What Is Anisocoria?

Anisocoria is when your eye’s pupils are not the same size. The pupil allows light to enter the eye so that you can see.

Anyone can have pupils that differ in size with no problems. In fact, one out of five people have pupils that are normally different sizes.

Sometimes, though, having uneven pupil size can be a symptom of a serious eye problem. People who may get anisocoria include those who have:

  • a nervous system problem
  • a history of damage to the eye
  • risk of having a stroke
  • a viral infection
  • Adie’s tonic pupil (when one pupil does not respond to light as well as the other pupil)