Table of ContentsView AllTable of ContentsSymptomsCausesDiagnosisTreatmentPrognosis
Table of ContentsView All
View All
Table of Contents
Symptoms
Causes
Diagnosis
Treatment
Prognosis
Withmiosis, the eye’s dark center (thepupil) is smaller than it should be. Usually, the pupil expands and contracts to allow less or more light into the eye as needed. But with miosis, the pupil remains at just 2 millimeters or less, even in conditions that usually would call for allowing more light into the eye to see optimally. This may affect one or both eyes.
In this article, you will learn whatmiosis(pupil constriction) is, what symptoms to watch for, possible causes, what to know about treatment, and more.
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Miosis Symptoms
Detecting whether you have a constricted pupil may or may not be obvious. The type of symptoms you have can vary depending on what’s causing the miosis. Some signs to watch for include the following:
While the pupils usually contract in very bright light, they may also be small due to conditions affecting your health. A variety of conditions can cause pinpoint pupils. At the root can be medications, substance overuse, disease, or physical trauma.
Medication Effects
Drug Overuse
Overuse or misuse of certain substances can also cause pupils to constrict. Drugs that can cause this effect include:
Toxins
Coming into contact with certain environmental toxins may also cause pupil constriction. For example, organophosphate pesticides can cause miosis.Contact with plants such as Jimsonweed or belladonna, as well as atropine, hyoscine, scopolamine, and hyoscyamine, can all lead to pinpoint pupils.
Health Conditions
Certain health conditions can also cause constricted pupils. Inflammation in the eye can lead to what’s known as acute anterioruveitis, which is a sudden onset of symptoms at the front of the eye. Conditions that can cause this include:
Horner’s Syndrome
An injury to the nerves responsible for sending the signal to widen or narrow the pupil can causeHorner’s syndrome. These sympathetic nerves are located in the brain, neck, and upper chest.
These same nerves are associated with lifting the eyelid. The pupil on the same side that the injury occurred on will be affected. Also, sometimes the lid on that side will droop.
Trauma
Head or neck trauma or a bleed in the brain from a broken blood vessel, such as a brain aneurysm, can potentially lead to a pinpoint pupil. These are serious issues and should be immediately addressed.
Meiosis vs. MiosisThough pronounced the same, these words have very different meanings. “Meiosis” is a term describing cell division that forms egg and sperm cells that have half the number of chromosomes as other body cells. “Miosis” means the pupil of the eye is constricted.
Meiosis vs. Miosis
Though pronounced the same, these words have very different meanings. “Meiosis” is a term describing cell division that forms egg and sperm cells that have half the number of chromosomes as other body cells. “Miosis” means the pupil of the eye is constricted.
If the situation calls for it, you may be asked to undergo neuroimaging tests such as eithermagnetic resonance imaging (MRI)or acomputed tomography (CT) scan.
If a healthcare provider thinks the situation is not just eye related, you may be asked to undergo some general testing, such as blood work or urinalysis.
Your healthcare provider will recommend treatment based on your diagnosis.
If you have an infection, your eye doctor will prescribe medication to alleviate this. If a medication itself is the source of the constricted pupils, then your healthcare provider may either adjust the dose or select another medication without the same side effects.
If a substance use disorder is at the root of the constricted pupils, you may be directed to a treatment program that will help you to overcome it.
If you have acute anterior uveitis, your ophthalmologist or optometrist may recommend treatment with steroids to alleviate inflammation.Also, they may prescribe eye drops to help relax your eye muscles and enlarge your pupils.
Any underlying infection will also be treated with either antibiotics or antifungal medication. In rare cases, immunosuppressants may be prescribed for those who don’t respond to the usual treatment.
Summary
While the dark pupil at the center of the eye usually expands and contracts depending upon the amount of light, sometimes the pupil becomes constricted and stays that way even when the lighting changes.
The cause of this pupillary constriction can involve illness, injury, medication or substance use, or contact with toxins. Because causes can be so varied, diagnosis may affect just the eye or may involve more extensive testing. Any treatment you receive will address the underlying cause so the pupil can respond as needed.
14 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Mount Sinai.Horner syndrome.American Optometric Association.Anterior uveitis.New York University Langone Health.Medication for glaucoma.MedlinePlus.Clonidine.Pula JH, Kao AM, Kattah JC.Neuro-ophthalmologic side-effects of systemic medications.Curr Opin Ophthalmol. 2013;24(6):540-549. doi:10.1097/01.icu.0000434557.30065.a7 (using link to full text rather than doi that only goes to paywall summary)Ghassemi Toussi A, Zare G.Miosis, bradypnea and loss of consciousness with several compacted solid materials in rectum and colon in abdominal X-ray.APJMT. 2014;3(1). doi:10.22038/apjmt.2014.2471Busardò FP, Jones AW.GHB pharmacology and toxicology: acute intoxication, concentrations in blood and urine in forensic cases and treatment of the withdrawal syndrome.Curr Neuropharmacol. 2015;13(1):47-70. doi:10.2174/1570159X13666141210215423Bey T, Patel A.Phencyclidine intoxication and adverse effects: a clinical and pharmacological review of an illicit drug.Cal J Emerg Med. 2007;8(1):9-14. (although older, am allowing this as the best authoritative source)Erdem U, Gundogan FC, Dinc UA, Yolcu U, Ilhan A, Altun S.Acute effect of cigarette smoking on pupil size and ocular aberrations: a pre- and postsmoking study.J Ophthalmol. 2015;2015:625470. doi:10.1155/2015/625470American Academy of Ophthalmology.Pharmacologic dilation of pupil.American Academy of Ophthalmology.Acute anterior uveitis.American Association for Pediatric Ophthalmology and Strabismus.Anisocoria and Horner’s syndrome.Johns Hopkins.Pupillary disorders including anisocoria.National Health Services.Treatment uveitis.
14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Mount Sinai.Horner syndrome.American Optometric Association.Anterior uveitis.New York University Langone Health.Medication for glaucoma.MedlinePlus.Clonidine.Pula JH, Kao AM, Kattah JC.Neuro-ophthalmologic side-effects of systemic medications.Curr Opin Ophthalmol. 2013;24(6):540-549. doi:10.1097/01.icu.0000434557.30065.a7 (using link to full text rather than doi that only goes to paywall summary)Ghassemi Toussi A, Zare G.Miosis, bradypnea and loss of consciousness with several compacted solid materials in rectum and colon in abdominal X-ray.APJMT. 2014;3(1). doi:10.22038/apjmt.2014.2471Busardò FP, Jones AW.GHB pharmacology and toxicology: acute intoxication, concentrations in blood and urine in forensic cases and treatment of the withdrawal syndrome.Curr Neuropharmacol. 2015;13(1):47-70. doi:10.2174/1570159X13666141210215423Bey T, Patel A.Phencyclidine intoxication and adverse effects: a clinical and pharmacological review of an illicit drug.Cal J Emerg Med. 2007;8(1):9-14. (although older, am allowing this as the best authoritative source)Erdem U, Gundogan FC, Dinc UA, Yolcu U, Ilhan A, Altun S.Acute effect of cigarette smoking on pupil size and ocular aberrations: a pre- and postsmoking study.J Ophthalmol. 2015;2015:625470. doi:10.1155/2015/625470American Academy of Ophthalmology.Pharmacologic dilation of pupil.American Academy of Ophthalmology.Acute anterior uveitis.American Association for Pediatric Ophthalmology and Strabismus.Anisocoria and Horner’s syndrome.Johns Hopkins.Pupillary disorders including anisocoria.National Health Services.Treatment uveitis.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Mount Sinai.Horner syndrome.American Optometric Association.Anterior uveitis.New York University Langone Health.Medication for glaucoma.MedlinePlus.Clonidine.Pula JH, Kao AM, Kattah JC.Neuro-ophthalmologic side-effects of systemic medications.Curr Opin Ophthalmol. 2013;24(6):540-549. doi:10.1097/01.icu.0000434557.30065.a7 (using link to full text rather than doi that only goes to paywall summary)Ghassemi Toussi A, Zare G.Miosis, bradypnea and loss of consciousness with several compacted solid materials in rectum and colon in abdominal X-ray.APJMT. 2014;3(1). doi:10.22038/apjmt.2014.2471Busardò FP, Jones AW.GHB pharmacology and toxicology: acute intoxication, concentrations in blood and urine in forensic cases and treatment of the withdrawal syndrome.Curr Neuropharmacol. 2015;13(1):47-70. doi:10.2174/1570159X13666141210215423Bey T, Patel A.Phencyclidine intoxication and adverse effects: a clinical and pharmacological review of an illicit drug.Cal J Emerg Med. 2007;8(1):9-14. (although older, am allowing this as the best authoritative source)Erdem U, Gundogan FC, Dinc UA, Yolcu U, Ilhan A, Altun S.Acute effect of cigarette smoking on pupil size and ocular aberrations: a pre- and postsmoking study.J Ophthalmol. 2015;2015:625470. doi:10.1155/2015/625470American Academy of Ophthalmology.Pharmacologic dilation of pupil.American Academy of Ophthalmology.Acute anterior uveitis.American Association for Pediatric Ophthalmology and Strabismus.Anisocoria and Horner’s syndrome.Johns Hopkins.Pupillary disorders including anisocoria.National Health Services.Treatment uveitis.
Mount Sinai.Horner syndrome.
American Optometric Association.Anterior uveitis.
New York University Langone Health.Medication for glaucoma.
MedlinePlus.Clonidine.
Pula JH, Kao AM, Kattah JC.Neuro-ophthalmologic side-effects of systemic medications.Curr Opin Ophthalmol. 2013;24(6):540-549. doi:10.1097/01.icu.0000434557.30065.a7 (using link to full text rather than doi that only goes to paywall summary)
Ghassemi Toussi A, Zare G.Miosis, bradypnea and loss of consciousness with several compacted solid materials in rectum and colon in abdominal X-ray.APJMT. 2014;3(1). doi:10.22038/apjmt.2014.2471
Busardò FP, Jones AW.GHB pharmacology and toxicology: acute intoxication, concentrations in blood and urine in forensic cases and treatment of the withdrawal syndrome.Curr Neuropharmacol. 2015;13(1):47-70. doi:10.2174/1570159X13666141210215423
Bey T, Patel A.Phencyclidine intoxication and adverse effects: a clinical and pharmacological review of an illicit drug.Cal J Emerg Med. 2007;8(1):9-14. (although older, am allowing this as the best authoritative source)
Erdem U, Gundogan FC, Dinc UA, Yolcu U, Ilhan A, Altun S.Acute effect of cigarette smoking on pupil size and ocular aberrations: a pre- and postsmoking study.J Ophthalmol. 2015;2015:625470. doi:10.1155/2015/625470
American Academy of Ophthalmology.Pharmacologic dilation of pupil.
American Academy of Ophthalmology.Acute anterior uveitis.
American Association for Pediatric Ophthalmology and Strabismus.Anisocoria and Horner’s syndrome.
Johns Hopkins.Pupillary disorders including anisocoria.
National Health Services.Treatment uveitis.
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