A comparison of goldmann applanation tonometry and rebound tonometry measurements among patients attending a glaucoma clinic in Southwest Nigeria

Abstract

Background: The accurate measurement of intraocular pressure (IOP) is a fundamental basic examination in daily ophthalmic practice and is important in managing many ophthalmic diseases and conditions such as glaucoma, uveitis, and following trauma. Accurate measurement of IOP is particularly important in glaucoma because the intraocular pressure is the most important modifiable risk factor in its management. Aim: To compare intraocular pressure (IOP) measurements obtained with the Goldmann applanation (GAT) tonometer to intraocular pressure measurements obtained with the iCare rebound tonometer (RBT) and evaluate the suitability of the iCare tonometer for routine clinical use among adult patients attending a glaucoma clinic in Southwest, Nigeria. Patients and Methods: The study was a comparative cross-sectional study. A total of 132 eyes of 132 patients were recruited for the study. Three consecutive IOP measurements were obtained with each of the instruments by the same observer. A difference in IOP of ± 3 mmHg between the two instruments was considered clinically significant in this study. Results: The mean IOP measurement from GAT was 15.18 mmHg (±4.26 mmHg) and 16.32 mmHg (±4.48 mmHg) from RBT. The mean central cornea thickness was 520.66 μm (±33.34). Pearson's correlation (r = 0.84) revealed a strong statistically significant correlation between GAT and RBT measurements and paired student t-test revealed a statistically significant difference in the means of IOP obtained by the GAT and RBT. There was a tendency for RBT to yield higher IOP measurements. Conclusion: The intraocular pressure measurements obtained with iCare RBT and GAT though strongly correlated, showed statistically significant differences in the means. The impact of central cornea thickness on measurements obtained by GAT and RBT was statistically insignificant. The iCare rebound tonometer, cannot replace GAT for routine use in the glaucoma clinic.