Organophosphate poisoning is typically associated with which pupil change?

Organophosphate poisoning is typically associated with which pupil change?

• A. Dilated Pupils
• B. Constricted Pupils
• C. No Pupillary Change
• D. Fixed Pupillary Response

Answer: (B)

Organophosphate poisoning causes overstimulation of the parasympathetic system because acetylcholinesterase is blocked, leading to excess acetylcholine at muscarinic receptors. In the eye, this excess acetylcholine makes the iris sphincter contract, producing pupil constriction (miosis). This constricted-pupil finding is a hallmark of the cholinergic toxidrome seen with organophosphate exposure. Dilated pupils would suggest sympathetic dominance or an anticholinergic effect, no pupil change would be inconsistent with this toxin’s effects, and a fixed pupil points to structural injury rather than a chemical toxidrome.

Organophosphate poisoning causes overstimulation of the parasympathetic system because acetylcholinesterase is blocked, leading to excess acetylcholine at muscarinic receptors. In the eye, this excess acetylcholine makes the iris sphincter contract, producing pupil constriction (miosis). This constricted-pupil finding is a hallmark of the cholinergic toxidrome seen with organophosphate exposure. Dilated pupils would suggest sympathetic dominance or an anticholinergic effect, no pupil change would be inconsistent with this toxin’s effects, and a fixed pupil points to structural injury rather than a chemical toxidrome.