How is CCT used to correct IOP?

Correction: for every 10 microns above 520 microns, subtract approximately 0.7 mmHg from measured IOP. For thin corneas, add approximately 0.7 mmHg per 10 microns below 520. Multiple correction formulas exist (Ehlers, Shah); no universally agreed formula.

Why does CCT matter in ocular hypertension (OHT)?

OHTS: CCT 600 microns) may cause overestimated IOP, leading to false OHT diagnoses. True IOP may be normal in these patients.

When is CCT measured?

CCT measured at: glaucoma/OHT diagnosis, pre-LASIK (to ensure adequate stromal bed), and post-LASIK (when IOP may be falsely low). Ultrasonic pachymetry is gold standard; optical coherence pachymetry (Cirrus, Pentacam) is faster and contactless.

Central Corneal Thickness IOP Correction

Correct Goldmann applanation tonometry IOP for central corneal thickness (CCT). Standard CCT is 520-540 microns; thin corneas underestimate true IOP; thick corneas overestimate IOP.

Use the full interactive calculator below, or

Central Corneal Thickness IOP Correction

Frequently Asked Questions

How is CCT used to correct IOP?

Why does CCT matter in ocular hypertension (OHT)?

When is CCT measured?