The pupil is a round hole in the iris of the eye, a kind of diaphragm that can change its diameter. Sensitive photoreceptors of the eye react with unimaginable accuracy to changes in the fluxes of light rays. Depending on the intensity of lighting, a special muscle reduces or increases the size of the hole, thereby regulating the amount of light that enters the inner shell - the retina. Changing the diameter of the pupil is one of the most important indicators of the function and general condition of the brain. Not without reason in any feature film dedicated to emergency medicine, you can see the doctor shining a narrow flashlight in the patient’s eye in order to cause a reflex narrowing of the pupil and assess the level of consciousness.
Changing the size of the pupil can be associated not only with the degree of illumination. For example, when a person sees something that causes increased interest, the pupil changes its size intensively.
If the pupils are dilated, the reasons for this may be the following: strong emotions, arousal, increased attention, pain, fear. But there is also a painful constant expansion, which ultimately leads to damage to the optic nerves.
Pupil and disease
Persistent dilated pupils doctors call mydriasis. This condition can be caused by drugs or potent chemicals (including drugs).
However, doctors say that if the pupils are dilated, the causes must be determined as quickly as possible. Mydriasis can cause injuries (both the eye itself and the brain), as well as stroke, epilepsy and a number of other diseases of the brain. However, at different ages, the causes of persistent pupil size changes are different. If the pupils are dilated in an adult, the causes of this phenomenon may lie in the lesions and diseases of the cerebral vessels.
But if this is observed in newborns and young children, one should not always worry. If dilated pupils in a child are noted, the causes of this phenomenon may lie in innate genetic features. It is noteworthy that in newborns, pupils are at all of different sizes. In most cases, do not worry. But if the pupil is dilated more than 1 mm and under the influence of light does not return to its original size, then this is an occasion to consult a doctor.
Mydriasis in a teenager is a sign of trouble
As mentioned above, drugs such as cocaine, LSD, marijuana, amphetamines and other deadly substances cause a change in pupil size. If dilated pupils in a teenager, the reasons for this are usually unpleasant. A persistent increase in pupil size in the direction of increase is considered as a physiological sign of drug use. However, parents and teachers should remember that the opposite phenomenon (persistent narrowing of the pupil) is also a sure sign of drug intoxication of the opiate group. In this case, the pupil is unusually narrow and does not expand at all, even in complete darkness. But even in adolescents, the pupils can be dilated due to illness. Do not forget that mydriasis allows you to suspect a disease of the nervous system or blood vessels. In addition, pupils of various sizes are an early sign of brain tumors or severe infection.
If you or your family have dilated pupils, the reasons must be identified as soon as possible. The wide pupils give the eyes beauty, but they can also signal distress and illness.