ophthalmology

Central Corneal Thickness Correction for Goldmann IOP

Central corneal thickness (CCT) affects Goldmann applanation readings, but published correction formulae disagree and none improves glaucoma risk prediction (OHTS). CCT is recorded and used as a risk factor alongside IOP.

Used in: Acute Red Eye

Result

Goldmann readings are most accurate at a central corneal thickness (CCT) of about 520 µm (Ehlers 1975); thinner corneas tend to read low and thicker ones high, but published corrections disagree (Doughty & Zaman's meta-analysis: 1.1 mmHg per 10 % difference in CCT in healthy eyes, 2.5 mmHg in eyes with chronic disease) and none is validated — in the Ocular Hypertension Treatment Study, IOP adjusted by five published formulae predicted glaucoma no better than the measured IOP (Brandt 2012). Record the measured IOP and use CCT as a separate risk factor: a CCT of 555 µm or less carried about three times the risk of glaucoma of a CCT over 588 µm (OHTS), and NICE NG81 weighs CCT with IOP, family history and life expectancy. Normal CCT in white adults is about 535 µm (473–597 µm).

References

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pathways

Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.

References

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