Effect of Central Corneal Thickness on Intraocular Pressure Measured by Three Tonometers in Normal Subjects

Objective To study the effect of central corneal thickness(CCT) on the intraocular pressure(IOP) measured by Icare rebound tonometer(Icare),Goldmann Applanation Tonometer(GAT) and Dynamic Contour Tonometry(DCT).Methods IOP of 99 normal persons(185 eyes) was measured using Icare,GAT and DCT.CCT was measured using NIDEK-UP-1000.ANOVA of repeated measurement data and multiple comparison was applied to compare the IOP values measured by Icare,GAT and DCT.The pair-wise correlation was evaluated by Pearson correlation analysis.The effect of CCT on IOP measured by Icare,GAT and DCT was assessed by Pearson correlation analysis and linear regression analysis.Results The mean IOPs measured by Icare,GAT and DCT were(16.89±3.57)mmHg(1mmHg=0.133kPa),(16.28±3.33)mmHg and(15.57±2.57)mmHg respectively(significantly different,F=8.042,P0.001).They had positive pair-wise correlations,the correlation coefficient(r) between Icare and GAT was 0.879(P0.001),r between Icare and DCT was 0.583(P0.001),and r between GAT and DCT was 0.678(P0.001).IOPs measured by Icare and GAT had positive correlation with CCT(r=0.478,P0.001;r=0.443,P0.001) and IOP measured by DCT had no significant correlation with CCT(r=0.100,P=0.175).The differences of measured IOPs between Icare and DCT,GAT and DCT were significantly correlated with CCT(both r=0.493,P0.001),and the difference of IOPs between Icare and GAT had no significant correlation with CCT(r=0.137,P=0.063).Conclusion In healthy eyes,CCT doesn't affect the IOP measurement by DCT,but has similar affection the IOP measurement by Icare and GAT.