dilate

The pair made up soon afterwards even though the punch had permanently damaged the pupil in Bowie's left eye, meaning it would no longer dilate even in bright lights, giving it the impression of being a different colour from his right eye.

However, in their new study published in the peer-reviewed journal Attention, Perception & Psychophysics, the researchers reported that a person's pupils also dilate when they are concentrating on tasks.

As a result, blood flow to that area increases dramatically as blood vessels dilate, causing pain and swelling.

A typical remedy is to stretch or dilate the urethra, a minimally invasive procedure that is often performed with general anesthesia, Dr. Lepor said.

Longer-term use of a catheter would only be needed if doctors were unable to sufficiently dilate the urethra.