Comparison of visual results between sub-bowman keratomileusis and conventional thin-flap laser in situ keratomileusis to correct moderate to high myopia

Purpose:To compare the visual results after sub-Bowman keratomileusis(SBK) and conventional thin-flap Laser in Sie Keratomileusis(LASIK) for moderate to high myopia correction.Methods:Patients treated with SBK to correct myopia -3.0 to-9.0 diopters(D) of spherical refractive error and cylinder of 3.0 D or less were compared to age-and refraction-matched patients treated with conventional thin-flap LASIK.The visual results after both procedures were compared at each postoperative visit(one week,one and three months).Results:470 consecutive eyes were included in the study(235 in each group),matched for age and refraction.The mean preoperative spherical refraction value was-6.17±1.67 D in the SBK group(range-3.00 to-9.00 D) and-6.08±1.37 in the LASIK group(range-3.00 to-9.00 D)(P=0.5).The uncorrected visual acuity(UCVA) one week postoperatively was 1.07±0.19 and 1.12±0.17(P0.05),and one month after surgery it was 1.074±0.19 and 1.15+ 0.18,respectively(P=.000).The difference was again statistically significant three month after surgery(1.04±0.20 after SBK,1.15±0.19 after conventional thin-flap LASIK,P=0.001).UCVA was 1.0 in 77.3% of SBK eyes and 94.0% of conventional thin-flap LASIK eyes three months after surgery.At that moment,the efficacy indices were 0.88±0.16 in the SBK group and 0.93±0.19 in the LASIK group(P=0.14).Conclusions:Our results suggest a better visual outcome after conventional thin-flap LASIK compared to SBK but efficacy indices is similar between two groups when correcting moderate to high myopia.