ABSTRACT
Background Orthokeratology has been proved to temporarily alter the equivalent sphere,but its effects on visual quality deserve attention.Objective The present study was to investigate the visual quality after overnight orthokeratology in pre-adolescent myopes.Methods Written informed consent was obtained form each subject prior to entering into this series.A descriptive study design was used.One hundred and fifty eyes of 76 teenagers aged (14.90± 1.24)years with low and moderate myopia (-2.79 ± 0.82)D were included in the study.Fitted with Ortho-K contact lens,the lens was wore every night for over 8 hours.Subjective refraction,uncorrected visual acuity (UCVA),contrast sensitivity function,corneal-topography,and aberrometry were examined before,1 week and 3 months after the initiation of orthokeratology.Visual quality was generally evaluated by comparing before wearing,1 week and 3 months after wearing using the National Eye Institute refractive error quality of life instrument (NEI-RQL-42TM).All the procedures were performed by the same clinician.Results Spherical equivalent refractions were (-0.33± 1.02) D and (-0.26 ± 0.60) D 1 week and 3 months after orthokeratology,showing significant decline in comparison with (-2.79±0.82) D of before orthokeratology (P =0.001,0.001).However,no considerable difference was seen between 1 week and 3 months after orthokeratology (P=0.161).Contrast sensitivity function was significantly different in all spatial frequencies before wearing,1 week and 3 months after wearing,and those of 1 week and 3 months after wearing were significantly lower than those of before wearing (1 week:3 cpd P =0.001,6 cpd P=0.001,12 cpd P＜0.05,18 epd P＜0.05 ;3 months:3 cpd P=0.001,6 cpd P=0.001,12 cpd P＜0.05,18 cpd P＜0.05).There was no significant change in contrast sensitivity function between 1 week and 3 months of orthokeratology (P＞0.05).Flat K,steep K and corneal eccentricity (e) were significantly reduced (P =0.000),and surface asymmetry index (SAI) and surface regularity index (SRI) were significantly improved after orthokeratology in comparison with before orthokeratology (both P =0.001).Root mean square (RMS) of total higher-order,third-order and fourth-order aberrations were significantly increased (P＜0.05),but RMS of whole aberration and second-order aberrations significantly decreased after orthokeratology (P＜ 0.05).There were no significant changes in the fifth-order,sixth-order and seventh-order aberration among pre-wear,1 week and 3 months after orthokeratology.Scales of dark to bright,nocturnal driving,glare,visual fluctuate and halo were lower than those before orthokeratology (P＜0.05).The scales of visual fluctuate between 1 month and 3 months after orthokeratology had significant differences (P＜0.01),while the rest of the scales had no significant differences (P＞0.05).Conclusions Orthokeratology can reduce myopic diopter 1 week after orthokeratology.The overnight wearing of fitted orthokeratology can decrease contrast sensitivity and increase corneal surface irregularity and RMS of third-order and fourth-order.Compared with spectacles,orthokeratology reduces subjective visual quality,especially nocturnal quality.