Look at your eyes in the mirror, do you see a black circle in the middle of the eye? It is the pupil of the eye. What is the pupil of the eye and how does it work? Let's explore the answer in the following article.
The eye is one of the sense organs that is used the most among the five senses. Almost all information and stimuli received by humans come from the sense of sight through the eyes. All parts of the eye have their respective functions, including the pupil of the eye.
How the pupil of the eye works
The pupils of a normal eye are perfectly round and black in color. In adults, the pupil is usually between 2-4 millimeters in bright light, and 4-8 millimeters in dark.
The way the pupil works is the same as aperture camera, which is to determine how much light enters and is captured by the eye.
This dilation or contraction of the pupil occurs automatically thanks to the nerves in the eye. In low light conditions or in darkness, the pupil will dilate, so that more light reaches the retina to support vision.
Conversely, in bright conditions, the pupil will shrink to limit the light that enters the eye. If too much light enters the eye, the eye can be blinded and the vision becomes uncomfortable, it can even damage the lens and retina of the eye.
Pupils will also change size when looking at objects at a certain distance. When the object seen is very close to the eye, for example while reading a book, the pupil will shrink. The pupil reduction of the eye when viewing close objects is intended to prevent blurred vision and improve focus or quality of vision.
In addition to lighting and looking at objects, the pupil can change size in reaction to other stimuli. For example, the pupil may become larger when you are excited or anxious. Diseases or side effects of certain medications can also cause the pupils to dilate or shrink.
Eye Pupil Anatomy
The pupil and iris (the part that gives color to the eye) work together to control the amount of light entering the eye, so that it can be focused on the retina to initiate the process of vision. The pupillary action is controlled by the sphincter and eye dilator muscles in the iris.
The sphincter muscle is a ring-shaped muscle that wraps around the rim of the pupil. When in a bright place, the sphincter muscles will contract to reduce the size of the pupil. While the dilator muscle, which is the muscle in the iris, will widen the size of the pupil when it is in a dark place. This muscle works on orders from the optic nerve.
Under normal conditions, the pupil size of the left and right eyes will be the same and are perfectly round in shape. However, if the size of the pupils of the two eyes looks very different, the pupils of the eyes do not look round, or if the pupils of the eyes widen or shrink and cannot return to their normal size, then there is a high probability that there is an abnormality in the pupil of the eye.
The pupil of the eye plays an important role in vision. Disorders of the pupil or other parts of the eye will cause visual disturbances. If you experience complaints in the eyes or vision, immediately consult an eye doctor, so that the cause can be identified and given treatment before it gets worse or complications occur.