Question

At the junction of the optic nerve and the retina, there are no sensory cells, so no vision is possible at that spot. This is called the blind spot.
A) True
B) False

Answer 1

Retina is a thin layer of neural tissues at the back of eye. It is made up of photoreceptors. Photoreceptors are tiny, light-sensitive cells. It is an area on the retina without the receptors that can respond to light. If an image falls on this area then it can not be seen. In this region, the optic nerve exits the eye and enters the brain.

Complete step by step answer:
When light enters the retina, it sends electrical signals from the optic nerve to the brain. The brain then turns the signal into a picture.
At the junction where the optic nerve enters the eye, there are no rod or cone cells to sense the image. Therefore, no vision is possible at that spot. The retina fails to send any signals to the brain. Hence no image is formed.
Hence blind spot is the point of entry of the optic nerve insensitive to light. It is also known as a scotoma.

Given statement is true. Option A is the right answer.

Note:
It is to be noted that both eyes of human beings have natural blind spots. But blind spots can also be artificial in some cases. For example when a bright flash of light is made to fall on the eye, then the retina is not able to sense the object and hence not able to send signals to the brain. As a result, no image is formed on the retina. This is known as local blindness that lasts for a few seconds only.