Q:

What are the causes of pinpoint pupils?

A:

Pinpoint pupils, or abnormal miosis, occur as the result of stimulation to the parasympathetic side of the autonomous nervous system. According to WebMD, drug use, exposure to organophosphates and intracranial hemorrhaging all cause both pupils to shrink. Inflammation and Horner's syndrome usually cause only one pupil to shrink, but not both.

MedlinePlus states that an overdose of opiates is the most common cause of abnormal miosis affecting both eyes. Opiates include prescription pain medications, such as Fentanyl, morphine and methadone, and illicit drugs, such as heroin. The combination of pinpoint pupils and depressed breathing strongly suggests an overdose.

Organophosphates cause pupils to constrict, whether as the result of accidental poisoning or deliberate exposure, as in the case of terrorist use or intent to self-harm. Exposure may occur by ingestion, inhalation or through the skin. MedlinePlus cites accidental exposure to pesticides as the most common cause of exposure to organophosphates, with most occurring in developing countries and rural areas.

WebMD adds that intracranial hemorrhaging of the pons causes abnormal miosis. The pons, located near the brain stem, may hemorrhage as the result of traumatic injury to the area or in patients who have a history of vascular disease and stroke. Administering Narcan to a patient who has pinpoint pupils and an altered mental state helps determine whether drug overdose or hemorrhaging is the cause. If the altered mental state does not respond to Narcan, a pontine hemorrhage is likely.

Less common causes of abnormal miosis include Horner's syndrome and neurosyphilis.

Learn More

Related Questions

  • Q:

    What is normal pupil size?

    A:

    The normal range for pupil size is between 2 and 5 millimeters, although the lighting plays a large part in that spectrum. As people age, their pupils tend to become smaller, according to About.com.

    Full Answer >
    Filed Under:
  • Q:

    What is an optical migraine?

    A:

    An optical migraine is medically known as an "ocular migraine," a headache that causes temporary blindness or vision loss, along with or following a migraine headache. These episodes are also called retinal, ophthalmic, or monocular migraines. The blindness or vision loss generally lasts less than an hour, according to WebMD.

    Full Answer >
    Filed Under:
  • Q:

    How does an astigmatism affect your eyes?

    A:

    Astigmatism is a condition where the lens or the cornea develops an irregularity, changing its shape from the normal curve. Part of the surface becomes flatter, causing light to focus irregularly on the retina. This creates blurry vision, and requires a special type of corrective lens.

    Full Answer >
    Filed Under:
  • Q:

    What is the cause of a bubble on my eye?

    A:

    A bubble on the eyeball commonly indicates swollen conjunctiva due to allergic conjunctivitis, a condition in which the eye becomes inflamed in response to external irritants, such as animal dander and outdoor pollens, according to the American Association for Pediatric Ophthalmology and Strabismus. Additional irritants include house dust and mold.

    Full Answer >
    Filed Under:

Explore