Sub-Bowman keratomileusis versus 90 micron thin-flap laser in situ keratomileusis for moderate to high myopia：case-control analysis

李海军   XieLin BaiJi

Ophthalmology department of Daping hospital affiliated with the third military medical university Chongqing China 400042
PURPOSE：To compare the refractive and visual outcomes of sub-Bowman keratomileusis(SBK)and 90 micron thin-flap laser in situ keratomileusis(LASIK)for moderate to high myopia and evaluate the effect of corneal flap thickness on outcomes.

METHODS：Two studies were performed.In the first study，the refractive and visual outcomes in 422 eyes that had SBK and 534 eyes that had 90 micron thin-flap LASIK were retrospectively analyzed.Inclusion criteria were spherical equivalent-3.0 to-11.0 diopters(D)，astigmatism 4.0 D or less，and follow-up 12 months or more.In the second study，the influence of flap thickness was evaluated.A case-control matched study(70 pairs)that controlled for residual stromal bed(RSB)thickness was performed.

RESULTS：The mean flap thickness was 108.1 micron±10.1(SD)in the SBK group and 112.3±12.7 micron in the 90 micron thin-flap LASIK group.There were no significant differences in visual outcomes.In the second study with equivalent RSB thickness，case-control matched comparisons between SBK(mean 108.6±8.0 micron)and 90 micron thin-flap LASIK(mean 119.1±12.5 micron)showed no differences in preoperative and postoperative refractive and visual outcomes.Comparison of the intended versus achieved correction showed no significant differences between the 2 groups.

CONCLUSION：Retrospective analyses showed that the safety，efficacy，and predictability of SBK were similar to those of conventional 90 micron thin-flap LASIK in corneas with equivalent RSB thickness.