pinpoint pupils

What are pinpoint pupils?

Pupils that are abnormally small under normal lighting conditions are called pinpoint pupils. Another word for it is myosis, or miosis.

The pupil is the part of your eye that controls how much light gets in.

In bright light, your pupils get smaller (constrict) to limit the amount of light that enters. In the dark, your pupils get bigger (dilate). That allows more light in, which improves night vision. That’s why there’s an adjustment period when you enter a dark room. It’s also the reason your eyes are a bit sensitive after your eye doctor dilates them on a bright day.

Pupil constriction and dilation are involuntary reflexes. When a doctor shines a light into your eyes after an injury or illness, it’s to see if your pupils are reacting normally to light.

Other than lighting, pupils can change size in reaction to other stimuli. For instance, your pupils might get bigger when you’re excited or on heightened alert. Some drugs can cause your pupils to get bigger, while others make them get smaller.

In adults, pupils normally measure between 2 and 4 millimetersTrusted Source in bright light. In the dark, they usually measure between 4 and 8 millimeters.

What are common causes of pinpoint pupils?

One of the most likely reasons someone might have pinpoint pupils is the use of narcotic pain medications and other drugs in the opioid family, such as:

codeine

fentanyl

hydrocodone

oxycodone

morphine

methadone

heroin

Other possible causes of pinpoint pupils include:

Bleeding from a blood vessel in the brain (intracerebral hemorrhage): Uncontrolled high blood pressure (hypertension) is the most common reason for this.

Horner syndrome (Horner-Bernard syndrome or oculosympathetic palsy): This is a group of symptoms caused by a problem in the nerve pathway between the brain and one side of the face. A stroke, a tumor, or spinal cord injury can lead to Horner syndrome. Sometimes the cause can’t be determined.

Anterior uveitis, or inflammation of the middle layer of the eye: This may be due to trauma to the eye or the presence of something foreign in the eye. Other causes include rheumatoid arthritis, mumps, and rubella. Often, the cause can’t be determined.

Exposure to chemical nerve agents such as sarin, soman, tabun, and VX: These are not naturally occurring substances. They’re made for chemical warfare. Insecticides can also cause pinpoint pupils.

Certain prescription eye drops, such as pilocarpine, carbachol, echothiophate, demecarium, and epinephrine, can also cause pinpoint pupils.

Less common causes include:

certain medications, such as clonidine for blood pressure, lomotil for diarrhea, and phenothiazines for certain psychiatric conditions like schizophrenia

illicit drugs such as mushrooms

neurosyphilis

deep sleep

Symptoms associated with pinpoint pupils

Pinpoint pupils are a symptom, not a disease. Accompanying symptoms may offer a clue about what’s causing the problem.

If you take opioids, you might also experience:

sleepiness

nausea and vomiting

confusion or lack of alertness

delirium

difficulty breathing

Symptoms will depend on how much of the drug you take and how often you take it. In the longer term, opioid use can reduce lung function. Signs that you might be addicted to opioids include:

intense cravings for more of the drug

needing a bigger dose to achieve the desired effect

trouble at home, on the job, or financial problems due to drug use

Intracerebral hemorrhage may cause severe headache, nausea, and vomiting, and may be followed by loss of consciousness.

If your pinpoint pupils are due to Horner syndrome, you might also have a drooping eyelid and decreased sweating on one side of your face. Babies with Horner syndrome might have one iris that is lighter in color than the other.

Additional symptoms of anterior uveitis include redness, inflammation, blurred vision, and light sensitivity.

Nerve agents may also cause tearing, vomiting, seizures, and coma.

Insecticide poisoning causes salivation, tearing, excessive urination, defecation, and vomiting

Treatment

There’s no treatment specifically for pinpoint pupils because it’s not a disease. However, it can be a symptom of one. The diagnosis will guide your treatment options.

In the event of an opioid overdose, emergency personnel can use a drug called naloxone to reverse the life-threatening effects of opioids. If you’re addicted, your doctor can help you stop safely.

In some cases, intracerebral hemorrhage may require surgical intervention. Treatment will also include measures to keep your blood pressure under control.

There’s no treatment for Horner syndrome. It may get better if the cause can be determined and treated.

Corticosteroids and other topical ointments are typical treatments for anterior uveitis. Additional steps may be necessary if the cause is determined to be an underlying disease.

Insecticide poisoning can be treated with a drug called pralidoxime (2-PAM