Title: Effect of Central Corneal Thickness on Intraocular Pressure Readings by Goldmann Applanation Tonometer and Non Contact Tonometer
Authors: Chitra Raghavan, Swathi Subramanian, V Sahasranamam, Beena Thankappan
DOI: https://dx.doi.org/10.18535/jmscr/v6i3.189
Abstract
Purpose: To study the effect of CCT on IOP readings obtained by NCT and GAT across varying IOP ranges, and to correlate the IOP readings obtained by GAT and NCT.
Methods: 230 eyes were included in this cross sectional study. CCT, IOP by GAT and NCT were measured. Correlation and linear regression between CCT and IOP obtained by GAT and NCT were analysed.
Results: The mean IOP obtained by GAT was 15.64 ± 6.27 mm Hg, and that by NCT was 16 mmHg. The mean CCT measured was 537.6 ± 39.3 μm.IOP by GAT showed a significant positive correlation with CCT (r = 0.78 and p < 0.001). IOP by GAT changes by 1.25 mm Hg per 10 μm change in CCT. IOP by NCT also shows positive correlation with CCT (r = 0.72, p < 0.001).IOP by NCT changes by 1.21 mm Hg per 10 μm change in CCT.IOP measured by GAT and NCT showed a significant positive correlation, with highest correlation in the IOP range of 11 – 20 mm Hg( r = 0.719 , p < 0.001).
Conclusion: A significant positive correlation exists between IOP measured by GAT and NCT in all IOP ranges.IOP measured by NCT also significantly correlates with CCT. Change in IOP by NCT is 1.21 mm Hg (1.06 to 1.36 mm Hg) per 10 μm change in CCT, and is comparable to that by GAT.
Keywords: Intraocular pressure, Goldmann applanation tonometer, noncontact tonometer, glaucoma.
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