Because of total internal reflection. Light from the trabecular meshwork reflects back into the eye at the tear-film-air interface. You need a gonio lens.

Normal corneal thickness is about 540 microns, thus this patient has thick corneas. Real pressure is probably close to 13.

PXF is a common condition where flaky material forms on the surface of the lens. It can cause glaucoma and lens dislocations during surgery.

PDS is a type of glaucoma that occurs from pigment rubbing off the back of the iris. The pigment can clog the trabecular meshwork.

This occurs from neovascular blood vessels forming on the iris and growing up into the trabecular meshwork … blocking outflow of aqueous.

The ISNT rule describes the thickness of the neuro-retinal rim in healthy eyes: the optic nerve is thickest Inferiorly and thinnest Temporally.

Farsightedness, family history of glaucoma attack, medications that dilate pupil, medications that dilate the pupil, prior attack in other eye.

High eye pressure, optic nerve cupping, race, family history, and thin corneas.

Applanation works by measuring the amount of pressure it takes to flatten a defined area of cornea. Like kicking a car tire to estimate pressure.

Normal corneal thickness is about 540 microns. Corneal thickness is needed to evaluate glaucoma risk and to calibrate pressure readings.

Normal eye pressure is usually considered 10 to 21 mmHg.

Chronic (open-angle) glaucoma is common and occurs from chronically high pressure. Acute (angle-closure) glaucoma is rare and a major emergency.

Aqueous is produced by the ciliary body. It fills the posterior chamber, through the pupil into the anterior chamber. Aqueous drains out the “TM” into the canal of Schlemm.

Glaucoma is gradual death of the optic nerve, often associated with high intraocular pressure.