One of the most complained about things in eyecare, especially in mid-aged patients, is having floaters in your vision. But how can you differentiate a harmless floater from something serious?
What is an Eye Floater?
A “floater” is a term used to describe a little black, grey, or whitish colored “squiggle” moving across your vision. They are most often noticed when looking up at a blue sky, when driving, or when looking at a solid white background.
Sometimes floaters appear as multiples, and sometimes they appear as a single little dot.
Typically floaters come and go, but will usually be seen in the same area of your vision and of the same shape and size.
What is an Eye Flash?
A “flash” is a term used to describe when you see flashes of light that are not actually there—it may look like someone just took your picture and blind you for a second or two before you vision returns to normal.
Flashes tend to occur when a person quickly looks in an extreme direction—to the far right, far left, straight up, straight down, etc.
Flashes can occur singularly or can occur as many back-to-back.
What causes Eye Flashes and Eye Floaters?
To best understand why flashes and floaters occur, a quick lesson in eye anatomy is required.
There are 3 main structures of the eye—the cornea, the lens, and the retina. The cornea is the very front of the eye, the lens is the middle structure, and the retina is the back of the eye.
The retina is essentially the most important part of the eye—it contains special cells called photoreceptors that are responsible for detecting light and transmitting imaging information to the brain.
If you take a moment to feel your eye, you can tell that it is filled with some kind of fluid to keep it turgid and help it keep its shape. There are actually two types of fluid—the aqueous humor and the vitreous humor.
The aqueous humor is found between the cornea and the lens. The vitreous humor is found between the lens and the retina.
In terms of flashes and floaters, the vitreous humor is the culprit of the issue.
To further understand the anatomy, let’s think of the eye being a water balloon filled with jello instead of water. The retina is the rubber part of the balloon and the vitreous humor is the jello.
With the normal aging process, the jello inside the balloon starts to break down into water and clumps of sugar. As it breaks down, the shape of it changes—instead of being perfectly round and conformed to touch every edge of the balloon, it becomes shriveled up in some areas with water pockets in others.
In the eye, this occurs naturally with the vitreous humor—the vitreous breaks down into collagen fibers and water pockets. Floaters are the little fibers floating around in the pockets of water—just like clumps of sugar would float around in our separating jello.
The problem with the eye, however, is that everything from the front of the eye to the back of the eye must be clear. If anything in front of the retina is opaque, the retina detects that point as an absence of light and sends a signal to the brain that there is an object there blocking light from reaching the photoreceptors.
The retina cannot differentiate between the collagen fibril within the eye itself, and an object outside of the eye, so we see a little “floater” floating around.
Now, going back to our example, let’s say when the jello (vitreous humor) started to separate and shrivel up, it did not just make a clean break from the rubber (retina). The jello has been sitting within the balloon for so long the two have a strong bond and do not want to let go of one another. As a result, the jello tugs at the balloon, tenting it up in the locations of traction (or locations of extra stickiness).
This is what causes “flashes” of light. The vitreous tugs at the retina and cannot just separate or break off. Instead, it tugs and pulls at it in an attempt to separate, activating the photoreceptors in that area. The photoreceptors think the eye is detecting enormous amounts of light in that particular area, and signals to the brain that a flash of light is being seen. But, in reality the photoreceptors are just being activated as a result of the vitreous humor tugging on the retina.
Both flashes and floaters can be, and usually are, totally normal and do not indicate any major problem, especially when they are few in number and have not changed over time. However, in about 10% of cases they can indicate something much more serious.
When to Call your Eye Doctor when you have Eye Floaters or Flashes
In some circumstances, the vitreous and the retina never “let go” of each other, and the retina literally tears off and moves inward with the vitreous. In our jello example, think about it as the jello being so strong it rips the balloon, and now the balloon is broken and flapping as two little rubber pieces in the wind.
This is what happens to the retina and is called a retinal detachment.
Retinal detachments are serious and treatment needs to be initiated with 12-24 hours in order to save vision.
Signs that you may have a retinal detachment instead of just normal flashes and floaters include:
-A sudden increase in flashes and floaters
-A sudden, painless loss of vision
-A “veil” or “curtain” over your vision (this is literally a piece of the retina flapping around in the vitreous humor)
If you experience any of these signs, you should call your eye doctor ASAP.
It should also be noted that flashes tend to be associated more often with retinal detachments than floaters, as flashes indicate traction on the retina. Many flashes in a row should be taken seriously and you should call your eye doctor ASAP so he or she can evaluate you with a dilation exam to ensure the retina is still intact and initiate treatment quickly if needed.
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