Which intravenous agent reduces intraocular pressure by decreasing vitreous or aqueous volume in acute angle-closure glaucoma?

Which intravenous agent reduces intraocular pressure by decreasing vitreous or aqueous volume in acute angle-closure glaucoma?

• A. Dexamethasone
• B. Acetazolamide
• C. Mannitol
• D. Furosemide

Answer: (C)

In acute angle-closure glaucoma, the fastest way to lower pressure is by reducing the fluid volume inside the eye. An intravenous osmotic agent like mannitol raises the plasma osmolality, drawing water out of the vitreous and ocular tissues into the bloodstream. This directly shrinks the vitreous volume, rapidly lowering intraocular pressure. Other agents work differently: acetazolamide reduces the production of aqueous humor rather than pulling fluid from the vitreous, dexamethasone is mainly anti-inflammatory and doesn’t provide rapid IOP reduction, and furosemide’s diuretic effect isn’t reliably effective for rapidly lowering IOP in this setting. Thus, the IV osmotic agent that decreases vitreous volume to drop intraocular pressure is mannitol.

In acute angle-closure glaucoma, the fastest way to lower pressure is by reducing the fluid volume inside the eye. An intravenous osmotic agent like mannitol raises the plasma osmolality, drawing water out of the vitreous and ocular tissues into the bloodstream. This directly shrinks the vitreous volume, rapidly lowering intraocular pressure. Other agents work differently: acetazolamide reduces the production of aqueous humor rather than pulling fluid from the vitreous, dexamethasone is mainly anti-inflammatory and doesn’t provide rapid IOP reduction, and furosemide’s diuretic effect isn’t reliably effective for rapidly lowering IOP in this setting. Thus, the IV osmotic agent that decreases vitreous volume to drop intraocular pressure is mannitol.