The DGH Technology Pachette 3 Ultasonic Pachymeter measures the thickness of the cornea. After the installation of a topical corneal anesthetic, the doctor touches the instrument tip to the eye and the pachymeter determines the corneal thickness via ultrasonic sound waves. This is a very reliable and accurate way of determining corneal thickness and has the additional benefit of allowing the doctor to determine exactly where the measurement should be made. The doctor needs this information in cases where there is a suspicion that eye pressure measurements may not be accurate (thinner than average corneas will have pressure readings lower than true pressure, thicker than average corneas will have pressure readings higher than true pressure). Additionally, corneal thickness is needed in patients with keratoconus, a disease causing progressive thinning of the cornea, or in patients interested in LASIK.