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

• Essential Anisocoria
• Simple Anisocoria

What is Physiologic 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
• Physiologic Anisocoria is the most common type of anisocoria. In this type, the variation in pupil size between both the eyes is very minor (usually less than 1 mm difference)
• Physiologic Anisocoria usually does not cause any significant vision impairment. The condition can be intermittent or persistent. Occasionally, it can be temporary, resulting in self resolution without any treatment

Who gets Physiologic Anisocoria? (Age and Sex Distribution)

• Physiologic Anisocoria is the most common cause of unequal pupil size. It is estimated that 1 in 5 individuals among the general population may have the condition
• Individuals of any age category (both children and adults) may be affected
• 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 Physiologic Anisocoria? (Predisposing Factors)

• No clearly established risk factors are identified for Physiologic Anisocoria

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 Physiologic Anisocoria? (Etiology)

The cause of Physiologic Anisocoria is generally unknown.

• Anisocoria occurs due to damage or abnormal functioning of the nerves that control the pupil sizes; this results in unequally sized pupils
• Some believe that Physiologic Anisocoria is caused by “transient asymmetric supranuclear inhibition of the Edinger-Westphal nucleus that controls the pupillary sphincter”

(Source: Anisocoria, EyeWiki; https://eyewiki.aao.org/Anisocoria)

What are the Signs and Symptoms of Physiologic Anisocoria?

The characteristic feature of all forms of anisocoria is the difference in pupil sizes. The signs and symptoms of Physiologic Anisocoria may vary from one individual to another. In a vast majority of cases, the condition is mild.

• In Physiologic Anisocoria, the light reflection and near responses are usually preserved
• Also, in many individuals, the difference in pupillary sizes is nearly equal, both in dark and lighted environments
• Occasionally, the signs and symptoms may include:
  • Light sensitivity and glare from pupil dilation (mydriasis)
  • Impaired accommodation
  • Eye pain
  • Headache
  • Double vision
  • Blurry vision
  • Fatigue

How is Physiologic Anisocoria Diagnosed?

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

• Physical examination and medical history evaluation
• 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 a 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 Physiologic Anisocoria?

In a majority of cases, no significant complications of Physiologic Anisocoria may be noted. However, rarely, the condition can be intermittent or persistent.

How is Physiologic Anisocoria Treated?

Physiologic Anisocoria usually does not require any treatment. A self-resolution of the condition is noted in many cases, without the need for any treatment.

How can Physiologic Anisocoria be Prevented?

• It may be difficult to prevent Physiologic Anisocoria since the cause of the condition is unknown
• Undertaking early and adequate treatment of any health issues is important

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

The prognosis of Physiologic Anisocoria is generally excellent since it is a mild condition that does not present any significant signs and symptoms.

Additional and Relevant Useful Information for Physiologic Anisocoria:

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

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