Why does the dot disappear in a blind spot test?

When you cover one eye and fixate the cross, a moving dot crosses the point where your optic nerve exits. Because that spot has no light receptors, the dot's image falls on it and momentarily vanishes, then reappears on the other side.

Retinal Anatomy

BLIND
SPOT
TEST

Q: What is the eye's blind spot?

The blind spot is a small area of the retina where the optic nerve exits the eye. It has no photoreceptors, so anything whose image lands there isn't seen. Everyone has one in each eye; your brain fills the gap so seamlessly you never notice it in daily life.

Q: Where is the blind spot located?

For each eye, the blind spot sits about 12 to 15 degrees toward your temple (the outer side) from where you're looking, and slightly below the horizontal. It corresponds to the optic disc on the retina, on the nasal side of the eye.

Q: Is having a blind spot normal?

Yes, completely. The physiological blind spot is normal anatomy present in every healthy eye. It is not a defect. If you notice a new blank or missing area in your central vision that doesn't fill in, that is different and worth an eye exam.

Where your optic nerve leaves the eye, the retina has no light sensors — a real hole in your vision your brain quietly paints over. Cover one eye, stare at the cross, and watch a dot vanish as it crosses that hole. We mark where it disappears and reappears to locate and size your blind spot.

Which eye are you testing?

Rightcover left · look at cross

Leftcover right · look at cross

Screen calibration — hold any bank card flat against the screen

MATCH THIS BOX
TO YOUR CARD'S WIDTH

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Not calibrated — assuming a 96 dpi desktop screen

Every card on Earth is 85.6 mm wide. Without this the result is only correct on an unscaled desktop monitor — on a phone it overstates by more than half.

How far are you from the screen? (cm)

A comfortable arm's length is about 50 cm. This sets the angle math — a rough guess is fine.

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Cover your other eye. Stare hard at the cross — never look at the dot. Tap the button the moment the dot vanishes.

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Results

YOUR
BLIND SPOT

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Note

Everyone has this blind spot — it is normal anatomy, not a defect. This tool locates and roughly sizes it for fun and curiosity. The angle figures depend on the viewing distance you entered and your screen's pixel size, so they are approximate, not clinical. Real blind-spot or visual-field testing (perimetry) is done by an eye clinic. If part of your central vision is genuinely missing or blank, see an optometrist.

About the blind spot test

Every healthy eye has a blind spot — a small patch of retina where the optic nerve leaves the eye, containing no light-sensing cells. Anything whose image lands there simply isn't seen, yet you never notice it in daily life because your brain fills the gap from the surrounding pattern and from your other eye. This test lets you find and roughly measure yours: cover one eye, fixate the cross, and a moving dot vanishes as it crosses that gap, then reappears.

Using the viewing distance you enter and your screen's pixel size, we estimate where your blind spot sits (typically about 12–15° toward your temple) and how wide it appears. Those angles are approximate — they scale with your distance — so treat this as a fascinating demonstration of your own anatomy, not a clinical visual-field test. A genuinely new blank area in your central vision is different and worth an eye exam.

Frequently asked questions

What is the eye's blind spot?

The point where the optic nerve exits the retina — it has no photoreceptors, so images landing there aren't seen. Everyone has one per eye.

Why does the dot disappear?

As it crosses the optic-disc gap while you fixate the cross, its image falls on receptor-free retina and briefly vanishes, then returns on the far side.

Where is the blind spot located?

About 12–15° toward your temple from where you look, slightly below the horizontal, in each eye.

Is having a blind spot normal?

Completely — it's normal anatomy in every eye. A new, persistent blank area in central vision is different and should be examined.

BLINDSPOTTEST

Which eye are you testing?

YOURBLIND SPOT

About the blind spot test

Frequently asked questions

BLIND
SPOT
TEST

YOUR
BLIND SPOT