Why do pupils dilate and shrink with the same light intensity?

Why do pupils dilate and shrink with the same light intensity? Pupil dilation occurs when the pupillary openeris major muscle on the iris is contracted or the pupillary sphincter is suppressed. The round hole in the center of the iris is called the pupil, and the pupil is affected by two muscles on the iris to regulate the amount of light entering the eye, one is the pupillary sphincter, which is innervated by the parasympathetic nerve and is responsible for narrowing the pupil; The other is the pupillary dilator, which is innervated by the sympathetic nerves and is responsible for dilating the pupil.

When the light is strong or the parasympathetic nervous system is excited, the pupil is constricted to prevent too much light from entering the eye and damaging the fundus. When the light is low or the sympathetic nervous system is excited, the pupil dilation and the light entering the eye increases, so that the target can be seen clearly.

Why do pupils dilate and shrink with the same light intensity? Because there are two very small muscles in the iris tissue, one is the pupillary sphincter arranged in a ring around the pupil in the iris, which shrinks the pupil when it contracts. The other is the pupillary dilator muscle, which is arranged radially within the iris, which causes the pupil to dilate when it contracts.

The two muscles are innervated by two nerves, and under normal circumstances, they coordinate with each other and restrain each other, one relaxing, and the pupils are opened or narrowed in a variety of different environments to adjust how much light enters the eye.

: The pupil is a small round hole in the middle of the iris surrounded by the iris. The iris in the eye is disc-shaped, and there is a small round hole in the middle, which is what we call the pupil, also called the pupil.

Pupil dilation and narrowing are mainly caused by the intensity of light, the pupil is like the aperture of a camera, the light is strong when it narrows, and the light is weak when it is enlarged. If you are in a state of strong light for a long time, your pupils will shrink, and when you are in a low light or dark state, your pupils will be dilated!

Pupils only dilate or shrink when the light changes.

Pupil dilation and narrowing are mainly caused by the intensity of light, the pupil is like the aperture of a camera, the light is strong when it narrows, and the light is weak when it is enlarged. If you are in a state of strong light for a long time, your pupils will shrink, and when you are in a low light or dark state, your pupils will be dilated!

The pupil will adjust its size according to the intensity of the external light, and the pupil will become larger when the light is weak, which is the self-protection function of the eye. Secondly, there may be cranial diseases, and there will also be loss of pupil light reflex and corneal reflex. In addition, pupil size can also reflect certain mental activities, and generally when a person is strongly interested or pursuing a certain motivation, the pupil will dilate rapidly.

The pupil mainly controls the amount of light entering the eye and can become larger or smaller. When the light is strong, the pupil will become smaller, and when the light enters the eye, it will not be dazzling; When the light is dark, the pupils are dilated, and the eyes can catch more light and see things better. The pupil is also a response to nervous system function, and in comatose patients, the pupils are often dilated, and when the pupils are completely dilated, it may indicate that the patient has died.

In addition, the pupil is also a manifestation of a person's mental activity, when you see something you like, your pupils will dilate, and when you see something you don't like, your pupils may narrow; When you are afraid, your pupils may dilate, and when you are relaxed and relaxed, your pupils may be narrowed.

In most cases, the pupils change because of the brightness and darkness of the light, and when the light intensity remains the same, the reason why the pupils also dilate and shrink is because of the regulating effect of the brain caused by emotions.

Pupil dilation and contraction is a change caused by the adjustment of the eye muscles, which can make the light enter the inside of the eye to protect the eye.

Why do pupils dilate and shrink with the same light intensity? That's because the normal pupil diameter is 2 to 4, and the pupil is less than 2 mm, which is a miosis, and sometimes it may be more common in iris-cyclitis inflammatory diseases.

The pupil will enlarge and shrink under the condition that the strong light remains unchanged, because the size of the pupil is controlled by the pupil sphincter, and the main role is to adjust the light entering the eye When the light is bright, the pupil is smaller, so that the omentum will not be damaged by the strong light, and the pupil is dilated when it is dark.

The pupil will also dilate when the bright light remains unchanged, and the narrowing is mainly due to a protective mechanism.

This problem is a natural function that the human eye is born with.

Because the size of the pupil is controlled by the pupil sphincter, the main function is to adjust the light entering the eye When the light is bright, the pupil is smaller, so that the omentum will not be damaged by strong light, and the pupil is dilated when it is dark.

Reasons for measuring pupil size under the same care:Because the pupil is a small round hole in the center of the iris in the eye of an animal or human, it is the passage through which light enters the eye. The contraction of the smooth muscle on the iris can reduce or enlarge the diameter of the pupil and control the amount of light entering the pupil.

In the case of different lighting, the pupil will enlarge and shrink according to the light, so the size of the pupil can only be accurately measured by measuring the size of the pupil under the same illumination.

Pupils:

The iris in the eye is disc-shaped, and there is a small round hole in the middle, which is what we call the pupil, also called the pupil. The normal value is that it decreases in bright light and spreads out in low light. The pupil is like the aperture in a camera and can shrink or enlarge depending on the intensity of the light.

We all know when taking pictures that when the light is strong, open the aperture a little smaller, and when the light is dark, open the aperture a little wider, always let enough light enter the camera through the aperture, and make the negative**, but do not let too strong light damage the negative. The pupil also has a function like Luyun, but its adaptation to the intensity of light is automatic. Through the adjustment of the pupil, the right amount of light enters the eye at all times, so that the image of the object falling on the retina is clear, and there is no excessive light burning the retina.

How to measure pupil size:1.The diameter of the pupil in the bright area is easy to measure, and it can be measured directly.

2.In the dark, you can use the following methods: adapt to more than half an hour in the dark, light a light-emitting diode a few meters away (use a charger or an electrical indicator light), use some cardboard cut into strips of different widths to cover your pupils, if you can cover yourself so that you can't see the luminous point, the width is greater than the diameter of the pupil, and vice versa, you can know the size of your pupil by comparing it many times.

The light-emitting diode should be red eggplant, and the brightness should not be too high.

Both the visual pathway and the visual afferent pathway, which part of these two aspects are affected, may cause pupil dilation, as follows:

1. The pupil is innervated by the pupillary sphincter and the pupil dilation muscle, which may cause paralysis of the pupil sphincter when subjected to trauma, which will cause pupil dilation, or iris avulsion, or may cause irregular pupil dilation, resulting in cycloplegia.

2. For example, using some paralytic drugs for the ciliary muscle, often doing dilated refraction, and dropping compound tropicamide or atropine eye drops can also cause pupil dilation, and with the decrease of drug effect, the pupil will gradually return.

3. Lesions of the central nervous system, such as cerebral hemorrhage and cerebral congestion, can also be accompanied by narrowing or dilation of the pupil.