. This is perhaps the one situation in which an injury can lead to a concussion AND astigmatism (but the concussion didn't cause the astigmatism).
What Causes A Concussion?
Within our head is our brain. But our brain isn't firmly attached inside our head; it is instead “floating" around in a special fluid (the cerebrospinal fluid). This isn't normally a problem; in fact, this is normally a benefit. The fluid acts a shock absorber and helps to provide nutrients to the brain.
When we get hit in the head, however, the brain can move around in the head too much. The force of the blow affects the head and the fluid and brain differently. This can cause the brain to bounce and / or twist inside the skull.
These blows to the brain can cause brain cells to become injured and cause many short-term deficits. This can cause a variety of symptoms.
You can develop problems with thinking and coordination. This can lead to confusion, inability to remember being hit in the head, and even temporarily loss of consciousness. Or it may simply cause you to feel foggy or “off".
You can also have problems with coordination. You can develop dizziness or balance problems which causes you to have less control over your movements. You may stumble around.
Being hit in the head can also cause a bad headache, nausea and vomiting and sensitivity to light and sound.
Effect Of Concussion On The Eyes
The eyes are controlled quite heavily by the brain. As a result, there are many eye symptoms that can be observed after a concussion. And these eye symptoms can be quite common.
In fact, many of these eye issues are tested when screening for any signs of concussion.
Concussions dramatically affect the nerves which control how the eyes move around and work together:
- The eyes can have a hard time focusing up close. This can cause blurry vision when trying to read or work on the computer. For some individuals who are far-sighted (but typically able to focus through this prescription), this can also cause their distance vision to be blurry.
- The eyes can have a hard time working and moving together when looking up close. This can cause double vision when attempting to read.
- The eyes can have a hard time moving around in general. This can create difficulty when trying to track something (such as following and reading text on a page) or this can create double vision.
- The eyes can have trouble staying aligned causing one eye to be deviated - commonly called lazy eye or known as strabismus. This will also create double vision.
- While not exactly the eyes, but related, one can overall have much more sensitivity to bright lights.
This blurred vision, double vision and trouble focusing can cause headaches and fatigue as you struggle to work up close. But fortunately, these changes aren't permanent (but they still can last quite a long time).
Summary
Astigmatism and concussions are two separate entities. While you can have symptoms of blurred vision from a concussion, you don't have to worry about a concussion causing you to develop astigmatism now or in the future.
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