Consistency study between corneal topography and keratometer during orthokeratology

Objective To evaluate the difference of corneal power and astigmatism axis measured by EyeSys corneal topography and keratometer during orthokeratology.Methods Three hundreds and twenty-one cases underwent orthokeratology performed the examination of corneal topography and keratometer at pre-operation and postoperative 1 day,1 month,the horizontal meridian power magnitude(HK),vertical meridian power magnitude(VK),corneal astigmatism magnitude and its axis measured by two instruments were compared.Results At pre-operation and postoperative 1 day,1 month,HK measured by corneal topography were(43.25±1.16)D,(42.88±1.18)D,(42.79±1.87)D,which were respectively 0.20 D,0.39 D,0.40 D higher than that measured by keratometer,there were significant differences(all P0.01);VK measured by corneal topography were(44.39±1.33)D,(43.96±1.33)D,(43.02±1.64)D,which were respectively 0.13 D,0.32 D and 0.73 D higher than that measured by keratometer,there were significant differences(all P0.01).Astigmatisms measured by corneal topography were 0.06 D,0.10 D and 0.40 D lower than measured by keratometer before and after orthokeratology.The difference of HK,VK,astigmatism and its axis measured by two instruments were greater during treatment(P0.01),and the difference of astigmatism axis had the gradually enlarged tendency.There was no significant difference between two instruments in screening rate of rule astigmatism and non-rule astigmatism(P0.05).Conclusion EyeSys corneal topography as a useful topographic system,can offer complete and accurate information during orthokeratology,so the result of corneal topography should be considered as the main basis,and only taking keratometer as the reference.