Clinical study on the influence of corneal biomechanical properties on early-stage orthokeratology

Objective To investigate the correlation between corneal biomechanical properties and the changes in corneal curvature when undergoing orthokeratology.Methods Fifty-seven eyes of 29 subjects with-1.00--4.75 D of myopia wore overnight reverse-geometry rigid gas-permeable lenses were included in this prospective study.The clinical examination included refractive error,uncorrected and best corrected visual acuity,and slit-lamp examination and were recorded in detail.Corneal resistance factor (CRF) and corneal hysteresis (CH) were measured with an ocular response analyzer.Corneal topography was measured with an Oculus Pentacam analysis system at pre-wear.Keratometric curvature (steep and fiat K values) was measured pre-wear,and 1 day and 7 days post-wear.A one-way ANOVA and correlation analysis were used for statistical analysis.Results The fiat keratornetric curvatures (K1) were significantly reduced from 42.76±0.78 D (baseline) to 41.78±0.86 D after one night of wear,and 40.52±1.26 D after 7 nights of wear (F=71.962,P＜0.01).The steep keratometric curvatures (K2) were significantly reduced from 43.91±0.81 D (baseline) to 43.34±0.89 D after one night of wear,and 42.14±1.44 D after 7 nights of wear (F=40.602,P＜0.01).CRF and CH did not correlate significantly with the reduction of K1 and K2,respectively,after 1 and 7 nights of wear.Conclusion This study indicates that the biomechanical properties CRF and CH did not correlate with the changes in corneal curvature while undergoing orthokeratology. Key words: Biomechanics; Myopia;  Orthokeratology ;  Corneal curvature