Final answer:
Yes, OP poisoning causes miosis, which is pupil constriction due to the overstimulation of muscarinic receptors by accumulated acetylcholine. Atropine, a treatment for OP poisoning, causes pupil dilation by blocking these receptors, affirming that OP poisoning has the opposite effect.
Step-by-step explanation:
The question revolves around whether organophosphate (OP) poisoning causes miosis (pupil constriction). The answer is Yes. Organophosphates are cholinesterase inhibitors that cause an accumulation of acetylcholine, resulting in overstimulation of muscarinic receptors, which leads to symptoms such as miosis. On the other hand, atropine is a muscarinic antagonist that causes mydriasis (pupil dilation) by blocking muscarinic receptors, which is why it is used as a treatment for OP poisoning. By knowing that atropine is used to counteract the effects of OP poisoning, we can infer that it is treating the opposite condition caused by OP poisoning, which is miosis.