Have you ever been driving and getting ready to switch lanes, thinking it’s clear, and you turn your head to double-check and realize there’s actually a car driving in the lane next to you? That’s one example of our blind spot, also called the scotoma.
This is completely normal and usually not something to worry about.
What is the purpose of a blind spot in the eye?
The blind spot is where the optic nerve and blood vessels leave the eyeball. The optic nerve is connected to the brain. It carries images to the brain, where they’re processed. This is how we know what we’re seeing. Our eyes see the object or image, and our brain interprets it. Our brains typically fill in any information we need based on the images surrounding our blind spot, so we don’t usually notice it.
Side-view mirrors on cars are a good example of how we compensate for our blind spots. Many times, cars traveling next to us fall in our blind spot, and the side-view mirrors give us a different angle to view the same area. They allow us to “see” in our blind spot.
A recent study found that certain eye exercises can help reduce the size of the blind spot, but more research is needed. If one eye is trained, these gains did not transfer to the other untrained eye.
What causes a blind spot in the eye?
Each of our eyes has a tiny functional blind spot about the size of a pinhead. In this tiny area, where the optic nerve passes through the surface of the retina, there are no photoreceptors. Since there are no photoreceptor cells detecting light, it creates a blind spot. Without photoreceptor cells, the eye cannot send any messages about the image to the brain, which usually interprets the image for us.
Typically, the blind spot is nothing to worry about. It occurs naturally and serves a purpose. However, if you notice that your blind spot is getting larger, or if you have other blind spots in your field of vision, or floating blind spots, these are not normal, and should be evaluated by an eye doctor.
How to test your blind spot
Wondering where your blind spot is? In your left eye, it’s approximately 15 degrees to the left of your central vision (two hand widths, if sticking out your arm). In your right eye, it’s about 15 degrees to the right of your central vision.
In order to find the blind spot in your eye, here’s a simple test you can do:
- On a piece of paper, make a small dot with a black marker.
- About six to eight inches to the right of the dot, make a small plus sign (+).
- With your right eye closed, hold the paper about 20 inches away from you.
- Focus on the plus sign with your left eye, and slowly bring the paper closer while still looking at the plus sign.
At some point, the dot will vanish from your sight. This is the blind spot of your retina. If you close your left eye and look at the dot with your right eye, and repeat the process, the plus sign should disappear in the blind spot of your other eye.
A blind spot is normal
Having a blind spot in each eye is a natural occurrence and is typically not cause for concern. It occurs because of the structure of the eye and a lack of photoreceptors. You’re likely not even aware of your blind spot in day-to-day living, because your brain fills in any missing information.
If you’re experiencing a change in vision, floating blind spots, or other vision disturbances, call your eye doctor and schedule an eye exam.