The pachymeter is a handheld instrument which uses ultrasound to measure the thickness of the cornea. Persons with too thin corneas are not good candidates for laser surgery. Intraocular pressure readings for glaucoma screening can be inaccurate if a persons cornea is much thinner or much thicker than average. There are several corneal diseases which cause the cornea to thin over time. The pachymeter allows us to accurately assess all of these conditions.