Influence of corneal biomechanical properties on intraocular pressure differences between an air-puff tonometer and the goldmann applanation tonometer

Purpose: To estimate the influence of corneal properties on intraocular pressure (IOP) differences between an air-puff tonometer (NT530P; Nidek) and the Goldmann applanation tonometer (Haag-Streit). Patients and Methods: The influence of central corneal thickness (CCT), keratometry, and Ocular Response Analyzer (Reichert) measurements of corneal viscoelasticity [corneal hysteresis (CH) and corneal resistance factor (CRF)] on IOP differences between tonometers was evaluated. Results: The CRF was calculated to be the best predictor of the differences in IOP readings between tonometers (r²=0.23; P<0.001), followed by CCT (r²=0.15; P=0.003) and CH (r ²=0.14; P=0.003). Keratometry performed very poorly as lone predictor of IOP differences. In a multiple regression model, CRF, CH, and CCT together accounted for 25% (r²=0.25; P