Glaucoma
Central corneal thickness helps us interpret eye pressure readings and your individual risk profile.
Interpreting corneal thickness accurately
Pachymetry: Measurement of corneal thickness
Pachymetry measures corneal thickness in micrometres. It helps interpret pressure readings, assess structural changes and plan surgery safely.
Understanding the procedure
One measurement, several clinical uses.
An unusually thin or thick cornea can affect pressure readings. Its thickness is not a simple correction factor: we assess it alongside the method, optic nerve, pressure history and other risks.
Optical tomography creates a complete thickness map without contact. Ultrasound pachymetry briefly touches the numbed cornea with a probe to take a local measurement.
- Measurement parameter
- Corneal thickness in micrometers
- Methods
- Optical or ultrasound measurement
- Contact
- Depending on the method
- When it is used
- Glaucoma, keratoconus, surgical planning
Used where needed
When is the corneal thickness needed?
A central reading or a full thickness map may be useful, depending on the clinical question.
Keratoconus
The thinnest point, thickness distribution and changes over time are key parts of tomography.
Refractive surgery
Before laser correction, we check that there is enough stable corneal tissue.
Corneal disorders
Swelling or thinning can be recorded objectively and compared over time.
Step by step
This is how the thickness is measured.
The method depends on the device and clinical question.
Optical measurement
You focus on a target while the device calculates cross-sections and a thickness map without contact.
Prepare ultrasound
For contact measurements, drops numb the eye’s surface.
Repeat measurements
We check alignment and consistent readings, avoiding excessive pressure from the probe.
Assessing the results together
We assess corneal thickness and shape, pressure measurements and the other findings together.
Understanding the results
No fixed pressure correction from a table.
Some methods of measuring eye pressure may give higher readings with a thick cornea and lower readings with a thin one. The cornea’s biomechanical properties also affect the result. Simply adding or subtracting a fixed amount therefore does not reliably establish the true pressure inside the eye.
For follow-up checks, the method, device and measurement conditions should be as consistent as possible.
Well prepared
How to prepare for your visit
- Remove contact lenses as instructed
- Continue using eye drops as prescribed
- Bring previous pachymetry or tomography measurements
- After contact measurements, do not rub your eye while it is numb
Frequently asked questions
Clear, concise answers.
Is a thin cornea sick?
Not necessarily. Corneal thickness varies between people. Shape, structure, changes over time and the clinical question all matter.
Is my intraocular pressure being corrected mathematically?
We consider corneal thickness, but do not replace a full assessment with a fixed numerical correction.
Is the measurement painful?
Optical measurements are non-contact. For ultrasound, anaesthesia means the brief contact is normally painless.
Medical note
This page cannot replace an eye examination. Your symptoms, history and findings determine which tests are useful and how their results should be interpreted.
Medical basics
Sources and further information.
Related topics
All non-surgical eye care services