Clinical Comparative Study On Laser In Situ Keratomileusis And Sub-bowman’s Keratomileusis For Moderate Myopia Eyes

Objective To comprehensively evaluate the clinical effect of laser in situ keratomil-eusis (LASIK) and sub-Bowman’s keratomileusis（SBK）by investigating the safety,efficacy, predictability and visual quality in eyes with stable moderate myopia undergo-ing these two refractive surgeries.Methods Refractive surgeries were performed on114eyes with stable moderatemyopia:57eyes with LASIK and57eyes with SBK. Spherical equivalent（SE） inLASIK group is-4.45±0.70D, whereas in SBK group is-4.63±0.72D. Visual acuity, spheri-cal equivalent（SE）, contrast sensitivity and higher-order ocular aberrations were re-corded and analyzed preoperatively and1week,1month,3months,6months post-operatively.Results Significant differences were not found in each index between LASIK andSBK at preoperation (P>0.05). At postoperation6months, mean values for uncorrectedvisual acuity (UDVA) of5.0or better was achieved in82.46%of eyes undergoingLASIK and87.72%of eyes undergoing SBK, whereas4.9vision or better was achievedin89.47%and92.98%respectively(P>0.05). Residual spherical equivalent(RSE) be-tween-0.5D and+0.5D was80.70%in LASIK group and85.96%in SBK group,whereas RSE between-1.0D and+1.0D was87.72%and91.23%, respectively (P>0.05).In consideration of contrast sensitivity, significant differences were not found in eachspatial frequency between two treatment groups at preoperation (P>0.05). There wereno statistically significant differences at all time points and spatial frequencies except1.5、3c/d CS in SBK group which was statistically rise more than that in LASIK group at postoperative1month（P<0.05）. No statistically significant differences was found at18c/d CS between any time points in both treatment groups.1.5,3,6,12c/d CS of eyesundergoing LASIK had fell to an statistically significant all time low at postoperative1month.1.5,3,6c/d CS were achieved the preoperative level at postoperative3monthswhile12c/d CS was at postoperation6months.1.5,3,6c/d CS and12c/d CS of eyesundergoing SBK had fell to an statistically significant all time low at postoperative1week and postoperative1month, respectively.1.5,3,6,12c/d CS were all achieved thepreoperative level at postoperative3months. With regarding to higher-order ocular ab-errations, both groups had statistically significant increase on vertical coma-like aberra-tion (C7), horizontal coma-like aberration (C8), spherical-like aberration (C12) and rootmean square higher-order aberrations (Rmsh) at postoperative1week（all P<0.05）. InC7，C8，C12and Rmsh, there were no statistically significant differences at all timepoints except C7in SBK group which was statistically lower than that in LASIK groupat postoperative1month（P<0.05）.C7，C8，C12and Rmsh still did not achieve thepreoperative level at postoperative6months.Conclusion LASIK group and SBK group achieve similar results in safety，efficacy andpredictability. Both treatment groups have statistic significant effects on visual qualityafter surgery. SBK group has better visual quality than LASIK group at early stagepostoperatively. As times goes on, there are no statistic differences on visual qualitybetween two treatment groups.