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 ...

Our pupils’ fast response to light appears to occur even without input from the brain. For example, it is seen in people with damage to the visual cortex. Appearances can be deceptive, though.

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 ...

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.

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 ...

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) ...

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. ...

What pupil changes reveal. While we are all aware that pupils enlarge when we glimpse a person or something we adore, inexplicable changes in pupils might be your body's method of alerting you to ...

Meet two women with unusual ways of experiencing the world: One cannot revisualize people or events, while the other may imagine too much.