How it is measured
Ultrasound pachymetry touches a small probe to the numbed cornea and times an echo from the back surface, giving a single central reading in a second. Optical methods (Scheimpflug tomography and anterior segment OCT) measure without contact and produce a map of thickness across the entire cornea, locating the thinnest point, which is often not at the center. Practices often use the map for planning and the probe for confirmation.
Pachymetry and laser vision correction
LASIK removes tissue in proportion to the prescription and spends about 100 microns on the flap, and a safe amount of cornea must remain afterward. Thickness therefore decides whether LASIK is possible, whether PRK or SMILE, which leave the cornea stronger (PRK by avoiding a flap and leaving more stroma, SMILE by using a small incision instead of a flap), are safer, or whether the EVO ICL, which removes none, is the right answer. Thickness is read alongside shape, because a thin cornea with an irregular shape is at higher risk than a thin regular one.
Pachymetry and glaucoma
Eye pressure is measured by flattening the cornea, and a thick cornea resists more, reading high, while a thin one reads low. Pachymetry helps interpret the reading. Independently, thin corneas are associated with a higher risk of developing glaucoma from ocular hypertension, and thickness is one of the factors used to estimate that risk and decide on treatment.
Pachymetry in corneal disease
Keratoconus thins the cornea at the cone, and the thinnest point tracked over time is one of the measures of progression that guide cross-linking. Fuchs dystrophy and other endothelial failure thicken the cornea as it swells, and increasing thickness signals decompensation and the timing of transplantation. Before cataract surgery in Fuchs dystrophy, thickness helps predict whether the cornea will tolerate the operation.
Is this right for your eyes?
Nothing on this page is a diagnosis. Whether this is the right choice for you is decided by a full examination at one of our 4 offices: Pasadena, Huntington Beach, Woodland Hills and Beverly Hills.
About this content: This page was written with the assistance of AI tools and reviewed for medical accuracy by Dr. Bavand Youssefzadeh, DO. It is general information, not medical advice, and does not replace an eye examination. Individual results vary. Read our medical disclaimer.
