Pachymetry is the measurement of the thickness of the cornea. This special medical device is used to help with the diagnosis of glaucoma. One of the causes of glaucoma is having too much pressure inside the eye, which damages the optic nerve and causes loss of sight. When we measure the pressure inside the eye with tonometry, the readings can be affected by how thick or thin the cornea is; thick corneas can make the pressure measured artificially high and thin corneas measure it artificially low. Having thinner corneas is a risk factor for glaucoma, making pachymetry an important part of a glaucoma work-up.