Find your Blind Spot


Did you know that each of your eyes is completely blind in one spot?  This so-called blind spot is actually quite large, and it creates a hole near the center of our visual world.  Try the following quick experiments to find your blind spot and see its effects.

Things To Try

Blindspot 01 Blindspot 02 Blindspot 03 Blindspot 04 Blindspot 05 Blindspot 06

How It Works

Anatomy of the human eye
Structure of the human eye. [1]

The figure above shows the structure of a human eye and the retina inside it.  The retina, which is similar to a camera's image sensor, is made up of millions of photoreceptors (pixels) called rods and cones.  The visual information recorded by these photoreceptors are collected by the optic nerve [2].  Since there are no photoreceptors at the head of the optic nerve, it forms a spot of no visual input.  Any image formed at this spot is not sensed.  While the size of this spot varies from individual to individual, it is actually rather huge - about 4° to 6°.  That means that if you close one eye, there is a hole in your visual world that is an inch or two across at arms length!

As you saw for yourself, the brain automatically "fills in" the blind spot with a simple extrapolation (extension) of the image surrounding the blind spot.  The white disc in the pictures above was filled in with the surrounding black background.  The sun was seamlessly replaced by the sky.  This is why you do not notice the blind spot in your day-to-day observations of the world, but as you might have noticed from examples above, the brain only fills it in with plausible "patterns" and not plausible "information."

Bigshot Connections

Fun Facts

Octopus Eyes

The octopus is a rare example of an animal that does not have a blind spot.  In an octopus eye, the optic nerve extends from the back of the retina instead of the front, leaving no part of the retina blocked [3].



[1] "Anatomy of human eye and retina," [Online image]. Available: http://webvision.umh.es/webvision/sretina.html. [Accessed: Oct 4, 2012].
[2] E. N. Marieb and K. Hoehn, Human Anatomy & Physiology. Benjamin Cummings, 2006
[3] M. F. Land and D. E. Nilsson, Animal Eyes. Oxford university Press, 2002