17/01/2026
Pupil Disorders:
What Your Eyes May Be Telling You
The pupil not only regulates the amount of light entering the eye... it can also be a window into your neurological and ocular health. Here are some of the most common abnormalities:
Anisocoria
When one pupil is larger than the other.
It can be benign, but it can also be associated with neurological problems.
Miosis
An abnormally small pupil. It can be caused by medications, substance use, or Horner's syndrome.
Mydriasis
An abnormally dilated pupil. It can be related to trauma, medications, or nervous system disorders.
Corectopia
The pupil is displaced or irregularly shaped.
It is usually associated with trauma or eye surgery.
Marcus Gunn Pupil
An afferent pupillary defect: indicates that one eye does not correctly transmit the visual signal to the brain.
Coloboma
A "keyhole" shaped pupil, usually congenital.
If you notice changes in the size, shape, or reaction of your pupils, don't ignore them. A timely eye exam can make all the difference.
Dr. Carlos Moreno de Anda
Ophthalmology | Evidence-Based Eye Health