Effect of corneal thickness on intraocular pressure measurements with the Pascal dynamic contour tonometry, Canon TX-10 non-contact tonometry and Goldmann applanation tonometry in healthy subjects

We investigated the effects of central corneal thickness (CCT) on intraocular pressure (IOP) measurements of the Pascal dynamic contour tonometry (DCT), Canon TX-10 non-contact tonometry (NCT), and Goldmann applanation tonometry measurements (GAT) in healthy eyes. The IOP measurements were taken in random order to guarantee an independent measurement of all instruments. Each measurement performed by the same physician (AP) three times consecutively with each of the three devices in the same day. The mean of these three measurement was recorded. After each measurement on each instrument a rest period of 10 min was allowed to minimize the tonographic effects of applanation tonometry. For DCT, three readings of 'good' quality were saved (score = 3 on a scale up to 5, as recommended by the manufacturer) Subsequently, another physician (RAY) carried out ultrasonic pachymetry (UP-1000 Ultrasonic pachymeter, Nidek Co, Japan) The mean of 5 measurements was recorded for analysis. Recent evidence has confirmed the wide variation in corneal thickness and raised the possibility that corneas that are thicker or thinner than average might be associated with clinically significant overestimates or underestimates of IOP