ABSTRACT
· AIM:To investigate the effects of mitomycin C (MMC) on corneal endothelial cells at different exposure time during laser-assisted subepithelial keratomileusis (LASEK).· METHODS:Patients who received LASEK were included and divided into Group T1 (15s≤t≤45s) and T2 (5s＜t≤70s) based on the exposure time of MMC with corneal stroma.Cell density (CD) of corneal endothelial cells in central and peripheral cornea,average cell area (ACA),area standard deviation (SD),coefficient of variation (CV) and percentage of hexagonal cells (HEX) before surgery and at 1wk,1,3 and 6mo after surgery were compared between and within the groups.· RESULTS:A total of 196 eyes of 98 patients were included with 98 eyes in Group T1 and 98 eyes in Group T2.With the exception of peripheral ACA,central CV and HEX in Group T1 and T2,which significantly changed at 1wk after the surgery (P＜0.05),there was no significant difference in central and peripheral parameters within both groups or between the groups (P ＞0.05).· CONCLUSION:Although transient acute changes in central CV and HEX and peripheral ACA were observed,there is no significant effect on the long-term corneal health status when MMC is applied in a reasonable time range in LASEK surgery.
ABSTRACT
@#AIM: To compare the difference of biomechanical stability after a femtosecond laser-assisted <i>in situ</i> keratomileusis(FS-LASIK)and laser-assisted subepithelial keratomileusis(LASEK)by ocular response analyzer(ORA). <p>METHODS: This prospective study was conducted at the First Affiliated Hospital of Harbin Medical University, and myopic patients with the equivalent sphere between -2.00 and -5.00 diopters from January 2016 and December 2017 were enrolled. All the subjects were divided into FS-LASIK and LASEK group respectively according to different surgical methods. There were 64 patients(100 eyes)participated in the FS-LASIK group while 53 patients(100 eyes)in the LASEK surgery group. Corneal hysteresis value(CH)and corneal resistance factor value(CRF)were measured pre-, 1mo and 3mo postoperation of all the subjects. And the variance analysis of two groups was repeated to compare the overall difference between the two modes of operation from pre-operation to post operation. <p>RESULTS: The CH and CRF value of the two groups were different before and after operation(<i>P</i><0.05). The comparison results of repeated measurements showed that the CH value and CRF value of the surgical methods were reduced in 1 and 3mo after operation, respectively, and there was significance(<i>P</i><0.05). The CH and CRF of FS-LASIK group was lower than LASEK group only in 1mo after the operation(<i>P</i><0.05). <p>CONCLUSION: Both surgeries could affect the biomechanical stability of cornea. From the point of view of biomechanical stability, LASEK operation is safer than FS-LASIK operation and reduces the possibility of postoperative refractive regression.