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Laura Tranchina, Marco Lombardo, Francesco Oddone, Sebastiano Serrao, Domenico Schiano Lomoriello, Pietro Ducoli, Marco Centofanti; Comparison Of The Tono-pachymeter NT530P With Goldmann Applanation Tonometer And Influence Of Corneal Properties On Intraocular Pressure Differences Between Tonometers. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5190.
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To analyze repeatability and agreement of the Tono-pachymeter NT530P (Nidek Co., LTD, Gamagori, Japan) with the Goldmann applanation tonometry (GAT), and further estimate the influence of corneal properties on intraocular pressure (IOP) differences between tonometers
Sixty-two normal eyes of 62 subjects were included in the study. Three sessions of measurements, each consisting of three sets of measures, were performed. Repeatability and agreement between tonometers were examined by coefficient of variation (CoV), coefficient of repeatability (CoR) and Bland-Altman analysis. The influence of central corneal thickness (CCT), keratometry (Km), and Ocular Response Analyzer (ORA; Reichert, Buffalo, IL, USA) measurements of corneal viscoelasticity (Corneal Hysteresis, CH; and Corneal Resistance Factor, CRF) on differences between tonometers was further evaluated.
IOP measurements repeatability was higher with the GAT than NT530P: CoV values were 4.3- and 5.5-mmHg and CoR values were 16.6% and 18.4% respectively. The CRF was calculated to be the best predictor of the differences in IOP readings between tonometers (23%; p<0.001), followed by CCT (15%; p=0.003) and CH (14%; p=0.003). Km performed very poorly as lone predictor of IOP differences. In a multiple regression model, CRF, CH and CCT together accounted for 25% (p<0.01) of the variance in IOP reading differences between tonometers
The NT530P demonstrated moderate repeatability in the population studied and should not be used interchangeably with the GAT in clinical practice. Corneal resistance to applanation induced by contact or non-contact tonometers was calculated to be the most determinant factor in influencing differences in IOP values between tonometers.
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