Agreement of intraocular pressure measured by noncontact tonometer and Goldmann applanation tonometer: a Meta-analysis

Abstract

Background Noncontact tonometer (NCT) is a common application in clinical ophthalmology, while its measured value is influenced by corneal parameter.In recent years, there existed some clinical trials discussing the agreement between NCT and gold standard Goldmann applanation tonometer (GAT), but there was still lack of evidence. Objective This study was to evaluate the agreement between NCT and GAT by applying evidence based medicine (EBM) method. Methods A systematic literature retrieval was conducted from the MEDLINE, EMbase, CBM disc and CNKI database with the limitation of publishing time until June 2016.The literatures were screened according to the inclusion and exclusion criteria.The sample size, average age, sample characteristics and follow-up time were extracted.The value of intraocular pressure measured by NCT and GAT were analyzed.The overall effect size was analyzed using Review Manager 5.3 (from The Cochrane Collaboration) as weighted mean difference (WMD). There existed heterology in this study.Radom effect mode was used to evaluate and compare the difference between NCT and GAT value. Results Twenty four articles were retrieved.Six comparison studies incorporated with 478 eyes were included for Meta analysis.After random effects model was performed for correction.Intraocular pressure measured by NCT was 0.02 mmHg larger than that by GAT (1 mmHg= 0.133 kPa). There was no significant difference in the measurement value of IOP between the two instruments (WMD=0.02, 95%CI: -0.59 to 0.63, P=0.95). Funnel chart method showed that literature publication bias existed in this study. Conclusions Normal persons' IOP obtained from NCT and GAT showed a good reproducibility.More comparison studies are needed to support this result. Key words: Intraocular pressure; Non-contact tonometer; Goldmann applanation tonometer; Meta-analysis; Evidence-based medicine