For example, using alcohol, marijuana, or cocaine can cause dilated pupils, and opiates can cause pupillary constriction or dilation. These effects are usually symmetrical, but they may be unequal.

There are several opioid emergency situations ... Slow, shallow or absent breathing Pinpoint pupils: The person’s pupils (the dark circle in the center of the eye) may appear very small.

Recent systematic review and network meta-analysis aimed to compare different nociception monitors in quantifying nociception ...