Comparison of Corneal Power Assessment Methods for True Corneal Power After Myopic Small-Incision Lenticule Extraction.

PURPOSE: We sought to compare the accuracy of different corneal curvature parameters in estimating corneal power change in eyes that underwent myopic small-incision lenticule extraction (SMILE).

DESIGN

Prospective cross-sectional trial.

METHODS

89 eyes of 48 patients who had undergone SMILE at Shanghai Eye Disease and Prevention & Treatment Center were enrolled. Total corneal refractive power (TCRP) and total keratometry (TK) values, along with corrected parameters calculated using the Haigis, Shammas, Maloney, and Actual Ka+p methods, were compared with data obtained using the clinical history method (CHM). We also compared the surgically induced changes in TCRP (ΔTCRP) and TK (ΔTK) to changes in the spherical equivalent on the corneal plane (ΔSEco).

RESULTS

After SMILE, differences were smallest between values of TK (0.41 ± 0.48 D) and CHM. The width of the 95% limits of agreement of TK (1.88 D) was narrowest, followed by that of Ka+p (1.94 D). Pearson analysis showed that each parameter had a good correlation with CHM data. The differences between ΔTK and ΔSEco was 0.42 D, when between ΔTCRP and ΔSEco was 0.62 D. The width of the 95% limits of agreement of ΔTK (1.88 D) and the correlation coefficient of ΔTK (0.964) were greater than those of ΔTCRP. A separate case of cataract surgery following SMILE confirmed the validity of the above points in our study (the absolute error was 0.005 D).

CONCLUSIONS

The TK parameter of the IOLMaster 700 can provide accurate and objective corneal power evaluation after SMILE.