Reasons Why You May Have a Blind Spot in Your Eye

Blind Spot in Your Eye? Possible Causes and What to Do

Reasons Why You May Have a Blind Spot in Your Eye

If you have ever been driving, ready to switch lanes believing it is clear, and you turn your head to double-check and realize there is a car driving next to you, this is one example of a blind spot. The blind spot is also called the scotoma.

The blind spot is completely normal and is usually not something of concern.

Why Is There A Blind Spot in the Eye? 

The scotoma is where the optic nerve and blood vessels leave the eyeball. The optic nerve connects to the brain. It takes images to the brain, where they are processed.

This is how you know what you are seeing. Your eyes view the object or image, and then your brain interprets it. Brains usually fill in any information we require the images surrounding our blind spot, so we do not usually notice it.

Side-view mirrors on cars are a great example of how people compensate for blind spots. Often, cars traveling next to you fall into your blind spot. The side-view mirrors provide you with a different angle to look at the same area.

The side-view mirrors enable you to ‘see’ in your blind spot. A recent study showed that specific eye exercises could help shrink the size of the blind spot.1 However, more research is necessary.

If one eye is trained, these benefits do not transfer to the other untrained eye.

What Do Blind Spots in Vision Look ?

A central scotoma is a blind spot in the center of an individual’s vision. It can appear in various ways. It may appear a black or gray spot for some people. For others, it may look a blurred smudge or a distorted view in their straight-ahead vision. Or, in many cases, you simply do not see an object directly in front of you until you move your eyes or head away from the blind spot.

Blind spots may begin as a small nuisance and then become larger. Or, there may be several blind spots or scotomas that block your field of vision.

Scotomas that occur in the periphery of a person’s vision are not as concerning or disabling as those developing in the center.

What Can Cause a Blind Spot in Your Eye?

Each of your eyes has a small functional blind spot approximately the size of a pinhead. In this small area, where the optic nerve moves through the retina's surface, there are no photoreceptors (cells in the retina that respond to light). Additionally, some eye diseases might cause blind spots to form.

As there are no light sensitive cells, it produces a blind spot. Without light detecting cells, the human eye cannot transfer any messages about the image to the brain, which typically interprets the image for you.

The optic disk is around 1.5 millimeters or 0.06 inches in diameter. It is the point where the optic nerve exits the human eye. It is also where the major blood vessels enter to deliver blood flow to the eye.

As there are no cones or rods at this point on the retina, there is a very small gap in the visual field. You have a small gap in your vision where you are essentially blind.

When Should You Worry About a Blind Spot?

Having a blind spot in both the right and left eye is natural. It is not typically a cause for concern. You are ly not even aware of your blind spot in day-to-day living as your brain fills in any missing information.

However, if you notice the following, you should speak with your eye doctor and schedule an eye exam:

  • Change in vision
  • Your blind spot is getting larger
  • Floating blind spots
  • Other vision disturbances

How to Test for a Blind Spot in Eye

You may decide you would to find your blind spot. In your left eye, your blind spot is approximately 15 degrees to the left of your central vision. This is equal to two hand widths if sticking out your arm.

In your right eye, your blind spot is about 15 degrees to the right of your central vision.

To discover the blind spot in your eye, there is a simple test you can perform. On a piece of paper, mark a small dot. Approximately six to eight inches to the right of the dot, create a small plus sign.

With your right eye closed, place the paper approximately 20 inches away from you. Focus on the small plus sign with your left eye and bring the paper closer while still looking at the plus sign.

At some point, the dot will disappear from your sight. This is the blind spot or scotoma of your retina.

If you close your left eye and stare at the dot with your right eye, and repeat the test, the plus sign should vanish in the blind spot of your other eye.

Why Don’t We Notice the Blind Spot?

There are ways to force yourself to notice the blind spot. However, people typically overlook the scotoma in their day-to-day lives.

Some research suggests that the opposite eye compensates for the missing imagery information.7 This proposes that when both eyes are open, the visual fields overlap and fill in the missing data for the opposite eye.

Another theory is that the brain fills in the missing information using visual cues in the environment. Even if you shut one eye, the blind spot is almost impossible to notice. This is because your brain is so skilled at providing the missing information that you never see the blind spot.

Can Blind Spots be Treated? 

Yes, blind spots can be treated to improve vision. Treatment depends on the cause.

A scotoma that occurs before a migraine headache is temporary and usually fades within an hour. If the blind spot is on the outer edges of your vision, it does not typically cause severe vision issues. 

If you have a scotoma in your central vision, it may not be able to be treated with glasses, contact lenses, or surgery. 

Your healthcare provider will suggest that you use aids to support your decreased vision. 

 Tools that can help include:

  •  Large-number phone keypads and watch faces
  • Filters to lessen the glare on computer screens
  • ‘Talking’ clocks or scales
  • Audiobooks, magazines, newspapers, or machines that ‘read’ printed material aloud
  • Large type printed books
  • Enlarging the type size in an eReader on electronic devices iPads, Nooks, or Kindle
  • Personal computer hardware lighted keyboards and software that magnifies screens and transforms text to speech for computers and mobile phones
  • Closed CCTV systems that use video cameras
  • Large TV screens to enlarge reading material
  • Magnifying eyeglasses, hand-held magnifiers, or stand magnifiers to enlarge reading material or other objects
  • Prism lenses to move images from blind spots into areas with normal vision

Speak with your eye doctor or healthcare provider for professional medical advice on treating the blind spot.

Can You Shrink a Blind Spot?

Researchers have discovered that you may be able to shrink your blind spot by using certain eye training exercises. In a small study consisting of ten participants, researchers learned that specific eye exercises could shrink the blind spot by as much as ten percent.1

The exercises used in the study involved setting an image of a small ring directly in an individual’s blind spot and showing waves of light and dark bands moving through the ring. The participants were requested to determine which way the bands were moving through the ring and the ring's color.

The size of the ring was changed so that it was detectable about 70 percent of the time at the start of the study. Then the researchers adjusted the size so that it was so small it was entirely hidden by the blind spot.

In time, the participants were better able to detect the small image in their blind spot and judge the color of the ring and the direction of the moving bands. This research proposes that this improvement would be so minor that people would not even notice it. This is partly because most people do not even see their blind spot anyway.


What is the blind spot in my eye?

Reasons Why You May Have a Blind Spot in Your Eye
HomeConditions | Blind spot

Every human eye has something called a blind spot. This natural blind spot is the place in the retina — the light-sensitive inner lining at the back of your eye — that doesn’t have any cells that respond to light. The blind spot sits in the part of your retina where the optic nerve exits the eye.

Why do you have blind spots?

Blind spots are a normal part of your vision. Why? The optic nerve, which communicates with your brain, passes through a hole in the retina. Because of that hole, we can’t see images that hit that spot.

The place in the eye where the optic nerve exits is called the optic disc. The optic disc can’t sense light because there’s not enough room in that tight spot, which is stuffed with nerves, for cells known as photoreceptors.

Photoreceptors are special cells in the eye that transform light into signals that head to the brain. There are two types of photoreceptor: cones and rods. These cells supply our color vision and night vision.

Why don’t we usually notice our blind spots?

Your brain makes up for the gap in vision caused by our blind spots. How? The brain fills the void by blending the images from both our eyes. Therefore, you normally don’t realize that you have a blind spot in your right or left eye.

How can you find your blind spots?

Anyone can find the blind spot in each eye. Here are a couple of different ways.

One simple test involves a blank piece of unlined paper and a marker:

  1. On the piece of paper, draw an O on the left side and an X on the right side.

  2. Put your right hand over your right eye.

  3. Hold the piece of paper in your left hand at arm’s length.

  4. Focus your left eye on the X.

  5. Keep focusing on the X, and move the paper toward your face.

  6. When you can’t see the O, you’ve found the blind spot in your left eye.

To find the blind spot in your left eye, repeat the steps above with the opposite eye.

Here’s another way to find the blind spots in your eyes:

  1. Close your left eye.

  2. Hold your left thumb at arm’s length. 

  3. Look at your left thumb with your right eye. 

  4. Hold your right thumb next to your left thumb.

  5. Keep looking only at your left thumb while slowly shifting your right thumb to the right. Your right thumb will vanish when your thumbs are about 6 inches apart. That’s the blind spot in your right eye.

  6. After you discover the blind spot in your right eye, move your right thumb around to tell how big the blind spot is.

To find the blind spot in your left eye, repeat the steps above with the opposite eye.

Can your blind spots be fixed?

While you can’t get rid of your blind spots, you may be able to “shrink” them. A study published in 2015 found that people who trained their eyes using a computer monitor and an eye patch were able to reduce the size of a blind spot by 10%. However, training one eye did not improve the blind spot of the untrained eye.

Are there any blind spots that are potentially dangerous?

We all have natural blind spots in our eyes that we usually don’t notice. But some people have blind spots that may indicate a serious eye condition. Sudden blind, blank or dark spots in our vision might be a symptom of:

  • Diabetic retinopathy – Caused by diabetes. Diabetic retinopathy damages the retina and can lead to blindness.

  • Macular degeneration – Gradually blurs your vision over time.

  • AIDS-related eye problems – The most common eye problem among people with AIDS is cotton wool spots, which are white spots on the retina that do not cause vision loss.

Do all animals have natural blind spots?

Most vertebrates do. However, while the structure of their eyes are similar to those of humans, squids and octopuses don’t have blind spots.

How is that possible? Because they have photoreceptor cells that are oriented toward the light, not away from it. Therefore, their photoreceptor nerves run behind the retina, meaning there are no blind spots.

In human eyes, the photoreceptor cells are oriented away from the light, not toward it, and the photoreceptor nerves are in front of the retina.

When should you see a doctor about a blind spot?

If you suddenly notice a blind spot that hasn’t been there before, you have a blind spot that interferes with your normal vision or you have other changes in your vision, you should make an appointment to see your eye doctor immediately. Your doctor will do a comprehensive eye exam to determine if there’s any cause for concern and to check your overall vision health.  

READ NEXT: Scotoma: Blind spot in vision

Page published in May 2021

Page updated in October 2021


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