Comparison for the Measuring Methods of Intraocular Lens Power to Calculate for Eyes after LASIK

ABSTRACT

Calculating the intraoular lens (IOL)power for an eye that has previously had refractive surgery is a problem because of the difficulty of accurately measuring the corneal power using standard keratometers.To find more accurate method, we compared the accuracy of manual keratometer, calculation and contact lens method for intraocular lens power calculation for eyes after LASIK.The corneal power of 283 eyes were measured using manual keratometer (K (meas))and calculation method (K (calc))involving sphericalequivalent change after LASIK.Mean K (meas) (38.27 diopters[ D] )was significantly greater than mean K (calc) (36.64 D).Corneal power overestimation by manual keratometry correlated significantly with the spherical equivalent change after LASIK.The corneal power of 76 eyes were measured using hard contact lens method (K (rgp))in addition to above two methods.Mean K (meas) (38.53 D)was significantly greater than mean K (rgp) (37.78 D), which was significantly greater than mean K (calc) (36.91 D).The difference between K (meas)and K (rgp) did not correlate with the spherical equivalent change after LASIK.According to this study, if there is largely changed refraction after LASIK, it would be more ideal to use the calculation method.In case of small change after LASIK or PRK, it would be more recommendable to select lower one after comparing two values which come from calculation method and contact lens method.Even though we have theoretical conclusion to avoid error which induces hyperopia, it should be testified through clinical apply.