Miosis

Definition

Miosis is pupillary constriction (less than 2 mm in bright light, less than normal size in dim light). Pinpoint pupils can signal opioid toxicity, certain CNS lesions, or cholinergic effects.

Causes

• Opioid use/overdose (pinpoint pupils classic)
• Cholinergic drugs (pilocarpine, organophosphates)
• Pontine hemorrhage
• Horner's syndrome (miosis + ptosis + anhidrosis)
• Iritis
• Senile miosis (aging)

Nursing Interventions

Assess for opioid overdose. Pinpoint pupils + respiratory depression + altered LOC. Administer naloxone 0.4 to 2 mg IV/IM, repeat every 2 to 3 minutes; support ventilation.

NCLEX Relevance

Pinpoint pupils = opioid toxicity classic triad.