Amphetamines (and other stimulants) actually cause the pupils to dilate (become large). If the caregiver at the nursing home had small "pinprick" pupils that means he is most likely using opiates like heroin; or he's possibly helping himself to some of the resident's opioid pain medications such as morphine, oxycodone, hydromorphone and fentanyl, which are commonly used to treat cancer pain and in end of life care.