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Anisocoria Medication

  • Author: Eric R Eggenberger, MS, DO, FAAN; Chief Editor: Edsel Ing, MD, FRCSC  more...
Updated: Jun 16, 2016

Medication Summary

Drugs commonly used in the diagnosis of anisocoria include cocaine, hydroxyamphetamine, and pilocarpine (0.1-1%).


Topical anesthetic agents

Class Summary

This agent is used for diagnostic testing to detect Horner syndrome.



Prevents norepinephrine reuptake and accordingly dilates eye with intact sympathetic nervous system supply. Decreases membrane permeability to sodium ions, which, in turn, inhibits depolarization and blocks conduction of nerve impulses.


Cholinergic agents

Class Summary

This agent is used for diagnostic testing related to tonic pupil (0.1% concentration) or pharmacologic dilation-induced anisocoria (1% concentration).

Pilocarpine ophthalmic (Isopto)


Does not normally constrict pupil; however, with tonic pupil, produces miosis due to cholinergic supersensitivity. Constricts normal pupil or mydriatic pupil due to oculomotor palsy; however, after pharmacologic dilation (eg, atropinelike agents), pilocarpine has no miotic effects.


Sympathomimetic agents

Class Summary

Hydroxyamphetamine is useful diagnostically to test integrity of the third-order sympathetic neuron.

Hydroxyamphetamine (Paredrine)


Dilates pupil if third-order sympathetic neuron intact, and fails to dilate pupil if third-order neuron impaired.


Alpha2-adrenergic agonist agent, ophthalmic

Class Summary

These agents decrease IOP by reducing aqueous humor production.

Apraclonidine (Iopidine)


Potent alpha-adrenergic agent selective for alpha2-receptors with minimal cross-reactivity to alpha1-receptors. Suppresses aqueous production. Reduces elevated, as well as normal, intraocular pressure (IOP) whether accompanied by glaucoma or not. Apraclonidine is relatively selective alpha-adrenergic agonist that does not have significant local anesthetic activity. Has minimal cardiovascular effects.

Due to the weak, direct alpha-1 and alpha-2 receptor agonist effect, apraclonidine may reverse the Horner anisocoria (no effect on normal pupil, but Horner syndrome-related denervation supersensitivity produces pupil dilation).

Contributor Information and Disclosures

Eric R Eggenberger, MS, DO, FAAN Professor, Vice-Chairman, Department of Neurology and Ophthalmology, Colleges of Osteopathic Medicine and Human Medicine, Michigan State University; Director of Michigan State University Ocular Motility Laboratory; Director of National Multiple Sclerosis Society Clinic, Michigan State University College of Human Medicine

Eric R Eggenberger, MS, DO, FAAN is a member of the following medical societies: American Academy of Neurology, American Academy of Ophthalmology, American Osteopathic Association, North American Neuro-Ophthalmology Society

Disclosure: Serve(d) as a speaker or a member of a speakers bureau for: Biogen; Genzyme; Novartis; Teva <br/>Received research grant from: Biogen; Genzyme; Novartis<br/>Received consulting fee from Biogen for consulting; Received consulting fee from Teva for consulting; Received consulting fee from Acorda for consulting; Received grant/research funds from Novartis for independent contractor; Received honoraria from Genentech for speaking and teaching; Received honoraria from Genzyme for speaking and teaching.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Jane W Chan, MD Professor of Neurology/Neuro-ophthalmology, Department of Medicine, Division of Neurology, University of Nevada School of Medicine

Jane W Chan, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Ophthalmology, American Medical Association, North American Neuro-Ophthalmology Society, Phi Beta Kappa

Disclosure: Nothing to disclose.

Chief Editor

Edsel Ing, MD, FRCSC Associate Professor, Department of Ophthalmology and Vision Sciences, University of Toronto Faculty of Medicine; Consulting Staff, Hospital for Sick Children and Sunnybrook Hospital

Edsel Ing, MD, FRCSC is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, American Society of Ophthalmic Plastic and Reconstructive Surgery, Royal College of Physicians and Surgeons of Canada, Canadian Ophthalmological Society, North American Neuro-Ophthalmology Society, Canadian Society of Oculoplastic Surgery, European Society of Ophthalmic Plastic and Reconstructive Surgery, Canadian Medical Association, Ontario Medical Association, Statistical Society of Canada, Chinese Canadian Medical Society

Disclosure: Nothing to disclose.

Additional Contributors

James Goodwin, MD Associate Professor, Departments of Neurology and Ophthalmology, University of Illinois College of Medicine; Director, Neuro-Ophthalmology Service, University of Illinois Eye and Ear Infirmary

James Goodwin, MD is a member of the following medical societies: American Academy of Neurology, Illinois State Medical Society, North American Neuro-Ophthalmology Society, Royal Society of Medicine

Disclosure: Nothing to disclose.

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Flowchart to assist in the diagnosis of anisocoria (modified with permission from Thompson and Pilley)
Horner syndrome secondary to carotid dissection. Note that degree of anisocoria is relatively mild in room light. Also, see the image below of the same patient.
Horner syndrome due to carotid dissection. Note the increase in degree of anisocoria under dark conditions.
Typical pupil in third nerve palsy, with mydriasis. Note the inability to adduct the right eye. This patient has a skull-based meningioma that is compressing the right third nerve. At rest, complete ptosis is present in the right eye; however, lid elevation with attempted adduction of the right eye is noted, which is consistent with aberrant regeneration.
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