What are the other Names for this Condition? (Also known as/Synonyms)

• Chemicals-Induced Anisocoria
• Drug-Induced Anisocoria
• Medication-Induced Anisocoria

What is Pharmacologic Anisocoria? (Definition/Background Information)

• Anisocoria is a relatively common eye condition that is characterized by “unequal pupil sizes”. In other words, the size of the left and right pupils vary in dimension (different sizes). Based on the underlying cause, anisocoria is classified into several types
• Pharmacologic Anisocoria is caused by certain medications, such as atropine, nasal vasoconstrictors, or clonidine, that may be taken for other health conditions. The condition may be also caused by illegal drugs, chemicals, and non-pharmaceutical medications

Who gets Pharmacologic Anisocoria? (Age and Sex Distribution)

• Anisocoria is reportedly common among the general population
• Individuals of any age category (both children and adults) may be affected by Pharmacologic Anisocoria
• Both males and females may be affected
• Worldwide, individuals of all races and ethnicity are prone to developing the condition

What are the Risk Factors for Pharmacologic Anisocoria? (Predisposing Factors)

The key risk factor for Pharmacologic Anisocoria is the use of certain medications (to treat other health conditions) and other substances/agents that lead to the eye condition as an unintended side effect or complication. These include:

• Anticholinergics such as:
  • Atropine
  • Cyclopentolate
  • Homatropine
  • Scopolamine (including scopolamine patches)
  • Tropicamide
• Glycopyrrolate antiperspirants
• Nasal vasoconstrictors
• Plants and herbs such as:
  • Angel’s trumpet
  • Blue nightshade
  • Jimson weed
• Pilocarpine
• Sympathomimetics such as:
  • Adrenaline
  • Clonidine
  • Phenylephrine
• Insecticides
• Prostaglandins
• Opioids

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Pharmacologic Anisocoria? (Etiology)

Anisocoria occurs due to damage or abnormal functioning of the nerves that control the pupil sizes; this results in unequally sized pupils.

• Pharmacologic Anisocoria may be caused by a variety of medications, chemical substances, native medicines, or even following exposure to certain insecticides. It result in different (non-uniform) dilatation of the pupils
• The mechanism of development of anisocoria depends on the type of medication/substance; usually the eye muscles and associated nerves are damaged by these drugs/substances

What are the Signs and Symptoms of Pharmacologic Anisocoria?

The characteristic feature of all forms of anisocoria is the difference in pupil sizes. The signs and symptoms of Pharmacologic Anisocoria may vary from one individual to another. It depends on several factors, such as the severity of the condition and exposure/usage (dose) of the substance/medication.

The signs and symptoms of Pharmacologic Anisocoria may include:

• Light sensitivity and glare from pupil dilation (mydriasis)
• Impaired accommodation
• Eye pain
• Headache
• Double vision
• Blurry vision
• Fatigue
• Numbness
• Droopy eyelids
• Impaired coordination or ataxia

How is Pharmacologic Anisocoria Diagnosed?

Pharmacologic Anisocoria may be diagnosed by the following observations and tests:

• Physical examination and medical history evaluation (including the use of any medications, herbals, or exposure to chemical substances)
• Assessment of signs and symptoms
• General eye exam:
  • Examination of the eye in both dark and lighted environments
  • Using topical eye drops to determine the pupillary size reaction is also helpful in arriving at possible cause
• Fundoscopic (ophthalmoscopic) examination by an eye specialist, who examines the back part of the eye (or the fundus)
• Visual acuity test using a special and standardized test chart (Snellen chart)
• Slit-lamp examination
• Visual evoked potential (VEP) test
• Fundus fluorescein angiography
• Optical coherence tomography (OCT) of eye
• Imaging studies including CT and MRI scans of the head and neck region

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Pharmacologic Anisocoria?

The complications of Pharmacologic Anisocoria may include:

• Difficulty in performing simple tasks under bright lights
• Vision impairment that may be irreversible
• Decreased quality of life
• Treatment related complications

How is Pharmacologic Anisocoria Treated?

• Pharmacologic Anisocoria usually gets better on discontinuing the medications/agents that triggered anisocoria
• Close follow-up and periodic visits to the healthcare provider is important

How can Pharmacologic Anisocoria be Prevented?

It may be difficult to prevent some cases of Pharmacologic Anisocoria. However, the following factors may help reduce one’s risk for developing the same:

• When possible, causative medications may be discontinued and/or alternative medication prescribed
• Avoid the use of recreational drugs
• Avoid eye exposure to chemicals and insecticides
• Undertaking early and adequate treatment of any health issues is important

What is the Prognosis of Pharmacologic Anisocoria? (Outcomes/Resolutions)

• The prognosis for Pharmacologic Anisocoria is usually good, upon immediate discontinuation of the medication (or stoppage of exposure to the substance) and adequate treatment of the eye condition
• In most cases, the prognosis can be improved by removing the offending agent

Additional and Relevant Useful Information for Pharmacologic Anisocoria:

Please visit our Eye & Vision Health Center for more physician-approved health information:

https://www.dovemed.com/health-topics/vision-center/