Library · Physiology
The eye's blind spot
Make it clearer
Each eye has a genuine gap: an area where you see nothing. It is not a defect in your eyes, we all have it, and the explanation comes down to wiring.
The optic disc is the point on the retina, the layer at the back of the eye that captures light, where the cables that carry the image to the brain leave the globe: the axons of the ganglion cells. Right there, where those cables exit, there are no photoreceptors, the cells that detect light. With no sensors there is no image, and that is the blind spot.
Its location is known. It falls outward, 10 to 20 degrees from the exact point you are looking at.
There is also a related fact worth keeping in mind: the visual fields of your two eyes are not independent, since they overlap by 120 degrees in the center. In the center, both eyes are looking at the same thing.
The blind spot is also known by its Latin name, punctum caecum, and as Mariotte's spot, after Edme Mariotte, who was the first to realize that this gap in the visual field corresponds exactly to the optic disc.
In brief
The optic disc has no photoreceptors, so each eye has a real blind spot there.
The axons of the ganglion cells leave the eye through that disc, and there are no sensors there.
It falls 10 to 20 degrees outward from the point you are looking at.
The visual fields of the two eyes overlap by 120 degrees in the center.
In the center, both eyes are looking at the same thing.
Mariotte described it first; it is called the punctum caecum or Mariotte's spot.
Sources (3)
- National Center for Biotechnology Information, StatPearls PublishingNeuroanatomy, Cranial Nerve 2 (Optic), StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingNeuroanatomy, Visual Pathway, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingHumphrey Visual Field, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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