Your pupil expands and contracts as a normal part of its function. One of the most common reasons for this change is to allow your pupil to expand to take in more light in low-light situations and to contract to protect the eye in bright light. However, when the pupils remain constricted regardless of the amount of light in the room, this is referred to as pinpoint pupils, and it is a cause for concern.
Diagnosis of Pinpoint Pupils
Since the eye naturally constricts in bright light, diagnosing pinpoint pupils requires creating a dark environment and watching how the pupil reacts. The quickest way to do this in a conscious person is to have him close his eyes for a few seconds. When the person opens his eyes a normal pupil will have expanded and you can watch it constrict in the light. In a person with pinpoint pupils, the pupil won't expand when the eye is closed and you won't see a change in size when he opens his eyes. If the person is unconscious, cover his eyes with your hand or an opaque cloth and remove it to simulate the eye opening and closing.
Causes of Pinpoint Pupils
Pinpoint pupils are most typically a result of opiate use or overdose, a hemorrhage in the pons region of the brain or chemical exposure. Signs of opiate use include finding drug paraphernalia or needle marks on the body. A pontine hemorrhage is usually caused by a head trauma. Chemical exposure includes organophosphates and nerve agents. Both of these substances are found in many fertilizers and herbicides. If a person in an agricultural setting has pinpoint pupils, chemical exposure is likely the reason.
Returning the Pupils to Normal
Treating pinpoint pupils depends on the cause, but in all cases the person needs to be taken to the emergency room. For opiate or chemical exposure, the person will need to have his system cleansed with a counter-agent to remove the toxins. For hemorrhages, the emergency doctors will first aim to relieve any pressure on the brain to prevent further damage to it. Time and recovery from the cause is the only way to return pinpoint pupils to normal.
Benefits of Pinpoint Pupils
While having pinpoint pupils doesn't benefit a person directly, it is an important diagnostic tool for emergency technicians and doctors. Because a limited number of things cause pinpoint pupils, emergency doctors and technicians can make a diagnosis quicker, which means a faster treatment time.