Intraocular Lens Power Calculation In Myopia After Corneal Refractive Surgery

[Objective]: to evaluate the accuracy of several ways to predict IOL power in myopia after SMILE surgery and provide Clinical evidence.[Methods]:a prospective comparison study.141 cases (268 eyes) are divided into A (axial length <26mm) group (n=160) and B (axial length≥26mm) group(n=108), corneal curvature of all eyes are measured preoperatively by phoropter, corneal topography and IOL-Master, corneal curvature, anterior chamber depth and axial length of eyes are measured by IOL-Master before and after operation.. SMILE are performed in both groups, power, postoperative corneal curvature which estimated by clinical history methodes substituted in SRK/T, Holladay I, Hoffer Q, haigis and Double-KSRK/T formula, corneal bypass method and Haigis-L formula are also used to calculate the IOL power. Paired t test and variance analysis are performed with SPSS20.0.[Results]:there is no significant difference(P>0.05)among the preoperative corneal curvature obtained by phoropter, corneal topography and IOL-Master; the differences between preoperative and postoperative anterior chamber depth,axial length and corneal curvature are all significant (P< 0.05); corneal curvature obtained by clinical history method (CHM) and IOL-Master are significantly different(P<0.05); when 23.07mm≤AL<26mm, IOL power Haigis-L> Corneal bypass> D-KSRK/T> CHMHaigis> CHHoffer Q> CHM Holladay I> CHMSRK/T, Haigis-L method is significantly different with others(P< 0.05), but there is no significant difference among corneal bypass, D-KSRK/T andCHMhaigis(P>0.05).28.93mm≥AL≥26mm, Haigis-L> CHMhaigis>D-KSRK/T> CHMHofferQ> cornealbypass> CHMHolladayI> CHMSRK/T, Haigis-L method is significantly different with others(P<0.05), there is no significant difference between CHMhaigis and D-KSRK/T(P<0.05), also between corneal bypass and D-KSRK/T.[Conclusions]:①high consistency and accuracy of corneal curvature measured by ph oropter, corneal topography and IOL-Master in normal eye, the resultscan be replaced for each other; ②postoptative corneal curvature, anterior chamber and axial length are smaller than preoperative ones, it should be considered When calculating the IOL po wer after refractive surgery; ③postoperative corneal curvature estimated with clinical h istory method and measured by IOL-Master are not consistent, the latter is larger, th ey can not be substituted for each other; ④CHMhaigis, corneal bypass method, and D-K SRK/T with high accuracyin the presence of preoperative and postoperative data; on the condition of complete lack of preoperative data, to choose Haigis-L formula, and to re ducel.OD of Haigis-L value as the pre-implantation IOL power.