Comparison of intra-ocular pressure measurement with four different methods of tonometry

Abstract

The aim of this study was to measure the intraocular pressure (IOP) by Perkins hand held tonometer, non contact tonometer(NCT) and rebound tonometer with the Gold standard GAT and to analyse their correlation with varied CCT. Cross-sectional, hospital- based study that included 200 patients from the glaucoma department. After complete eye evaluation, the IOP measurement was performed sequentially in the same order- NCT, RT, Perkin’s and GAT. CCT was then measured for all the patients. The intra-ocular pressure within the eyes was compared by paired “t” test and between the right and left eyes were compared by the independent “t” test. Mean age of the patients was 54.5±13.5 years. The mean IOP of Right and Left eyes measured with GAT were 15.9±6.2 and 16.3±7.0 mm/Hg, that with Perkins were 15.7±6.2 and 16.3±7.0 mm/Hg respectively. Both eyes’ mean IOP were 15.4±6.7 and 15.9±7.4 mm/Hg by Icare. The mean IOP measured by NCT were 16.4±6.7 and 16.9±8.0 mm/Hg. The mean CCT of right eye was 528.9± 29.6 and left eye was 530.6±29.6 microns. All the four instruments namely GAT, Perkin’s, Icare ic100 and NCT were influenced by CCT. IOP remains the only alterable factor in the management of glaucoma patients. Numerous methods have been devised to measure IOP accurately. The IOP measured with Perkin’s, NCT and Icare are comparable but GAT remains the gold standard.