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Stability of the Barrett True-K formula for intraocular lens power calculation after SMILE in Chinese myopic eyes

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First Author: Z.Wei CHINA

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Abstract Details

Purpose:

To compare the Barrett True-K Formula with other formulas integrated in Lenstar 900 to predict intraocular lens (IOL) power after small-incision lenticule extraction (SMILE).

Setting:

To compare the Barrett True-K Formula with other formulas integrated in Lenstar 900 to predict intraocular lens (IOL) power after small-incision lenticule extraction (SMILE).

Methods:

A theoretical prospective study was performed to predict the ratio of equivalent IOL power before and after SMILE using the SRK/T, Holladay 1, Haigis, and Barrett True-K formulas and compare the stability of their predictions. The study included 54 eyes (54 cases) with a manifest refraction spherical equivalent of –4.99±1.45D. All subjects enrolled in this study were examined with the Lenstar 900 before and 6 months after SMILE including measurements of axial length, corneal curvature, and anterior chamber depth. Significant differences were analyzed with SPSS 25.0 software.

Results:

The prediction of equivalent IOL power of the two groups was more stable for the Barrett True-K formula, especially in long axial-length eyes (group B). The respective percentages for the SRK/T, Holladay 1, Haigis, and Barrett True-K formulas were 7.4%, 7.4%, 85.19%, and 88.89% for a margin of error within 0.5D; 25.92%, 51.84%, 100%, and 100% for a margin of error within 1.0D in group A; 33.33%, 40.74%, 44.44%, and 81.48% for a margin of error within 0.5D; and 44.44%, 59.26%, 66.66%, and 92.59% for a margin of error within 1.0D in group B.

Conclusions:

Theoretically, the Barrett True-K formula provides more stable predictions than other formulas for cataract eyes after SMILE. However, this finding should be confirmed by further studies.

Financial Disclosure:

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