It is when the pupils remain contracted regardless of a greater or lesser luminosity, it is what we call pinpoint pupils or pathological miosis. Causes: a) Excessive drug use: intoxication by these substances, such as heroin, methadone, or cocaine, affect our central nervous system causing bilateral miosis and can even cause cardiorespiratory arrest. In the case of heroin intoxication, the pupils become so miotic, contracted, that they are often called pin points. b) Horner syndrome causes the pupil to contract, the eyelid to droop, and sweating to decrease as a result of a stroke, tumor, or spinal cord injury. c) Hemorrhage in the brainstem bridge of the brain d) Due to exposure to chemical substances: it usually occurs in those jobs that come into continuous contact with fertilizers or herbicides in the field of agriculture.