GLAUCOMA

Pressure in the eyeball

Glaucoma is intraocular hypertension, or high pressure inside of the eyeball. High pressure can compress the optic nerve, which is pretty bad. If untreated it can lead to blindness. Glaucoma is caused by an obstruction of aqueous humor drainage. Glaucoma has two flavors. 

CHRONIC OPEN-ANGLE GLAUCOMA - the trabecular meshwork gets gunked up. This is the most common type of glaucoma (95%). It’s idiopathic. This causes the pressure inside the eye to gradually increase. It takes years. Initially there is peripheral vision loss. Eventually that progresses to central vision loss. Painless. Not curable, but it can be slowed down with medications. Medications come in the form of pills or eyedrops. Laser surgery to blast open the trabecular meshwork helps too! The mainstay of treatment is with medicated eye drops. Beta Blockers and Carbonic Anhydrase Inhibitors eye drops slow humor production. Prostaglandin Analogs increase the drainage (although they can turn the iris brown). Alpha Blockers do both! 

ACUTE CLOSED-ANGLE GLAUCOMA - the iris flops up and physically obstructs the trabecular meshwork. This is pretty rare. There is a rapid pressure buildup in the eye. It causes an abrupt onset of eye pain, eye redness, blurry vision, headache, nausea and visual halos. The pupil will be fixed and dilated and the cornea will become cloudy. Often precipitated by a sudden dilation of the pupil, either by a medication (epinephrine, atropine, etc) or simply by walking into a dark room (classically a movie theater). This is one of the few ophthalmological eye emergencies! If left untreated, it can rapidly progress to permanent blindness! You must consult an ophthalmologist! They use the same medications as open-angle. Iridotomy is a surgical technique where a laser blasts a hole in the iris. 

Diagnosis?

Easy to perform. Press the tip of a pressure-detecting probe, or “Tonopen,” against their eyeball, and it can measure the pressure inside. If the pressure is > 21 mmHg that means that there is glaucoma (you don’t have to memorize that number). On fundoscopy, you’ll see an increase in the cup-to-disc ratio, and “cupping.”