Meperidine's pupil response differs from most opioids and causes which ocular effect?

Meperidine's pupil response differs from most opioids and causes which ocular effect?

• A. Mydriasis
• B. Miosis
• C. No Pupil Change
• D. Ptosis

Answer: (A)

Pupil size is a useful clue about opioid effects because most opioids cause miosis, a pinpoint pupil, by increasing parasympathetic activity in the eye. Meperidine is different. It has some antimuscarinic properties and its metabolite can cause central nervous system stimulation, which reduces parasympathetic influence on the iris sphincter and can even promote sympathetic-like effects. That combination leads to pupil dilation rather than constriction. So the ocular effect you’d expect with meperidine is pupil dilation (mydriasis). Miosis is what you’d typically see with other opioids, no pupil change would mean no observable pupil size effect, and ptosis is a different eyelid issue that isn’t about the pupil size itself.

Pupil size is a useful clue about opioid effects because most opioids cause miosis, a pinpoint pupil, by increasing parasympathetic activity in the eye. Meperidine is different. It has some antimuscarinic properties and its metabolite can cause central nervous system stimulation, which reduces parasympathetic influence on the iris sphincter and can even promote sympathetic-like effects. That combination leads to pupil dilation rather than constriction. So the ocular effect you’d expect with meperidine is pupil dilation (mydriasis).

Miosis is what you’d typically see with other opioids, no pupil change would mean no observable pupil size effect, and ptosis is a different eyelid issue that isn’t about the pupil size itself.