The human body consists of many members, each of which plays an important role. One can not sing one another’s place, and one of these members, which is considered one of the most miraculous and complex is the eye, allowing us the eye to enjoy everything that is beautiful through vision.
The eye consists of many parts of the retina, cornea and choroid. The most visible parts of the eye are the iris, which is the pupil, which is the subject of our conversation at its center.
The boy or boy is known to be a blacksmith. This is a hole in the center of the eye. Its function is that it allows the light to pass through it to reach the retina, which converts light rays into nerve signals so that the brain can analyze them.
The secret behind the appearance of the pupil or pupil in black is that the light rays that enter the eye are absorbed either through the tissues inside the eye or absorbed after being reflected and spread within the eye does not come out of the eye due to the narrowness of the pupil.
The pupil in the human is round while this is different in the rest of the animals. We see the pupils in the form of vertical incision in the cats and be horizontal in the goats.
As for its size, it varies according to the intensity of light through the sphincter and extended muscles located in the iris. The sphincter reduces the pupil until it reaches a diameter of 3 to 5 mm in the case of intense light to prevent the large amount of light from entering the eye while the enlarged muscle expand The pupil is in the dim light state to introduce the largest amount of light into the eye where it reaches up to a diameter of approximately 9 mm. The pupil size is also affected by another factor, near or after objects, which is narrowed when you see nearby objects so that the vision is clear and expands at Seeing distant things.
Other things that affect the pupil are also the psychological state, the pupil expands or shrinks in fear as it responds to other situations such as increased attention or pain or other expansion or contraction.
As for the diseases that affect the pupil, it is affected by the disease of cataract (white water), changing color from black to gray as the severity of the disease with severe vision, and some drugs may affect the student, which may cause the contraction of alcohol, including what may cause Its versatility.
It is important to note in the end the need to take precautions while reading and working on the computer and periodic examination of the eye and eye parts in order to maintain safety.