GLAUCOMA

Impaired flow of aqueous humor, lead increases intraocular pressure with optic disk atrophy and cupping.

Open/wide angle: Obstructed outflow, associated with myopia, elderly, and African-American race. It is more common, silent, and painless.

Closed/narrow angle: Obstruction of flow between iris and lens. The pressure buildup behind iris. Very painful, decrease vision, rock-hard eye, and frontal headache. It is an ophthalmology emergency. Do not give epinephrine.

Treatment:

Drugs	Mechanism	Side effects
α-agonist: Epinephrine Brimonidine	Decrease aqueous humor synthesis due to vasoconstriction. Decrease aqueous humor synthesis.	Mydriasis, stinging, do not use in closed-angle glaucoma. No pupillary or vision changes.
Β-blocker: Timolol, Betaxolol, Carteolol.	Decrease aqueous humor secretion	No pupillary or vision changes.
Diuretics: Acetazolamide	Decrease aqueous humor secretion due to decrease HCO3, via inhibition of carbonic anhydrasa.	No pupillary or vision changes.
Cholinomimetics: Direct( Pilocarpine, carbachol) Indirect(Physostigmine, Echothiophate)	Increase outflow of aqueous humor, contract ciliary muscle and open trabecular meshwork; use Pilocarpine in emergencies; very effective at opening meshwork into canal of Schlemm	Miosis, cyclospasm.
Prostaglandin: Latanoprost (FGF2α)	Increase outflow of aqueous humor	Darkens color of iris (browning).

 Aqueous Humor pathway.

                                                             














References:
First aid for USMLE step 1, 2011
Harrison'online.Principios de Medicina Interna.18 edition.
Manual Merck 10 edicion

Cliniguia. Actualización de diagnostico y tratamiento. 2007.

Vázquez Lima, M.J. Casal Codesido, J.R. Guía de actuación de urgencias. 3ra edición. 2010.