Corneal thickness: It's time we all get rid of the correction factor from the glaucoma equation!

T measurement of central corneal thickness (CCT) by pachymetry plays an integral part of the contemporary glaucoma workup. It is one of the relatively simple and straightforward ancillary tests performed today in the clinic. Clinicians have embraced this measure since the emergence of understanding its impact on the accuracy of tonometry such as Goldmann applanation tonometry (GAT). GAT, which is the gold standard of tonometry, assumes a central cornea thickness of approximately 520 μ. Any deviation from this assumption will result in an inaccurate intraocular pressure (IOP) measurement by as much as 7 mmHg/100 μ as evident by the experimental studies.[1] We now know that CCT varies greatly among healthy normal individuals. Differences in corneal thicknesses exist with various factors such as age, gender, race, as well as other environmental factors.[2] Therefore, the accuracy of tonometry in daily practice is affected which can lead to erroneous IOP estimates in certain situations with misclassification of patients in terms of glaucoma risk.