Opioids usually make a person’s pupils constrict. This is when the black part at the center of the eye gets smaller, reducing the amount of light that gets inside. Typically, pupil constriction ...

Usually, your pupils dilate and constrict together and are the same size as each other. Unequal pupils happen when one pupil is not reacting to light as it should. If the iris muscle is paralyzed ...

Small, constricted pupils can be a side effect of opioid use. Learn about other signs to watch for and how to bring up your concerns in a helpful, compassionate way.

A function of the body that happens automatically without a thought, was considered to be impossible to replicate at will. Yet a 23-year-old student in Germany can shrink and enlarge his pupils on ...

The medical term for pupils of different sizes is anisocoria. Find out about the possible causes of anisocoria here, as well as when to seek emergency treatment.

But your pupils may also change size based on injuries, drug use, or even sexual arousal. Here are seven reasons your pupils may be dilated, and when you should see a doctor. 1.

Dilated pupils, or pupils that are larger than normal, have many causes. Injury, a medical condition, or drug use are a few causes of this condition. (Photo Credit: Moment/Getty Images) ...

New pupillometry research reveals how post-traumatic stress disorder (PTSD) may affect both branches of the autonomic nervous system. By measuring how someone's pupils dilate and constrict in ...

For years, scientists thought that pupils â those tiny black circles in the middle of our eyes â dilate and become large when we inhale and constrict to their smallest size when we exhale. ...