What causes the eye's blind spot?

The optic nerve leaving the eye

How do two eyes help?

Each covers the other's blind spot

How can you find your blind spot?

Close one eye and look at a cross while a dot vanishes

On which side of center is each blind spot?

Toward the outer side of vision

Blind Spot Quiz: Where the Optic Nerve Leaves the Eye

This blind spot quiz closes one eye and hunts for a hole in your vision. Play 10 interactive questions on the optic disc where the nerve exits the eye, why it has no rods or cones, how the brain fills the gap, a simple dot and cross test, Edme Mariotte's 1660 discovery, how two eyes cover each other's gaps and why octopus eyes have no blind spot.

Start Blind Spot Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Cause
What causes the eye's blind spot?
Disc
What is the spot called?
Cells
What does the optic disc lack?
Notice
Why don't we usually notice the blind spot?
Two
How do two eyes help?
Test
How can you find your blind spot?
Who
Who discovered the blind spot in 1660?
Side
On which side of center is each blind spot?
Octopus
Why do octopus eyes have no blind spot?
Fovea
What is the area of sharpest vision called?

Explanations: answer key for all 10 questions

Q1: What causes the eye's blind spot?
Answer: The optic nerve leaving the eye
Everyone has one in each eye.
Q2: What is the spot called?
Answer: The optic disc
It lies off-center on the retina.
Q3: What does the optic disc lack?
Answer: Rods and cones
No light can be detected there.
Q4: Why don't we usually notice the blind spot?
Answer: The brain fills the gap
It guesses from surroundings.
Q5: How do two eyes help?
Answer: Each covers the other's blind spot
The spots fall in different places.
Q6: How can you find your blind spot?
Answer: Close one eye and look at a cross while a dot vanishes
Move the page slowly.
Q7: Who discovered the blind spot in 1660?
Answer: Edme Mariotte
He was a French physicist.
Q8: On which side of center is each blind spot?
Answer: Toward the outer side of vision
It is about 15 degrees off center.
Q9: Why do octopus eyes have no blind spot?
Answer: Their nerves run behind the retina
Evolution wired them differently.
Q10: What is the area of sharpest vision called?
Answer: The fovea
It is packed with cones.

The Hole in Your Vision

Each eye has a blind spot, called the optic disc, where the optic nerve and blood vessels leave the eye. This spot has no rods or cones, so it cannot detect light. It sits about 15 degrees toward the outer side of your field of vision.

We rarely notice it because the brain fills the gap using the surrounding scene, and because each eye covers the other's blind spot. To find yours, draw a cross and a dot, close one eye, stare at the cross and move the page slowly until the dot vanishes. French physicist Edme Mariotte discovered the blind spot in 1660.

Octopus eyes have no blind spot because their nerves run behind the retina instead of in front. The area of sharpest vision, packed with cones, is the fovea, located near the center of the retina.

What This Quiz Teaches

Body science fans will enjoy these questions.

What causes the blind spot
Why we do not notice it
How to find it
Who discovered it
Why octopuses lack one

Did You Know?

Mariotte entertained the French court with it.
Eye doctors examine the optic disc.
Swelling of the disc can signal problems.
Birds have structures near their blind spot.
The test works best with a white page.