Which drug draws fluid out of the eyeball to reduce intraocular pressure?

• A. Mannitol
• B. Atropine
• C. Diamox
• D. Timolol

Answer: (A)

Lowering intraocular pressure can be achieved by pulling fluid out of the eye with an osmotic agent. Mannitol does exactly that: it’s an intravenous osmotic diuretic that raises the plasma osmolality, creating a gradient that draws water from ocular tissues such as the vitreous body into the bloodstream. This rapid shift reduces the volume inside the eye and drops the pressure quickly, which is particularly useful in acute glaucoma or before eye surgery.

The other drugs work by different mechanisms. Diamox and Timolol decrease the production of aqueous humor, helping to lower pressure but not by extracting fluid from the eye. Atropine dilates the pupil and can worsen or precipitate angle-closure glaucoma, so it’s not used to reduce intraocular pressure.