Pupil constriction

Pupil constriction (also called pinpoint pupils or miosis) can be described as the reduction of the size of a person's pupils under normal lighting conditions. This typically decreases a person's ability to see in low light conditions.

Pupil constriction is most commonly induced under the influence of moderate dosages of opioid compounds, such as heroin, kratom, tramadol, and fentanyl.