Pachymetry is a quick, painless test that measures the thickness of your cornea, the clear dome at the front of the eye. Corneal thickness is a simple number, but it plays an important role in several areas of eye care, which is why it's a routine part of many comprehensive eye exams at our practice.
How Pachymetry Is Performed
The most common method uses ultrasound: a small handheld probe is gently touched to the surface of the eye after numbing drops are applied, and the device calculates corneal thickness based on how quickly sound waves travel through the tissue. Some practices also use non-contact optical pachymetry, which measures thickness using light instead of touching the eye. Either way, the measurement itself takes only a few seconds per eye.
Why Corneal Thickness Matters
Corneal thickness is one of the factors used to interpret eye pressure readings accurately — a thinner or thicker than average cornea can affect how a tonometry reading should be understood, which matters for glaucoma risk assessment. Pachymetry is also an important measurement when evaluating candidacy for certain vision correction procedures, and it helps track corneal health in conditions that cause the cornea to thin or swell over time.
What to Expect
If ultrasound pachymetry is used, you may feel a brief, light touch on the surface of your eye after numbing drops take effect — this is not painful, though the sensation can feel unusual at first. There's no downtime afterward. Your provider will use the results alongside your other exam findings, including eye pressure measurements, to build a complete picture of your eye health.