You Have a Blind Spot in Each Eye: Here’s How to Find It

We open our eyes and immediately feel as though we are seeing a seamless, complete picture of the world. The wall stretches continuously from one end to the other, the table isn’t missing a section in the middle, and the faces of the people in front of us appear whole.

But physiologically, the image coming from our eyes is not quite as complete as it seems.

In fact, each of your eyes has a “blind spot”—an area in your visual field where the eye cannot detect an image at all. The truly surprising part is that we live with these blind spots every day and almost never notice them.

Why Does the Eye Have a Blind Spot?

At the back of the eye is the retina, a layer of tissue containing light-sensitive cells called photoreceptors. These cells detect light and allow visual information to be transmitted to the brain.

But there is one area of the retina where the optic nerve exits the eye on its way to the brain. This area, known as the optic disc, contains no photoreceptors.

That means that if light from an object falls precisely on this part of the retina, that eye receives no visual information from it. The corresponding missing area in our visual field is known as the “blind spot.”

So why don’t we walk around with a small black hole in our vision?

When both eyes are open, their visual fields overlap considerably. Because the blind spots are in different locations for each eye, information from one eye can often compensate for what the other eye is missing.

But something even more interesting happens when you close one eye.

Instead of simply presenting us with a black patch where information is missing, the visual system uses information from the surrounding area to create the perception of a continuous image.

For example, if your blind spot falls in the middle of a plain white background, you are likely to perceive the missing area as white, too.

Put simply, the brain “fills in the blanks.”

Want to Find Your Blind Spot? Try This

You can demonstrate your blind spot yourself in less than a minute.

Look at these two symbols:

● ✚

Now:

1. Close your left eye.
2. Keep your right eye focused only on the ✚.
3. Do not look directly at the ●.
4. Slowly move your face closer to or farther away from the screen.
5. At a certain distance, the black dot should disappear from view.

It may take a little adjusting to find exactly the right distance. But when the dot disappears, something fascinating is happening: Its image is falling onto the blind spot of the retina in your open eye, where there are no photoreceptors to detect it.

You can test the blind spot in your other eye by reversing the positions of the symbols and closing the opposite eye.

There is an even more interesting version of the experiment.

Draw a horizontal line with a small gap in the middle. If you position the gap so that it falls precisely within your blind spot, your brain may make the line appear continuous, effectively filling in the missing section using the visual information surrounding it.

Your Eyes Detect, but Your Brain Builds the Picture

This simple experiment reveals something much bigger about the way vision works.

We tend to think of our eyes as cameras: Light enters, an image is created, and we simply “see” whatever is in front of us.

In reality, vision is far more complex.

The eyes collect visual information, but the brain processes, combines, and interprets that information to create the visual experience we know.

The blind spot is one of the simplest and most surprising demonstrations of this process. There is genuinely a small area of the visual field where each eye receives no visual information, yet under ordinary circumstances, we perceive the world as complete.

In other words, what we “see” is not simply a perfect copy of everything our eyes detect.

It is the picture our brain constructs from the information it receives.