Blind spot is a tiny area at the back of each eye. Blind spot is the region where the optic nerve passes through the optic disk and out of the eyes. Also, it is at this very region that the blood vessels enter the eyes. It lacks photoreceptor cells (rods and cones) in the retina so the light falling at this spot does not form any image. Edme Mariotte observed it for the first time in 1660.
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All the vertebrates have a blind spot. Octopus and other cephalopods do not contain a blind spot as the nerve fibres do not disrupt the retina and pass from behind the retina.
The blind spot of the right and left eye is present at the right and left side of the central vision, respectively. As the visual area of both the eyes overlap, we do not perceive blind spots with both eyes open.
What is scotoma?
It is an area of partial alteration in the visual field that has degenerated or partially diminished visual acuity. This area is usually surrounded by a field of normal vision. The scotoma in the mammalian eye is usually termed as its blind spot.
Blind spot in humans – Every human has the blind spot. It is located at 12-15° temporally where the optic nerve leaves and 1.5° below the horizontal meridian and is roughly 5.5° wide and 7.5° high.
Fovea
Earlier it was believed that the area where the optic nerve enters should be the most sensitive area but the most sensitive area to light is present laterally to the blind spot. It is known as fovea or fovea centralis. It is a tiny depression present in the yellowish spot called macula lutea. The fovea is the area where the retina is thin and it allows the light to fall directly on the densely packed cones. It is the region of the clearest vision.
So the blind spot is the area where there is no visual perception and the fovea is the region of the greatest resolution.
This was in brief about the blind spot. Test your understanding with MCQs on Structure of Eye, only at BYJU’S.
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