This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: A.N.S., Subject name: Pharmacology
Ocular effects that include mydriasis and fixed far vision are characteristic of 
Select and explain. 
A. mecamylamine, B. neostigmine, C. phentolamine, D. phenylephrine
A: mecamylamine
Answer: A: mecamylamine 
Explanation: Mydriasis and fixed far vision can be due to either muscarinic receptor antagonists or ganglionic blockade. Because no M blockers are listed, the correct answer is mecamylamine. Alpha agonists (phenylephrine) have no effects on the focus of the eye. The cholinesterase inhibitor (neostigmine) and alpha blocker (phentolamine) cause miosis. Ocular effects of the beta blocker (timolol) are restricted to decreased formation of aqueous humor by the ciliary epithelium.