New Technique for Measurement of Ocular Stiffness by Dynamic Analysis in Human

Abstract

Abstract: : Purpose: Corneal stiffness is reported to influence the measurement of intraocular pressure (IOP). The purpose of this study is to develop a new technique for measuring ocular stiffness by dynamic analysis using a high sensitive camera and to examine individual difference in ocular stiffness. Methods: IOP were measured by a non–contact tonometer in 40 healthy subjects and the deformations of cornea by the injected air on the corneal surface were recorded using a high sensitive camera which can take 2,000 photographs per second. Ocular stiffness was calculated by dynamic analysis of corneal deformation. Corneal curvature (CC) and central corneal thickness (CCT) were also measured and their correlations with ocular stiffness were analyzed. Results:Ocular stiffness was 4.56±0.76 N/m (range: 3.39 N/m to 6.40 N/m) and there was a large individual difference between subjects. The CC, CCT and IOP were 7.83±0.24 mm, 536±33 µm and 15.2±2.2mmHg, respectively. The correlations of ocular stiffness with CC (r=0.082, p=0.608), CCT (r= 0.289, p= 0.071) and IOP (r= 0.382, p= 0.020) were weak. Ocular stiffness seemed to be determined not only by CC, CCT and IOP but also by other factors. Conclusions: Ocular stiffness may be determined by multi–factors. There is an individual difference in ocular stiffness, therefore we should pay attention to ocular stiffness in measuring IOP.

Keywords: intraocular pressure