正常角膜及圆锥角膜的生物力学特性比较研究

Objective To compare the corneal hysteresis (CH) and corneal resistance factor (CRF) measured with the Ocular Response Analyzer (ORA) in normal and keratoconic eyes. Methods It was a case-control study. Random selected 96 normal eyes and 46 keratoconic eyes in the same period were included in this study. Normal eyes were divided into 2 groups: high corneal astigmatism (≥3.00 D) and low-to-moderate corneal astigmatism (<3.00 D). Keratoconic eyes were also divided into 3 groups based on Amsler-Krumeich classification: mild (stage Ⅰ), moderate (stage Ⅱ) and severe (stage Ⅲ/Ⅳ). CH and CRF were compared between groups and the areas under ROC curves of the CH and CRF were calculated. Results The mean CH and CRF were (7.1±1.6) mm Hg and (6.3±1.5) mm Hg in keratoconic eyes compared with (10.1±1.3) mm Hg and (10.5±1.6) mm Hg in normal eyes. The difference were statistically significant(t=-11.813, -14.943 ;P<0.001). In normal eyes, there was no difference of CH or CRF between the high corneal astigmatism and low-to- moderate corneal astigmatism (t=0.373,0.095; P>0.05). In keratoconic eyes, there was a significant negative correlation between CH and the keratoconus grade (r=-0.627, P<0.001) and the same relationship was found between CRF and the keratoconus grade (r=-0.587, P<0.001). In multiple linear regression analysis, CH was correlated with central corneal thickness (CCT) and corneal curvature (r=0.320, -0.375;P<0.05) and CRF was correlated with corneal curvature in keratoconic eyes (r=-0.441 ,P<0.01), while they were only correlated with CCT in normal eyes (r=0.367,0.459;P<0.001). The areas under ROC curves of the CH and CRF were 0.9282 and 0.9731 (Z=20.462,38.305 ;P<0.0001), the difference between them was significant (Z =7.134,P=0.008). Conclusions The CH and CRF were significantly lower in keratoconic eyes than in normal eyes, especially on CRF. The long-term follow-up of CH and CRF may provide information for evaluation of progression of keratoconus. They may be included as indicators for detecting keratoconus.

A compare study on cornea biomechanical properties in normal and keratoconic eyes