The Effect of Central Corneal Thickness on Tonometry

Central corneal thickness (CCT) affects IOP measurements and is an independent risk factor for the development of glaucoma. IOP measurements of all common tonometers, such as the Goldmann applanation tonometer, non-contact tonometer and rebound tonometer, are affected by CCT. Nomograms to correct IOP measurements according to CCT have been established. These nomograms lead to a reduction of the measurement error caused by CCT in groups of patients. However, one has to be aware of the fact that, in individuals, the correction of IOP measurements can even increase the deviation of the IOP measurement from the actual IOP. The effect of CCT on dynamic contour tonometry and IOP measured by ORA is negligible. CCT is an important parameter in glaucoma management and needs to be considered when interpreting IOP measurements. This can be done by using nomograms or by implementing CCT in the calculation of the individual target pressure.