Everyone has a small blind spot in each eye where the optic nerve meets the retina. That spot is the optic disc, and it is normal.1 A blind spot that appears suddenly, grows larger, or affects one eye differently from the other is a different story. It is called a scotoma, and it can signal retinal detachment, glaucoma, optic nerve damage, or a neurological event.6 Here is what causes a blind spot in one eye and when you should see a doctor.
Is a Blind Spot in the Eye Normal?
Yes, a small blind spot in each eye is normal. It sits where the optic nerve passes through the retina, and your brain fills it in so smoothly that you almost never notice it.
This is different from the "blind spot" drivers describe around a car. That kind of blind spot comes from mirror position and car design, not your eye. Your eye's normal blind spot is a small gap in the visual field that you only notice when one eye is closed and an object lands right on it.
What is not normal is a blind or dark spot that arrives suddenly, expands, or stays put when you blink. Those changes can point to a treatable or urgent eye condition, including:
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Blind Spot vs. Scotoma: What Is the Difference?
Doctors use the word scotoma to describe any area of reduced or missing vision.6 The normal optic-disc blind spot fits that definition too. Clinicians call it a physiologic scotoma because it is built into the anatomy of every healthy eye.
A new, larger, or symptomatic scotoma is different. It is called pathologic, and it points to a problem in the retina, optic nerve, or visual pathways in the brain. That kind of scotoma is a clinical finding that needs an eye exam.
In short: the normal blind spot is a physiologic scotoma. A new or changing scotoma is a symptom.
Why Does Everyone Have a Blind Spot?
Each eye has a spot called the optic disc, where the optic nerve leaves the retina to send signals to the brain. The optic disc is a small oval area, roughly 2 by 1.5 millimeters across.2
This patch contains no photoreceptors (no rods or cones), so no light is detected there. Because the retina cannot register an image at the optic disc, your visual field has a small gap at that spot in each eye.
You do not see the gap in daily life for two reasons. First, the other eye covers the same patch of visual space, so binocular vision fills in the missing data. Second, the brain reconstructs the area using surrounding visual cues, a process researchers call perceptual filling-in.3
What Causes a Blind Spot in One Eye?
Not all blind spots are normal. A noticeable blind spot in one eye that disrupts reading, driving, or peripheral awareness is usually a scotoma, and the cause matters.
A scotoma happens when signals from part of your visual field do not reach the brain. The breakdown is in the retina, the optic nerve, or the visual pathways in the brain itself.1
Causes of a Temporary Blind Spot
Some scotomas come and go. Common causes include:
- Migraine aura, including ocular migraine
- Stress or sudden hormonal shifts
- Temporary reduced blood flow to the retina, optic nerve, or visual pathways
- Transient ischemic attack (TIA) or amaurosis fugax, brief vision loss caused by a short interruption in blood flow
- Medication side effects
Temporary scotomas usually resolve within minutes to hours. Any sudden vision loss in one eye still needs same-day medical evaluation, because brief vision loss can be a warning sign of a stroke or other vascular trouble.
Causes of a Permanent Blind Spot
A scotoma that stays put is usually tied to a structural problem in the eye or brain:6
- Retinal detachment
- Glaucoma, which damages the optic nerve and causes peripheral vision loss7
- Diabetic retinopathy
- Macular degeneration
- Optic nerve damage or inflammation (optic neuritis), sometimes linked to multiple sclerosis
- Stroke or other brain injury affecting the visual pathway
- Brain tumor or head injury
- Untreated high blood pressure
Permanent scotomas usually do not improve on their own. Treatment focuses on the underlying condition, and outcomes depend on how quickly the cause is found and managed.
When Should You See a Doctor?
Sudden loss of vision in one eye, a dark curtain or shadow across your visual field, a burst of new floaters or flashes, or a new blind spot with severe headache are medical emergencies. Get care right away.8
New flashes or a sudden increase in floaters need urgent attention even when they come and go, especially if they appear with a curtain, shadow, or any drop in vision. These can be signs of retinal detachment, stroke, or rapidly rising pressure inside the skull. Retinal detachment in particular needs urgent treatment to prevent permanent vision loss.
Schedule a non-emergency eye exam if you notice:
- A blind spot that is new, growing, or shifting position
- A blind spot in one eye that does not match the other
- Ongoing floaters or flashes that have already been evaluated and are not worsening
- Trouble seeing in low light or needing more light to read
- Other unexplained vision changes
Peripheral blind spots tend to be less disabling than central ones, but they still need evaluation. They can be the first sign of glaucoma or a slowly progressing retinal problem.7
What Do Blind Spots in Vision Look Like?
A central scotoma sits in the middle of your vision. It usually appears as one of three things:
- A black or gray patch
- A blurred or smudged area
- Distortion that warps straight lines or faces
Most people do not see whatever sits directly inside a scotoma until they shift their eyes or turn their head. Some scotomas start small and grow over time, and some people develop several scotomas scattered across the visual field.10
Peripheral scotomas, which sit at the edges of vision, are usually less disruptive than central ones. They still need evaluation if they are new, spreading, or come with flashes, floaters, or a curtain or shadow across vision.
Why Do We Not Notice Our Blind Spots?
Most people never notice their normal blind spot, even with one eye closed.
The opposite eye covers the same patch of visual space, so binocular vision fills the gap when both eyes are open. The brain also uses surrounding patterns, colors, and edges to predict what likely sits in the missing region. This perceptual filling-in is so consistent that most people experience a continuous visual world despite the missing retinal input.3
How to Find the Blind Spot in Your Eye
You can find your blind spot at home with two simple tests. They are reassurance exercises, not diagnostic tools. They will not detect a scotoma.
Finding Your Blind Spot With a Pen and Paper
If you have a piece of paper wider than six to eight inches and a pen, try this:
- 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 have found the blind spot in your left eye.
To find the blind spot in your right eye, 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 can do this test with no materials at all. To find the blind spot in your right eye:
- Close your left eye and keep it closed.
- Stick out your left thumb at arm's length in front of your face.
- With your right eye, focus on your left thumb.
- Hold out your right thumb next to the left one.
- Keeping your eye on the 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, focus on your right thumb, and move the left.
Blind Spot Treatment
Treatment depends on what is causing the scotoma. Some scotomas improve once the underlying condition is treated, and some are permanent.6
Standard vision correction such as glasses and contact lenses does not erase a scotoma. If the cause is high blood pressure, treatment focuses on managing blood pressure. If the cause is glaucoma, treatment lowers eye pressure to keep the optic nerve from losing more function, although it cannot undo damage that has already happened.7 Retinal detachment usually needs laser, freezing, or surgical repair.8
Scotomas at the outer edges of vision may be less noticeable than central ones, but treatment still depends on the cause. Some cases are watched over time, while glaucoma, retinal disease, and neurological causes need active treatment to prevent further vision loss. Central scotomas typically need a more involved plan.
Assistive Technology for Blind Spots
If a scotoma affects daily tasks, vision rehabilitation helps you make the most of the vision you still have.9
Common options include:
- Magnifying glasses or hand-held and stand magnifiers for reading
- Magnification and screen-reader software on phones, tablets, and computers
- Large-print books and adjustable text size on e-readers
- Specialized lighting and reading stands to reduce glare and fatigue
- Prism lenses to shift images out of a blind spot into a clearer area of vision5
- Referrals to low-vision specialists for daily living support
Talk with your eye doctor about which tools fit your scotoma and your daily routine.
Eye Exercises and the Normal Blind Spot
One small study found that targeted eye-training exercises shrank the normal physiological blind spot by roughly ten percent.4,5 The improvement was too small for participants to notice in daily vision, and the researchers framed it as a perceptual finding rather than a treatment.
These exercises do not treat a scotoma caused by retinal, optic nerve, or brain disease. If you have a new or growing blind spot, the right next step is an eye exam, not at-home training.
Summary
A small blind spot in each eye is normal. It sits at the optic disc, where the optic nerve leaves the retina, and the brain fills it in so well that most people never notice it.1
A blind spot in one eye that appears suddenly, grows, or differs between eyes is a scotoma, not the normal blind spot. Possible causes include retinal detachment, glaucoma, optic nerve damage, stroke, and other neurological conditions.
Sudden vision loss, a curtain across vision, or a burst of new floaters and flashes are medical emergencies.8 For any new or changing blind spot that is not an emergency, contact an eye doctor for an exam.
