Assessment of total corneal power after myopic corneal refractive surgery in Chinese eyes
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To develop a new regression formula based on the Gaussian thick lens formula and to verify the accuracy of the regression formula.
In this prospective study, 207 eyes of 207 myopic subjects and 133 eyes of 67 postoperative subjects were included. For the 133 postoperative eyes, 127 eyes underwent laser-assisted in situ keratomileusis, and 6 eyes underwent photorefractive keratectomy. Subjective refraction and Pentacam HR were performed preoperatively and postoperatively, and IOLMaster was performed in the postoperative group. SimK, keratometry based on the Gaussian optic formula (KGOF), KCHM obtained using the clinical history method, and the regression formulas KRF1 and KRF2 were calculated.
(1) A statistically significant difference (t = 155.164, P = 0.000) between SimK and KGOF of 1.24 ± 0.12 D was observed, and there was a good correlation between SimK and KGOF (r = 0.996, P = 0.000). The first regression formula (KRF1 = 0.351 + 1.021 × KGOF) was obtained using linear regression. (2) Statistically significant differences (t = 19.114, − 25.184, 4.702, and all P = 0.000) between SimK and KCHM, KGOF and KCHM and KRF1 and KCHM of 0.75 ± 0.45 D, 0.96 ± 0.44 D and 0.18 ± 0.43 D, respectively, were obtained. Good correlations between SimK and KCHM, KGOF and KCHM and KRF1 and KCHM (all r ≧ 0.977, all Ps = 0.000) were also observed. The regression formula (KRF2 = − 1.204 + 1.027 × KRF1) was obtained using linear regression. (3) Six methods were used for the prediction of IOL power in the postoperative group. The highest results were obtained from the Shammas formula (without preoperative data) combining Km (obtained by IOLMaster) followed by the KCHM and KRF2 combining Haigis formula. The third was obtained from the KCHM and KRF2 combining Hoffer Q formula; and the smallest was the Km combining Haigis formula.
The IOL power predicted by KRF2 in eyes after myopic CRS may be accurate.
KeywordsCorneal refractive surgery Corneal power Intraocular lens power Keratometric index Pentacam HR
Yanjun Hua wrote the main manuscript text. Chao Pan collected and analyzed data. Qinmei Wang revised the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare no competing financial interests.
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