AIM:To assess the visual outcomes and corneal biomechanical properties of myopia patients between laser in situ keratomileusis(LASIK)and LASIK combined with accelerated corneal crosslinking(LASIK Xtra).METHODS:This prospective study analyzed 52 consecutive myopia patients treated with LASIK Xtra and 45 consecutive myopia patients treated with LASIK.Only the right eyes in the two groups were analyzed.The uncorrected distance visual acuity(UDVA),keratometry values,postoperative central corneal thickness(CCT),corneal demarcation line depth,the corneal compensated intraocular pressure(IOPcc),Goldmann-correlated IOP(IOPg),corneal resistance factor(CRF)and corneal hysteresis(CH)from Ocular Response Analyzer(ORA)were analyzed.Further,the correlation between the demarcation line depth and ORA-related biomechanical parameters were analyzed.RESULTS:No significant differences in UDVA,postoperative CCT,or mean K values were found between the 2 groups at 1 to 12mo postoperative follow-up(all P>0.05).The changes of CRF was significantly lower in the LASIK Xtra group compared to the LASIK group(all P<0.05)at all the postoperative visits.The changes of CH were significantly higher in the LASIK Xtra group(all P<0.05).No significant differences were discovered regarding the changes of IOPcc and IOPg posperatively(all P>0.05).Out of 52 cases in the LASIK Xtra group,the demarcation line was present in 40 eyes(77%).The average depth of the demarcation was 220.73±42.70μm(136 to 288μm).No significant correlation was observed between the depth of the demarcation line and any of the ORA-related biomechanical parameters such as IOPcc,IOPg,CRF and CH at 12mo(all P>0.05).CONCLUSION:Both procedures demonstrate comparable outcomes in terms of visual acuity,refraction and ablation predictability.This study confirms that corneal biomechanical properties of the included patients weakened after both procedures,but the cornea after LASIK Xtra are stiffer than conventional LASIK.
Li ZhangYue-Hua ZhouXiao-Rui WangYan ZhengCai-Yun FuXiu-Mei SongYa-Bin HuYue WangChang-Bin Zhai
AIM:To investigate changes in local brain activity after laser assisted in situ keratomileusis(LASIK)in myopia patients,and further explore whether post-LASIK(POL)patients and healthy controls(HCs)can be distinguished by differences in dynamic amplitude of low-frequency fluctuations(dALFF)in specific brain regions.METHODS:The resting-state functional magnetic resonance imaging(rs-fMRI)data were collected from 15 myopic patients who underwent LASIK and 15 matched healthy controls.This method was selected to calculate the corresponding dALFF values of each participant,to compare dALFF between the groups and to determine whether dALFF distinguishes reliably between myopic patients after LASIK and HCs using the linear support vector machine(SVM)permutation test(5000 repetitions).RESULTS:dALFF was lower in POL than in HCs at the right precentral gyrus and right insula.Classification accuracy of the SVM was 89.1%(P<0.001).CONCLUSION:The activity of spontaneous neurons in the right precentral gyrus and right insula of myopic patients change significantly after LASIK.SVM can correctly classify POL patients and HCs based on dALFF differences.
