Other medicines that get in the eyes, including medicine from asthma inhalers, can change pupil size. The use of eye drops is a common cause of a harmless change in pupil size. Unequal pupil sizes of more than 1 mm that develop later in life and do not return to equal size may be a sign of an eye, brain, blood vessel, or nerve disease. If there are no other symptoms and if the pupils return to normal, then it is nothing to worry about. If other family members also have similar pupils, then the pupil size difference could be genetic and is nothing to worry about.Īlso, for unknown reasons, pupils may temporarily differ in size. Most often, the diameter difference is less than 0.5 mm, but it can be up to 1 mm.īabies born with different sized pupils may not have any underlying disorder. Slight differences in pupil sizes are found in up to 1 in 5 healthy people. It gets larger in dim light and smaller in bright light. The pupil is the black part in the center of the eye. These eyeglasses darken automatically in brightly lit environments to protect your eyes from harmful UV rays and blue light especially with larger pupils that do not react normally to light.Anisocoria Enlargement of one pupil Pupils of different size Eyes/pupils different sizeĪnisocoria is unequal pupil size. For increased comfort, your doctor may prescribe photochromic lenses. If your eye exams result in mild anisocoria normal reaction of your pupils to light, there may be nothing to worry about. If you notice any changes in your pupils, consult your doctor immediately especially if you experience other symptoms such as: This is known as the paralysis of the oculomotor nerve that causes the affected eye to have a dilated pupil resulting in anisocoria along with ptosis. This generally occurs more in women and affects only one eye.

Anisocoria caused by this condition have pupils that react poorly to light because of damaged nerve fibers that control the eye muscles. Normal pupils dilate in dim light within five seconds while a pupil affected by Horner’s syndrome takes 10 to 20 seconds to dilate in dim lighting.Īdie’s tonic pupil. This condition may be differentiated from simple anisocoria by how quickly the pupil constricts and dilates. In rare cases, anisocoria caused by iritis may remain after the iritis has been treated. Iritis may be caused by an eye infection, trauma, and underlying inflammatory disease. It is a form of uveitis, or the inflammation of the eyes, characterized by photophobia, eye redness, pain, constriction of the pupil on the affected eye, and inflammatory cells in the eye.

Pathologic anisocoria causes differences in pupil sizes due to underlying conditions such as: Motion sickness and nausea from chemotherapy medications along with some glaucoma eye drops such as transdermal scopolamine patches can also cause anisocoria. Selective serotonin reuptake inhibitors (SSRIs) used to treat depression have been identified as potential causes of pharmacologic anisocoria. This is inequality in pupil size that occurs as a side effect of a medication. This type of anisocoria may also be caused by congenital anomalies in the structure of the iris which include:Īniridia – complete or partial absence of the iris in one eyeĮctopic pupil – displacement of the pupil and lensĬoloboma – gap in the iris which gives off a “keyhole” or “cat-eye” appearance Mechanical anisocoria is a result of damage to the iris or its surrounding structures caused by trauma, tumors, complications of eye surgery, angle-closure glaucoma, uveitis, iritis, and other inflammatory conditions.

Simple anisocoria may be intermittent, constant, or sometimes goes away on its own – although the exact cause is still unknown. The difference in pupil size is approximately 1 mm or less and both pupils respond normally to light. It is a harmless condition that affects around 20% of the population. In the mirror, the pupil of the eye appears as a black circle in the middle of the iris (the colored part of the eye). Simple anisocoria, also known as essential anisocoria or physiologic anisocoria, is the most prevalent type of anisocoria. Pupillary Disorders Including Anisocoria. However, if your anisocoria happens all of a sudden, this can be a symptom of a serious condition.

In common cases, anisocoria is usually benign and does not need serious concern. Anisocoria is a condition where the two pupils are unequal in size and may not respond normally to light.

Causs of unequal pupil size