How to judge diseases through pupils
Unequal pupil size on both sides is common in cerebral hemorrhage, cerebral thrombosis and brain tumor.
Pupils are dilated, which are more common in craniocerebral trauma, cerebrovascular disease, severe epidemic encephalitis B, purulent meningitis and so on.
Pupillary shrinkage is more common in alcohol (also known as alcohol) poisoning, sleeping pills poisoning, pontine tumor and pontine hemorrhage in the elderly, and can also be seen in diabetes (because the relaxation and contraction of pupils are regulated by autonomic nerves, diabetes leads to autonomic nerve damage, which can affect the relaxation and contraction function of pupils. Clinically, it is found that the pupil of diabetic patients is smaller than that of normal people. Organophosphorus poisoning can also lead to pupil contraction, and morphine poisoning can lead to needle pupil.
Arrow pupil: the size of the left and right pupils is very different, or they are not round pupils, which are common in lateral branches of spinal cord, cerebrospinal syphilis and herpes zoster.
How to judge the size of the pupil, whether the two sides are equal, and whether the pupil is sensitive to light?
Pupil: The diameter of the pupil is about 3-4mm under ordinary light. It is generally considered that the pupil diameter is less than 2mm and greater than 5mm is mydriasis.
Pupil response to light: refers to the response of pupil contraction caused by light stimulation, which can be divided into direct reflection to light and indirect reflection to light. The contraction of photosensitive pupil becomes the direct reflection of light, while the contraction of non-photosensitive pupil is called the indirect reflection of light. Any damage on the conduction path will lead to the disappearance of pupil reflection and pupil dilation.
Equal size and circle: Adult pupil diameter is generally 2-4mm, which is a regular circle with equal size on both sides, and the difference between the two sides is less than 0.25 mm. However, if the difference between the pupil diameters of both eyes is 0.25-0.5mm, there is no abnormality in pupil reaction and drug experiment, which can be considered as physiological pupil inequality.
So besides diseases, what other factors affect pupil size?
The size of the pupil is dominated by sympathetic and parasympathetic nerves. There are two kinds of tiny muscles in the iris, one is called the pupil sphincter, which surrounds the pupil and has a width less than1mm. It is responsible for pupil contraction and is innervated by parasympathetic nerve in oculomotor nerve. The other is called mydriatic muscle, which is radially arranged in the iris and is responsible for pupil dilation and is dominated by sympathetic nerves. These two muscles coordinate with each other, restrict each other and contract one by one to adapt to various environments.
The size of the pupil can control the amount of light entering the eye. Pupils, like the aperture of a camera, can be narrowed or enlarged with the intensity of light. When taking pictures, we all know that the aperture should be turned down when the light is strong, and turned up when the light is dark, so that enough light can always enter the camera through the aperture. The pupil also has this function, but its adaptation to light intensity is automatic. Through the adjustment of the pupil, always keep a proper amount of light into the eyes, so that the image of the object falling on the retina is clear, and there will be no excessive light burning the retina.
Pupils can vary widely. In extreme contraction, the diameter of human pupil can be less than 1mm, and in extreme expansion, it can be greater than 9 mm. The size of pupil not only changes with the intensity of light, but also is related to factors such as age, refraction and physiological state.
Pupil changes in patients with craniocerebral injury are of great significance to the diagnosis of intracranial hematoma. How to judge the pupil size, before or after flashlight irradiation?
As can be seen from the above, the pupil itself will be adjusted according to the intensity of external light. When the light is strong, the pupil will become smaller, and when the light is weak, the pupil will become larger. This is self-protection for the eyes. For example, the pupil will become larger during normal sleep, but it will become smaller after irradiation. For patients with craniocerebral injury, the size should be judged by the diameter of the pupil after narrowing. Clinically, we often see that the pupil of patients with craniocerebral injury can only be narrowed after repeated irradiation, as long as it is sensitive to light reflection after repeated irradiation.