Efficacy And Safety Of Orthokeratology Lens Fitted With The Computer-aided Software

ObjectiveDuring the 1-year follow-up period,by analyzing the uncorrected and corrected visual acuity,central corneal curvature,ocular health,corneal endothelial cell count,and axial length before and after wearing the orthokeratology lens（OK）,the myopia control effect of OK,which was fitted by trial fitting and software fitting method,were comprehensively evaluated.Besides,based on the patient’s original corneal topography parameters,the cause of lens decentration（LD）after wearing the OK was analyzed and the corneal morphological parameters were found to predict the lens decentration.Methods1:A total of 100 myopia patients who were fitted with orthokeratology lenses were enrolled and divided into the trial fitting group（50 people）and the software fitting group（50 people）.All the right eyes were selected for further analysis.Before and after wearing the OK,patients need to be performed the uncorrected visual acuity,subjective optometry,corneal topography,and eye health examination.The follow-up visits were baseline,1 day,1 week,1 month,3 months,6 months,and 12 months after wearing the OK.In addition,patients should be evaluated the axial length and corneal endothelial cell counts before and 12 months after wearing the OK,respectively.2:Fifty right eyes of 50 myopes wearing ortho-k lenses were included in the prospective study.Corneal topography was conducted pretreatment to get topographic corneal parameters,including flat-K（K1）;steep-K（K2）;corneal astigmatism（CA）,CA at 0 to 3 mm（3 mm-CA）,3 to 5 mm（5 mm-CA）,5 to 7 mm（7 mm-CA）;surface asymmetry index（SAI）;surface regularity index;the curvature of best-fit sphere;the diameter of cornea（DC）;the distance from the corneal center to the vertex（DCCV）;flat eccentricity（E1）,steep eccentricity（E2）,and E1/E2（E ratio）;and the corneal curvature differences between the nasal and temporal quadrants at 0 to 3 mm(3 mm-K_nt),and the corneal curvature differences between the superior and inferior quadrants at 0 to 3 mm(3 mm-K_si),5 mm-K_nt（at 3–5 mm）,5 mm-K_si（at 3–5 mm）,7 mm-K_nt（at5–7mm）,and 7 mm-K_si（at 5–7 mm）.The relationship between these cornea topographic parameters and LD of the ortho-k was tested using stepwise multiple regression models.Results1:Compared with the baseline,the SER,uncorrected visual acuity,and central corneal curvature altered significantly after OK wear（all P<0.05）.Between the trial fitting group and software fitting group,the parameters were not significant at each follow-up visits（all P>0.05）.Axial length and corneal endothelial cell counts showed insignificant alterations during the one-year period（all P>0.05）.Incidence of corneal staining between the two groups showed indifference during one-year period（P<0.05）.2:The mean magnitude of LD was 0.51±0.23 mm.According to the stepwise analysis,four factors were associated with the overall LD（P<0.01）:SAI（β=0.252）,DCCV（β=0.539）,5 mm-CA（β=-0.268）,and 3 mm-Ksi（β=-0.374）;5 factors were associated with the horizontal LD（P<0.01）:DC（β=0.205）,CCCV（β=0.881）,3 mm-CA（β=-0.217）,5 mm-Knt（β=0.15）,and 3 mm-Ksi（β=-0.18）;and 3 factors were associated with the vertical LD（P<0.01）:SAI（β=0.542）,5 mm-CA（β=-0.188）,and 3mm-Ksi（β=-0.213）.ConclusionsThe OK fitted by the trial fitting method and the software method could effectively control the development of myopia,and there is no difference in the control effect.For specific patients who may need to use more arcs or larger optical areas,the use of software alone may still be limited.Therefore,the combination of the two methods should be used in clinic.Lens decentration is most common,but in most cases,the amount of LD is moderate and acceptable.Besides,the magnitude of LD could be predicted by the corneal morphological parameters.