This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Mannitol decreases the intraocular pressure by ? 
Select and explain. 
A. Withdrawing water from vitreous, B. Increasing uveoscleral outflow, C. Increasing aqueous through trabecular meshwork, D. Inhibiting the enzyme carbonic anhydrase in the ciliary body
A: Withdrawing water from vitreous
Answer: A: Withdrawing water from vitreous 
Explanation: Ans. is 'a' i.e., Withdrawing water from vitreous By osmotic action mannitol encourages movement of water from aqueous humour --> decrease. Mannitol is used in angle closure (narrow angle, acute congestive) glaucoma. Treatment of acute congestive glaucoma o Definitive therapy is surgery (laser iridotomy) Drugs are used to decrease the i.o.t. during an acute attack. o Approch is : Sta i.v. mannitol or i.v. acetazolamide When i.o.t. stas falling, sta topical pilocarpine or b -blocker (timolol). Apraclonidine/latanoprost may be added. Once i.o.t. is reduced, surgery is done.