Factors Affecting the Ocular Response Analyzer Parameters in Normal Korean

ABSTRACT

PURPOSE: To identify the normal range of factors which can be measured with Ocular Response Analyzer (ORA, Reichert Inc., Depew, NY, USA) in normal Korean, and to analyze factors affecting ORA by measuring intraocular pressure (IOP) of noncontact tonometer (NCT) and central corneal thickness (CCT). METHODS: Three hundred and one normal Korean subjects who did not have specific ophthalmological diseases and surgeries in the past were recruited for this study. Corneal hysteresis (CH), corneal response factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann correlated IOP (IOPg) were measured using ORA. In addition, IOP of NCT and CCT were measured and the results and factors analyzed. RESULTS: The mean CH measured among normal Korean subjects in this study was 10.70 mmHg. The mean CRF was 10.40 mmHg. CH and CRF were significantly higher in the juvenile group. IOPcc and IOPg as measures of IOP using the ORA had significant correlation with IOP of NCT. In particular, IOPcc appeared to be independent of CCT. CONCLUSIONS: CH and CRF were different according to age, indicating a difference in biomechanical properties of the cornea. In particular, IOPcc is more important as it is independent of corneal thickness and should be compensated in general measurements of IOP reflecting biomechanical properties.