Ocular Response Analyzer versus Goldmann Applanation Tonometer for Measurement of Intra-Ocular Pressure

Abstract

Abstract Background Goldmann applanation tonometry (GAT) has been the gold standard for intraocular pressure(IOP) measurement ,since its appearance in clinical practice around 50 years ago.(1) In spite of being almost unchallenged, the last few years have become a sustained search for a new standard method for IOP measurement,. One such recently marketed instrument is the Ocular Response Analyzer (ORA), which able to detect the corneal biomechanics. Aim of the Work is to compare the IOP measurement estimated by Goldmann applanation tonometer to that of ORA and detect the effect of state of refraction, corneal topography and central corneal thickness (CCT) on these measurements. Patients and Methods This cross-sectional study was done from March 2018 to October 2018 on 65 eyes of patients visiting the outpatient clinic. Results The mean GAT IOP was 15.938 ± 6.041 while the mean ORA (IOPcc) and (IOPg) were 19.711 ± 7.59 and 17.242 ± 7.35 mm Hg respectively. There is a strong positive relationship between GAT IOP & ORA IOPg measurement (r = 0.880 – p = <0.001*). Also finding a weak yet significant correlation between IOPg and CCT (r = 0.385, p = 0.001). None of the pressure measurements was affected by refraction or corneal curvature significantly. Conclusion In conclusion, our results suggest that mean IOPs obtained by ORA were significantly higher than that of GAT with different influencing factors that are not completely understood. caution has to be sought when using the ORA, the values obtained ought not to be used interchangeably with the values obtained by 1 GAT, despite the presence of a positive correlation between these values. This underlines the importance of using one and only method of evaluation of the IOP for every patient in successive follow-up visits.