Abstract
Purpose: :
To investigate the agreement in intraocular pressure (IOP) measurement obtained by IOPen rebound tonometry and Goldmann applanation tonometry (GAT) in glaucoma eyes.
Methods: :
cross-sectional study. We selected 152 eyes of 76 glaucomatous subjects, they underwent IOP measurement with IOPen tonometer (MEDICEL) and GAT. The difference between the two values was correlated with central corneal thickness (CCT), keratometry and age. Pearson correlation coefficient was determined to compare IOP readings between IOPen and GAT, regression based Bland-Altmann analisys was used to evaluate agreement between the instruments, multivariate analisys was perfomed to test the influence of K values, CCT and age on the difference between the instruments.
Results: :
Mean IOP measured with IOPen was 15,09 mmHg (range 9-27), and with GAT was 17,22 mmhg (range 8-34). The difference was significant ( p< 0,01)Mean CCT was 548,9 µ, mean keratometry was 43.52 D, mean age was 63.1 years.Mean IOP values obtained by both instruments were significantly correlated (r=0,41 p<0,01), GAT showed a significant correlation with CCT ( r = 0,258 e p = 0,001), but IOPen did not ( r = 0,154, p = 0,057). Neither IOPen nor GAT showed correlation with cheratometry or age. Bland-Altmann analisys revealed a good concordance between the two tonometers.
Conclusions: :
IOPen and GAT showed good correlation and concordance in IOP measurement in glaucoma eyes; IOPen underestimated IOP by 2,13 mmHg compared to GAT. Multivariate analisys did non show any significant influence of the other variables on the difference between IOPen and GAT. We hypothesize that it could depend on other corneal biomechanical properties like corneal hysteresis.
Keywords: intraocular pressure