Clinical Optometry (Oct 2019)
Biomechanically-Corrected Intraocular Pressure Compared To Pressure Measured With Commonly Used Tonometers In Normal Subjects
Abstract
Mohammad-Reza Sedaghat,1 Hamed Momeni-Moghaddam,2,3 AbbasAli Yekta,3–5 Ahmed Elsheikh,6–8 Mehdi Khabazkhoob,5,9 Renato Ambrósio Jr,10 Nasim Maddah,3 Zeynab Danesh3 1Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; 2Health Promotion Research Center, Zahedan University of Medical Sciences, Zahedan, Iran; 3Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran; 4Refractive Errors Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; 5Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran; 6School of Engineering, University of Liverpool, Liverpool, UK; 7School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China; 8NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK; 9Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 10Federal University of the State of Rio de Janeiro, Rio de Janeiro, BrazilCorrespondence: Hamed Momeni-MoghaddamDepartment of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Parastar 2 Str., Ahmadabad Blvd., Mashhad 9189754151, IranTel +98 511 9155337952Email [email protected]: To compare the biomechanically-corrected intraocular pressure (bIOP) measured by the Corvis ST (Oculus, Wetzlar, Germany) with IOP measurements made by other commonly used tonometers; and to test the correlations between IOP measures and central corneal thickness.Methods: One randomly-selected eye from each of 94 healthy subjects was assessed. The bIOP was determined by the CorVis ST and compared with the IOP measurements made by standard Goldmann Applanation Tonometer (GAT: Haag-Streit AG, Bern, Switzerland), the Icare (Icare Finland Oy, Vantaa, Finland), and the Ocular Response Analyzer (ORA-IOPcc: Reichert, New York, USA). Corneal thickness was assessed by the Oculus Pentacam. The correlation between bIOP and the other devices and between CCT were assessed using the Pearson correlation test or Spearman’s rho test accordingly to the distribution of these values. The Bland-Altman method and intraclass correlation coefficients (ICC) were used to assess the agreement of bIOP results with IOP obtained with other techniques. The limits of agreement (LoA) were determined as the mean difference ±1.96 SD of the mean differences. In all tests, the significance level was considered to be 0.05.Results: Mean and SD of the bIOP were 16.11±1.66 mmHg. Significant differences were found between the bIOP and other IOP measurements (GAT, 3.02±2.60 mmHg, p<0.001, Icare, 1.51±2.95 mmHg, p<0.001, IOPcc, 1.09±1.96 mmHg, p<0.001). The lowest and highest mean differences in IOP were with the IOPcc and GAT, respectively. Interestingly, there were no significant differences in bIOP, GAT-IOP and ORA-IOPcc between the eyes with thin or thick corneal thicknesses, with Icare-IOP being the only exception (p<0.001).Conclusion: The Corvis bIOP has a higher correlation with the IOPcc by ORA, which are also compensated for the effects of corneal biomechanics and have less association with corneal thickness relative to the uncorrected GAT and Icare measurements.Keywords: tonometry, intraocular pressure, corneal biomechanics
