What Is The Function Of Pupil
Pupil Eye Meaning
The pupil is the black hole located at the center of the iris of the eye which allows light to reach the retina.
The pupil is an opening in the iris of the eye, through which light enters before it reaches the lens and is focused on the retina. The muscles of the iris regulate the size of the opening; they quickly constrict the pupil when it is exposed to bright light, and dilate the pupil when in dim light.
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Pupil is an open source eye tracking platform that enables researchers and developers to study and develop assistive technologies that serve human needs.
Eye Pupil Meaning
The pupil is the small black circle in the centre of the iris. It is a tiny hole present over the lens through which light enters the eye and focuses on the retina for image formation. The iris muscles regulate the size of the pupil and control the amount of light entering it.
The pupil, located in the central opening of the iris, is typically black in colour. The surrounding area of brown, blue or grey is called the iris, while the outer white area is the sclera.
The pupil typically appears round in shape and black in colour, and is generally equal in size. The black colour is a consequence of light passing through the pupil and being absorbed by the retina, instead of being reflected back.
Also Explore:
| What is the function of the iris? |
| What is the sclera of the eye? |
Pupil: Function
The pupil is black because all the light that goes into the eye is absorbed by the retina. It is similar to the aperture of a camera. There are two types of iris muscles that control the size of the pupil:
Circular Sphincter Pupillae - Constricts Pupil on Contraction
Radial Dilator Pupillae - Dilates Pupil upon Contraction
The pupillary light reflex is a process that controls the diameter of the pupil and adjusts the light intensity entering the eye. This is done by responding to the light striking the ganglion cells in the retina at the back of the eye. In dim light, the pupil will dilate, and in bright light, it will constrict. This helps to protect the lens and retina from damage due to high light intensity, and also allows people to see clearly in dim light.
The color of the pupil becomes pale yellow when the lens becomes opaque or cloudy in case of cataract.
What is the size of the Pupil?
From person to person, the size of the pupil differs. In some it is small and in some it is large; it also varies with age wherein young adults tend to have a bigger pupil.
Typically, the normal size of the pupil’s diameter in adults ranges between 2 and 4 millimetres in bright light, and in the dark it ranges from 4 to 8 millimetres.
Pupils usually constrict while being affected by light when focused on an object nearby; this is referred to as the accommodative pupillary response.
Dilated Pupil
The muscles of the iris govern the size of the opening. They instantly constrict upon exposure to bright light and dilate the pupil when in dim light. The parasympathetic nerve fibres arising from the third cranial nerve innervate the muscles which induce the constriction of the pupil. On the other hand, the sympathetic nerve fibres regulate the dilation. The pupillary aperture in addition, channels while focusing on objects nearby and dilates when viewing objects at a distance.
The pupil changes its size to allow more or less light to enter the eye. These movements are not voluntary, but rather involuntary, and are regulated by the autonomic nervous system. When there is low light, the pupil dilates, increasing in size and allowing more light to pass through. This is done by the dilator pupillae muscle, which is controlled by the sympathetic nervous system.
Frequently Asked Questions
Pupil is the black, circular opening in the center of the iris of the eye that allows light to enter the retina.
The shape of the pupil is usually circular in most eyes.
The pupil in humans is a small black circle in the centre of the iris. It is usually round, but the shape can differ between species; reptiles, foxes, and cats often have vertical slit pupils.
How does pupil size get determined?
The circular sphincter pupillae constricts the pupil upon contraction, while the radial dilator pupillae dilates the pupil upon contraction. These two muscles are responsible for controlling the size of the pupil.
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