Clinical Evaluation of Methods to Correct Intraocular Pressure Measurements by the Goldmann Applanation Tonometer, Ocular Response Analyzer, and Corvis ST Tonometer for the Effects of Corneal Stiffness Parameters

Purpose:

To evaluate the effectiveness of methods to correct intraocular pressure (IOP) measurements obtained using the Goldmann applanation tonometer (GAT), the ocular response analyzer (ORA), and the Corvis ST tonometer (CVS) for the effects of corneal stiffness parameters: central corneal thickness (CCT), corneal curvature (R), and age in a Chinese population.

Patients and Methods:

Data were collected for 99 eyes of 99 participants. Whereas cornea-corrected IOP was obtained directly from ORA (ORA-IOPcc), cornea correction in GAT and CVS was implemented using multiparameter equations developed earlier. The study also included IOP measurements by the dynamic contour tonometer, which is thought to be less affected by corneal stiffness parameters than other tonometers. Statistical analyses were performed to determine the association of both uncorrected and corrected IOP with the main stiffness parameters: CCT, R, and age.

Results:

After correction, a significantly decreased association between the GAT (from r=0.15 to r=−0.02), ORA (from r=0.24 to r=−0.19), and CVS (from r=0.47 to r=0.004) IOP measurements and the CCT was found, to levels below that with the dynamic contour tonometer-IOP (r=0.11). The IOP measurements made by the 4 tonometers, both uncorrected and corrected, did not correlate with age. The same was true for R except with ORA-IOPcc (r=0.23).

Conclusions:

CCT accounted for the majority of variance in IOP, whereas age and R had a much smaller effect. The IOP correction processes studied were successful in reducing reliance of IOP measurements, especially those by GAT and CVS, on CCT in a healthy Chinese population.