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Subject Area

Internal Medicine

Article Type

Original Study

Abstract

Objectives To compare intraocular pressure (IOP) readings measured by the ocular response analyzer (ORA) with those measured by the Goldmann applanation tonometer (GAT) following penetrating keratoplasty (PKP) and evaluate the influence of biomechanical properties of the grafts on IOP measurements. Background The ORA (Reichert Technologies) is a device that shows the biomechanical properties of the cornea. It reflects certain biomechanical properties of the cornea such as corneal hysteresis (CH) and corneal resistance factor (CRF). Patients and methods IOP using the GAT [IOP (GAT)], CH, CRF, Goldmann-correlated IOP (IOPg), cornea-compensated IOP (IOPcc) using the ORA, and central graft thickness (CGT) were measured in 30 eyes undergoing PKP. Bland–Altman plots were used to evaluate agreement between the tonometers. The correlation between refraction, graft curvature, astigmatism, CH, CRF, and CGT with IOP readings was investigated using multivariate regression analysis. Results The mean CGT, CH, and CRF were 532.43 ± 30 μm, 8.52 ± 1.81 mmHg, and 8.56 ± 1.59 mmHg, respectively. Mean IOP (GAT), IOPg, and IOPcc were 11.88 ± 3.66, 14.64 ± 4.08, and 17.27 ± 4.60 mmHg, respectively. The 95% limit of agreement between IOP (GAT) and IOPg ranged from 2.39 to 3.29 mmHg, and for IOPcc and IOP (GAT) it ranged from 4.7 to 6.2 mmHg. No significant association was found between CGT and IOP readings. According to IOP (GAT), there was significant negative association with CH. According to IOPcc, there was significant negative association with CH and mean keratometry. According to IOPg, there was significant positive association with CRF. Conclusion Following PKP, graft biomechanics had more influence on IOP values than anatomical features. In comparison to the GAT, the ORA yielded higher IOP values.

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