The influence of pterygium on corneal biomechanical properties

Abstract

Objective The aim of this study is to investigate the influence of pterygium on corneal biomechanical properties by comparing the corneal hysteresis (CH) and the corneal resistance factor (CRF) measured by an ocular response analyzer (ORA) in normal and pterygium eyes.Methods In a case control study,40 patients with monocular nasal simple pterygiums were randomly selected.The contralateral eyes were used for comparison.CH,CRF,IOPg and IOPcc were measured with an ORA and corneal curvature were measured with an corneal curvemeter.A paired t test,linear correlation and regression analysis were used in this study.Results Both the mean CH and CRF in pterygium eyes were both lower than in normal eyes and the differences were statistically significant (t=2.637,2.415,P＜0.05).Both the mean horizontal corneal curvature and vertical curvature in pterygium eyes were lower than in normal eyes and the differences were statistically significant (t=12.447,P＜0.01; t=2.578,P＜0.05).In linear correlation and regression analysis,the D-values of CH and CRF between normal and pterygium eyes were both positively corrclated with that of corneal horizontal curvature (r=0.622,0.678,P＜0.01),and corneal astigmatism (r=0.525,0.515,P＜0.01).Conclusion The CH and CRF were significantly lower in pterygium eyes than in normal eyes,and the D-values of CH and CRF between normal and pterygium eyes were correlated with horizontal corneal curvature.Using the measurements of CH,CRF and corneal curvature is helpful to assess the severity of pterygium's influence on the cornea. Key words: Pterygium ; Cornea; Biomechanical ; Corneal curvature; Corneal astigmatism