Common Causes
The etiology of anisocoria is complex, ranging from benign to potentially life-threatening causes. Potential etiologies of anisocoria include systemic drug use, topical ophthalmic drug use, headaches, trauma, ophthalmologic diseases, and autonomic ganglion pathology.
Related Conditions
Based on our data, physiologic anisocoria is more prevalent under varied lighting conditions, and clinicians and researchers may benefit from capturing pupil measurements in standardized light conditions.
What is the pathophysiology of anisocoria?
Physiological Anisocoria Physiologic anisocoria is usually defined as a pupillary inequality of 0.4 mm, seldom greater than 0.8 mm, not due to a secondary cause. If the anisocoria is physiologic, the difference in pupil sizes should remain equal in dim and bright lights.
Is physiologic anisocoria more prevalent under different lighting conditions?
What is the normal range of anisocoria?
What causes physiologic anisocoria?
Generally, anisocoria is caused by impaired dilation (a sympathetic response) or impaired constriction (a parasympathetic response) of pupils. An injury or lesion in either pathway may result in changes in pupil size.
How can you tell if anisocoria is a physiologic?
If anisocoria remains the same in both lighting conditions, and the difference between pupil sizes is no more than 2 mm, the aetiology is likely to be physiological. The presence of ptosis and/or extraocular muscle involvement suggests a pathological process regardless of the magnitude of anisocoria.
Does physiological Anisocoria go away?
Physiological anisocoria may be temporary or permanent, depending on individual cases. About 15–30% of the population experiences physiological anisocoria. The difference between the pupil sizes is more or less constant, even when the light changes, and is not usually of concern.
Can physiological Anisocoria come and go?
While small differences in pupil size are normal and can even come and go (physiologic anisocoria), constant and significant differences in pupil sizes may be a sign of damage to the nerves that control the pupils or to the brain.
Can anisocoria be caused by anxiety?
Although the autonomic system is usually balanced, stress can lead to increased autonomic asymmetry.
What is the most common cause of anisocoria?
Anisocoria can be caused by a lot of conditions in your body, injuries, traumas and even some medicines. Some of the most common causes include: Migraine headaches. Glaucoma.
What neurological conditions cause anisocoria?
CausesAneurysm in the brain.Bleeding inside the skull caused by head injury.Brain tumor or abscess (such as, pontine lesions)Excess pressure in one eye caused by glaucoma.Increased intracranial pressure, because of brain swelling, intracranial hemorrhage, acute stroke, or intracranial tumor.More items...•
Is unequal pupil size an emergency?
For new uneven pupil size that is related to new double vision, eyelid droopiness or head, neck or eye pain, it is best to be evaluated in the emergency room.
What drugs can cause anisocoria?
Severe illnesses and various anticholinergic and sympathomimetic drugs may also cause anisocoria and mydriasis. The authors cite that anisocoria and mydriasis have occurred with fluvoxamine, bupropion, paroxetine, and sertraline.
What is physiological anisocoria?
Physiological anisocoria. From Wikipedia, the free encyclopedia. Jump to navigation Jump to search. Physiological anisocoria is when human pupils differ in size. It is generally considered to be benign, though it must be distinguished from Congenital Horner's syndrome, pharmacological dilatation or other conditions connected to ...
How many mm is an anisocoria?
At any given eye examination, up to 41% of healthy patients can show an anisocoria of 0.4 mm or more at one time or another. It can also occur as the difference between both pupils varies from day to day.
Is anisocoria a genetic disorder?
When detected during childhood, without any other symptoms and when other disorders are discarded through clinical tests, it should be considered a developmental or genetic phenomenon. Asymmetric pupil or dyscoria, potential causes of anisocoria, refer to an abnormal shape of the pupil which can happens due to developmental and intrauterine anomalies. When light is shined in the abnormal eye and it remains dilated then it’s a pathological small pupil.
What is anisocoria?
Anisocoria is a condition characterized by unequal pupil sizes. It is relatively common, and causes vary from benign physiologic anisocoria to potentially life-threatening emergencies. Thus, thorough clinical evaluation is important for the appropriate diagnosis and management of the underlying cause.
Why is anisocoria greater in the dark?
Anisocoria is greater in the dark due to a defect in the pupillary dilator response secondary to lesions along the sympathetic trunk. Central or first-order lesions are often caused by stroke, lateral medullary syndrome, neck trauma or demyelinating disease.
What causes an unequal pupil size?
Generally, anisocoria is caused by impaired dilation (a sympathetic response) or impaired constriction (a parasympathetic response) of pupils. An injury or lesion in either pathway may result in changes in pupil size. Physiologic (also known as simple or essential) anisocoria is the most common cause of unequal pupil sizes, ...
What causes adie's tonic pupil?
Causes include Adie’s tonic pupil, oculomotor nerve palsy, traumatic injury to the iris, or pharmacologic dilation from mydriatics/cycloplegics (atropine, tropicamide, cyclopentolate), or cocaine. The use of pilocarpine can be diagnostic in this setting.
What is Horner's syndrome?
Horner’s syndrome (oculosympathetic palsy) is classically described by the triad of ptosis, miosis, and anhidrosis, although clinical presentations may vary. Anisocoria is greater in the dark due to a defect in the pupillary dilator response secondary to lesions along the sympathetic trunk.
What are some examples of congenital anomalies in the iris?
Examples include aniridia, coloboma, and ectopic pupil. Mechanical anisocoria is an acquired defect that results from damage to the iris or its supporting structures.
Where does the afferent light stimulus go?
Afferent light stimulus is received by retinal ganglion cells whose axons traverse as the optic nerve, optic chiasm, and optic tract to eventually synapse at the pretectal nuclei of the dorsal midbrain at the level of the superior colliculi.
Types of Anisocoria
Characterization of anisocoria includes unequal pupil sizes. While the condition is common, the causes may or may not be benign .
Accompanying Symptoms of Anisocoria
Many people do not realize that their pupils vary in size. It may become apparent when they compare old and newer photos of themselves.
How is Anisocoria Diagnosed?
If you think you have anisocoria, you should speak with your ophthalmologist or healthcare professional.
When is Anisocoria Normal? When is Treatment Necessary?
Not all types of anisocoria will require treatment or indicate a serious health condition.
How to Correct Different Pupil Sizes
Correcting different pupil sizes will depend on the type of anisocoria you have.
Is Anisocoria Preventable?
Anisocoria may be preventable in some cases. For example, in pharmacologic anisocoria, stopping the administration of the pharmacologic agent causing the issue could provide relief.
Why does anisocoria diminish in bright light?
The anisocoria usually diminishes slightly in bright light, perhaps because the smaller pupil reaches the zone of mechanical resistance first , giving the larger pupil a chance to make up the size difference (117).
What is the anisocoria of a pupil?
The anisocoria is 1 mm or less. “Inequality of pupil size becomes clinically observable when the difference between pupils is about 3 mm. In dim light or darkness, almost 20% of the normal population hasan anisocoria of 0.4 mm or more at the moment of examination.
Can anisocoria be traced back to childhood?
In the latter case, the anisocoria usually can be traced back to infancy or early childhood. Value of old photographs in the assessment of anisocoria. A, This 3-year-old boy was noted by his parents to have intermittent anisocoria, with the right pupil larger than the left.
Is pupillary inhibition normal?
The pupillary reactions to light and darkness are normal. Instead, it is presu med to occur becausethe supranuclear inhibition of the parasympathetic pupilloconstrictornuclei in the midbrain is not balanced with anymore precision than is necessary for clear, binocular vision.It is unrelated to refractive error.
Does anisocoria vary with time?
The prevalence of anisocoria did not vary with the time of day, from day to day, or from week to week, nor was it influenced by the sex, age, or iris color of the subject.”4. Anisocoria Examination. Tapsell S – https://www.youtube.com/watch?v=jgVJyEOXVvM.
What are the different types of anisocoria?
Types. Physiological ani socoria is the most common type of anisocoria. There are three types of anisocoria: Physiological anisocoria : This is when the pupils are naturally different sizes. It is the most common type of anisocoria, and the difference between the pupil sizes is no more than 1 millimeter.
What is the difference between mechanical and pathological anisocoria?
Mechanical anisocoria: This type of anisocoria is the result of physical damage to the eye, such as an injury or a condition that causes inflammation to the eye. Pathological anisocoria: This type is when the difference in pupil size comes from one of the following: a disease affecting the iris, or colored area.
What tests are used for anisocoria?
They will usually use physical tests and scans, such as CT scans or MRIs, as soon as possible.
What to do if you have anisocoria?
If the damage is due to an underlying condition, such as uveitis or glaucoma, a doctor will develop an individualized treatment plan. If a person’s medication is causing anisocoria, a doctor may recommend a different drug. The symptoms of tonic pupil often subside with glasses and a prescription for pilocarpine.
Is anisocoria permanent?
Physiological anisocoria may be temporary or permanent, depending on individual cases. About 15–30%. Trusted Source. of the population experiences physiological anisocoria. The difference between the pupil sizes is more or less constant, even when the light changes, and is not usually of concern.
Can you get a CT scan for anisocoria?
With pathological anisocoria, a doctor may recommend a CT scan to rule out dangerous underlying causes. People with physiological anisocoria do not usually need treatment, as it is typically harmless. Mechanical anisocoria may require surgery to correct the damage a trauma has caused.
Is anisocoria a condition?
Anisocoria is a symptom of many conditions but is not a condition on its own. In this article, learn about the possible causes for pupils of different sizes, as well as when to see a doctor.