AIM: To evaluate the accuracy of the Barrett True K intraocular lens(IOL)calculation formulas in eyes with previous radial keratotomy(RK).

METHODS: From February 2017 to February 2019, 42 eyes of 22 cataract patients with previous RK were selected in our hospital. Two methods were used to calculate IOL refraction before surgery: 1)Selected the smallest anterior surface K value in the area of 3mm central corneal diameter, used SRK/T formula, the target refraction was set at -1.0D; 2)Used Barrett True K on-line calculation formula, the mode of RK was selected and the target refraction was set at -1.0D. Three months after operation, the refractive state of the eyes was examined and the refractive errors calculated by the two methods were compared.

RESULTS: The average refractive error of Barrett formula method was 0.61(-0.37, 0.88)3mo after operation, which was significantly lower than that of traditional formula method 0.35(-0.25, 0.63)D(P<0.05). There was no significant difference in absolute refractive error between the two methods(P>0.05). The refractive errors of traditional formula method in the range of ±0.5D, ±1.0D, ±2.0D accounted for 21%, 45%, 90% respectively. The refractive errors of Barrett formula method in the range of ±0.5D, ±1.0D, ±2.0D accounted for 31%, 74%, 100% respectively(P<0.05).

CONCLUSION: Barrett True K online formula applied to cataract patients after RK can achieve satisfactory refractive status.