Abstract
Purpose:
Chinese have high prevalence of myopia than other ethnic groups. Lower corneal hysteresis was reported in Chinese with longer axial length. This study compared corneal biomechanical properties in healthy Chinese, Indian and Caucasian.
Methods:
One hundred and forty-eight normal subjects (age range from 9-31 years old) were enrolled in this study (Chinese= 93, Indian= 27, Caucasian= 28). Corneal hysteresis (CH) and corneal resistance factor (CRF) were obtained using the Ocular Response Analyzer. Axial length (AL) was measured using optical biometry while central corneal thickness (CCT) was obtained using non-contact specular microscopy. Due to the limitation of the settings, AL was measured in 97 subjects while CCT was only measured in 51 subjects. Both eyes of each subject were used for analysis. The associations between CH and CRF with age, gender, AL, corneal curvature and CCT were evaluated.
Results:
All ethnic groups had similar corneal curvature and CCT (p> 0.05). Chinese subjects had significantly longer AL (24.05±1.11mm) compared with Indian subjects (23.59±0.94mm) and Caucasian subjects (23.47±0.66mm). Indian subjects had significantly higher CH (11.81±1.33mmHg) than Chinese subjects (11.25±1.37mmHg) and Caucasian subjects (11.34±1.76mmHg). Indian subjects also had significantly higher CRF (11.86±1.87mmHg) than Chinese (11.15±1.48mmHg) and Caucasian subjects (10.71±1.87mmHg). Age had negative association with CH and CRF (p< 0.0001). CH and CRF were significantly higher in female than in male (p< 0.0001). There was significantly negative association between AL and CH (p= 0.001), but no significant association was found between AL and CRF (p> 0.05). CH and CRF were significantly increased with CCT (p< 0.0001). After adjusting for age, gender, CCT, AL and corneal curvature, there were still significant ethnical difference in CH (p< 0.05) and CRF (p< 0.01).
Conclusions:
Different corneal biomechanical properties were found in Chinese, Indian and Caucasian. A longitudinal study is needed to determine the role of CH in the axial elongation.
Keywords: 479 cornea: clinical science •
605 myopia