Blind or Blurry Spot In Your Vision

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Blind Spot in Eye: is it Normal?

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 based on 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 Like?

A central scotoma is a blind spot in the center of an individual’s vision. It can appear in various ways. It may appear like a black or gray spot for some people. For others, it may look like 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.

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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).

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 likely 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 like 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 like iPads, Nooks, or Kindle
  • Personal computer hardware like 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.

Resources
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Miller, Paul A et al. “Reducing the size of the human physiological blind spot through training.” Current biology : CB vol. 25,17 (2015): R747-8, https://pubmed.ncbi.nlm.nih.gov/26325131/

Spector RH. Visual Fields. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 116. Available from: https://www.ncbi.nlm.nih.gov/books/NBK220/ 

Saito, Marina et al. “Invisible light inside the natural blind spot alters brightness at a remote location.” Scientific reports vol. 8,1 7540. 15 May. 2018, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5954096/ 

Olivier, P, and G K von Noorden. “The blind spot syndrome: does it exist?.” Journal of pediatric ophthalmology and strabismus vol. 18,5 (1981): 20-2, https://pubmed.ncbi.nlm.nih.gov/7299607/ 

Meyer, J H et al. “Blind spot size depends on the optic disc topography: a study using SLO controlled scotometry and the Heidelberg retina tomograph.” The British journal of ophthalmology vol. 81,5 (1997): 355-9, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1722173/ 

Durgin, F H et al. “On the filling in of the visual blind spot: some rules of thumb.” Perception vol. 24,7 (1995): 827-40, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1722173/

Tripathy, S P et al. “Two-dot alignment across the physiological blind spot.” Vision research vol. 36,11 (1996): 1585-96, https://pubmed.ncbi.nlm.nih.gov/8759461/

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