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

Abstract

Purpose:  To investigate 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 subjects.

Methods:  IOP values of 135 eyes with normal corneas of 135 healthy volunteers were determined by DCT, NCT and by GAT. The CCT was measured using an ultrasonic pachymeter after all IOP determinations had been made.

Results:  When DCT measurements were compared (IOP = 17.52 ± 2.0-mmHg) with NCT measurements (IOP = 16.54 ± 2.77-mmHg) and GAT measurements (IOP =  15.07 ± 2.35-mmHg), DCT measurements were significantly higher than NCT and GAT (p < 0.001). There was a significant correlation between CCT with both NCT (r = 0.260, p = 0.003) and GAT measurements (r = 0.257, p = 0.005). There was a weak correlation that was not statistically significant between CCT and DCT (r = 0.160, p = 0.079).

Conclusion:  The IOP measurements with DCT seem to be less dependent on CCT. NCT appears to be more affected by variation in CCT than GAT.

Key words:

• corneal thickness
• Goldmann applanation tonometry
• intraocular pressure
• non‐contact tonometry
• Pascal dynamic contour tonometry

ACKNOWLEDGEMENTS

The study is registered at http://actr.org.au with the clinical trial registration ACTRN12607000411448.

The contents of this article were presented at the International Congress of Ophthalmology, Sao Paulo, Brazil, 19–24 February 2006.