Is a Blind Spot in the Eye Normal?
If you've ever switched lanes thinking it's clear before realizing a car is driving next to you, then that's an example of a blind spot. It's also typically called a scotoma.
A scotoma is where the optic nerve and blood vessels leave the eyeball. Everyone has a blind spot here that’s about the size of a pinhead. This blind spot is normal and usually not a cause for concern.
Blind or dark spots that appear suddenly or grow larger may be symptoms of an eye disease that needs treatment, such as:
What Can Cause a Blind Spot in Your Eye?
Not all blind spots are normal. A noticeable blind spot that interferes with everyday activities like reading or driving may be a scotoma.
Typically the optic nerve passes electrical signals into your brain to create a visual image. A scotoma may be a spot on the retina where your nerves don't work or send signals to your brain.
Causes of a Temporary Blind Spot
Some scotomas are temporary. Causes of a temporary scotoma include:
- Hormonal changes
- Oncoming migraines
- Low blood flow to the brain
Causes of a Permanent Blind Spot
A scotoma that’s fixed or doesn’t go away may be due to:
- Stroke or transient ischemic attack (TIA)
- Brain tumor
- Head injury
- High blood pressure (hypertension)
- Multiple sclerosis (MS)
- Optic nerve damage or inflammation
- Diabetic retinopathy
- Macular degeneration
A blind spot that grows larger over time can be a symptom of retinal detachment. In this case, surgery may be necessary.
When Should You Worry About a Blind Spot?
Call your eye doctor and schedule an exam if you notice any of the following:
- Change in vision
- Your blind spot is getting larger
- Floating blind spots
- Flashing lights that occur with the blind spot
- Needing bright light to see well
- Other vision disturbances
Why Does Everyone Have a Blind Spot?
Each of your eyes has a small functional blind spot where the optic nerve moves through the retina. This spot is called the optic disc, and it’s 1.5 millimeters in diameter.
No cells respond to light (photoreceptors) in this tiny area. The lack of light-sensitive cells causes a blind spot.
Without light-detecting cells, your eye can’t transfer messages about an image to your brain, and your brain can’t interpret the image for you. As there are no cones or rods at this point on the retina, you have a small gap in your visual field.
What Do Blind Spots in Vision Look Like?
A central scotoma is a blind spot in the center of your vision. It can appear in various ways, including:
- A black or gray spot
- A blurred smudge
- Distortion in your central vision
Most of the time, you don’t 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 minor nuisance and then become larger, or there may be several scotomas that block your field of vision.
Scotomas in the periphery of a person’s vision are not as concerning or disabling as those in the center.
Why Don’t We Notice Blind Spots?
There are ways to force yourself to notice the blind spot. However, people typically overlook the blind spot in their day-to-day lives.
Some research suggests that the opposite eye compensates for the missing imagery information.6 This proposes that the visual fields overlap when both eyes are open 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. The blind spot is almost impossible to notice even if you shut one eye. This is because your brain is so skilled at providing the missing information that you never see the blind spot.
How to Find the Blind Spot in Your Eye
Your blind spot is easy to find. Here are two simple tests you can do at home to find the blind spot in both eyes.
Finding Your Blind Spot with a Pen and Paper
If you have a piece of paper that’s wider than six to eight inches and a pen or marker, you can try this test:
- Make a small dot on one side of the paper
- Draw a small plus (+) sign six to eight inches to the right of the dot
- Close your right eye and hold the paper about 20 inches in front of your face
- Focus on the plus sign while moving the paper closer to you
- When the dot disappears, you've found the blind spot in your left eye
You can alter this process to find the blind spot in your right eye. Simply close your left eye and focus on the dot. Move the paper until the plus sign disappears.
Using Your Hands to Find Your Blind Spot
You don’t need any materials for this test. You can use your own hands to find the blind spot in your right eye:
- Close your left eye and keep it closed
- Stick out your left thumb and hold it at arm’s length in front of your face
- Using your right eye, focus on your left thumb
- Hold out your right thumb next to the left
- Keeping your eye on your left thumb, slowly move the right thumb to the right
- Your right thumb will seem to disappear when it reaches your blind spot
To find the blind spot in your left eye, close your right eye and stare at your right thumb while moving the left.
Blind Spot Treatment
Scotomas can be treated to improve vision. However, your treatment depends on the cause of the scotoma.
If the scotoma is on the outer edges of your vision, it usually won't cause severe vision issues. Blind spots that don’t affect your vision may not need treatment.
Permanent scotomas don’t go away with typical vision correction treatments like glasses and contact lenses. Treating the underlying cause can help prevent new scotomas from forming. For example, if a blind spot is due to hypertension, treatment may focus on managing your blood pressure.
Assistive Technology for Blind Spots
Your healthcare provider may suggest using assistive devices and technologies 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.
Eye Exercises to Shrink a Blind Spot
Research suggests you can shrink your blind spot using certain eye training exercises. One small study found that specific eye exercises could shrink the blind spot by as much as ten percent.1
This research proposes that this improvement would be so minor people wouldn’t even notice it. This is partly because most people don’t see their blind spots.
Everyone has a blind spot in their eye where the optic nerve connects to the retina, this is often referred to as a scotoma. Although it's always there, most people don't notice their normal blind spot.
If you're curious about your blind spot, there are at-home tests you can try to find it. However, not all blind spots are normal.
Some scotomas may be a symptom of a serious eye condition like glaucoma or macular degeneration. Contact an eye doctor if you notice a blind spot or other visual disturbances that interfere with normal activities.
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