The Effects of Corneal Edema on the Intraocular Pressure Measurements

INTRODUCTION: To evaluate the possible effects of corneal edema on intraocular pressure (IOP) measurements obtained with three different tonometers on the first day after cataract surgery.
METHODS: Sixty-four eyes of the 64 patients underwent phacoemulsification and IOP measurements using Goldmann applanation tonometer (GAT), Tono-Pen applanation tonometer (TAT), and Pascal digital contour tonometer (DCT) the first day after surgery. Central corneal thickness (CCT) measurements were used to quantify the postoperative corneal edema. Intraclass correlation coefficient and Bland-Altman plot were used to assess the compatibility of IOP measurements among three method pairs.
RESULTS: TAT and DCT IOP measurements were found to be compatible with each other (p=0.141) in the corneal edema group. The GAT and TAT IOP measurements in the eyes with corneal edema were inversely proportional to the CCT values (p=0.011 and p=0.033, respectively), but the DCT relationship was not statistically significant (p=0.44).
DISCUSSION AND CONCLUSION: The lack of a significant relationship between DCT and CCT in edematous corneas may suggest that DCT, as in normal corneas, can perform CCT-independent measurements. However, there is still no gold standard method for IOP measurement in edematous corneas.