What causes pupil dilation? These are the most common reasons

There are physiological and pathological reasons for pupil dilation. Normally, when we see something we particularly like, our pupils will dilate unconsciously. Also, the pupils adjust their size according to the intensity of light, which can protect our eyes very well.

1. The pupil not only responds to light and darkness and adjusts the light entering the eye, but also affects the depth of focus and spherical aberration of the eye's optical system. The range of pupil changes can be very large. When extremely contracted, the diameter of the human pupil can be less than 1mm, and when extremely dilated, it can be greater than 9mm. The iris sphincter can shrink to 87% of its length, which is almost impossible for other smooth muscles or striated muscles in the human body to achieve. The pupil will adjust its size according to the intensity of external light. When the light is strong, the pupil becomes smaller, and when the light is weak, the pupil becomes larger. This is a self-protection for the eyes.

2. Many times, some people’s pupils are dilated without them knowing it. The most common and most common thing is that when we see something we like, our pupils will dilate unconsciously. This is understandable because after all, we see something we like. But there is a certain scientific basis for why our pupils dilate at normal times.

3. In addition to the influence of pathological factors, pupil dilation is sometimes also an instinctive protective reaction of the body. Sometimes, a person's psychological activities can also be guessed through changes in the pupil. Under normal circumstances, the pupil is a contractible hole in the iris of the eye, and it is round whether it is expanded or shrunk.