| Objective To investigate the changes of corneal optical density in patients with keratoconus with conventional corneal cross-linking(CXL)before and after operation,and to compare with the simple removal of epithelial excimer laser subepithelial keratomileusis.(Laser Assisted Subepithelial Keratomileusis,LASEK)before and after surgery to investigate whether depilation had an effect on corneal optical density after conventional epithelial corneal cross-linking.MethodThe first is an observational study.10 eyes of 10 patients with keratoconus and 16 eyes of 16 patients with LASEK surgery were selected and divided into 2 groups according to different surgical procedures.The pentacam three-dimensional anterior segment analysis and diagnosis system(Oculus,Germany)was used for examination.Two sets of data were analyzed.The t-test was performed to observe the difference in optical density between the keratoconus patient's cornea and the normal human cornea;the latter two groups were separately CXL surgery and LASEK surgery were performed with the corneal center 6 mm.After wearing soft contact lenses for 3 days,Coptiflux(0.1% levofloxacin)was given for 1 week and 0.1% fluorometholone for 3 months.The patients were followed up at 1 month and 3 months after surgery,and were also examined with the pentacam three-dimensional anterior segment analysis and diagnosis system(Oculus,Germany).Preoperative and postoperative differences were analyzed using a paired-sample t-test.Between the two groups,repeated measures analysis of variance was performed to analyze the effect of different surgical procedures and the optical density over time.And calculate the average value of each group in each inspection of different areas.Result1.In the basic data description,the basic data of the CXL group were preoperative corneal 120?m(?0~2mm): 24.17±2.65,and the first corneal 120?m(?0~2): 31.87±3.47.The corneal anterior 120?m(?0~2)was 31.50±3.63 3 months after operation;120?m(?2-6): 20.55±1.58 preoperatively;120?m(?2-6): 25.62±2.34 one month before surgery;After the first 3 months,120 ?m(?2~6): 24.58±1.67;before the operation,120 ?m(full layer): 22.24±2.30;120 ?m before the first postoperative period(full layer): 25.38±2.97.2.Paired-sample t-test of CXL group showed that the center of the front 120?m layer of the cornea is 0~2mm,the center of the front 120?m is 2~6mm,the whole area of the front 120?m,the center of the center layer is 0~2mm,and the center of the center layer is 2~6mm.The optical densities of the entire layer of the central layer,the center of the whole layer 0~2mm,the center of the full layer 2~6mm,and the whole cornea after 1 month and 3 months were all significant compared with preoperative(P<0.05).,while the rest of the area is meaningless.3.The paired sample t-test of the LASEK group showed that the center of the front 120 ?m layer of the cornea was 0 to 2 mm,the area of the front 120 ?m to 2 to 6 mm,the entire area of the front 120 ?m,the center of the center layer of 0 to 2 mm,the entire layer of the central layer,and the entire layer.The optical densities in the central 0~2mm region,the central 2~6mm region of the full layer,and the whole cornea at 1 month and 3 months after operation were all significant compared with the preoperative ones(P<0.05),while the other regions had no significance.4.The analysis of variance of the two groups of data in the design of the two groups showed that,in the case of full-thickness cornea,there was no statistical difference between different surgical procedures,and there was no significant difference at different time points.From the other regions,There was a statistically significant difference at different time points(P<0.05).At the same time,the interaction between time and different surgical methods was statistically significant,and there was statistical significance between different surgical procedures.Conclusion 1.The corneal optical density will increase after CXL,but the corneal optical density will decrease after LASEK.2.After CXL,corneal 120?m layer center 0~2mm area,120?m center 2~6mm area,front 120?m full layer,center layer center 0~2mm area,center layer center 2~6mm area,central layer full layer The optical densities of the whole cornea at the center of the 0 to 2mm region in the entire layer,the 2 to 6mm region at the center of the full layer,and the total cornea were increased at 1 month and 3 months after operation,and were significant.Prove that the role of CXL itself will lead to increased corneal optical density.3.After LASEK,corneal 120?m layer center 0~2mm area,120?m center 2~6mm area,front 120?m full layer,center layer center 0~2mm area,central layer full layer,full layer center 0~2mm area The optical densities at 1 month,3 months,and 1 month after surgery in the central 2-to 6-mm area of the full-thickness layer and in the whole cornea were reduced compared with those before surgery and were significant.It is proved that the simple removal of the epithelium does not lead to an increase in corneal optical density,but it also leads to a decrease in corneal optical density.After reading the data,this phenomenon cannot be explained for the time being.4.After comparing the two groups,it was concluded that the greater increase in optical density after CXL may be due to the change of collagen fibers in the corneal stroma caused by the cross-linking reaction or the cross-linking reaction between fibroblasts.Caused by qualitative edema.5,due to the incidence of keratoconus,the study involved a small number of cases,follow-up time is short,there is room for improvement in this regard.And this study does not rule out the possibility of cross-linking surgery may cause damage to the corneal endothelium,it is necessary to continue to rule out these factors.LASEK was performed in the control group.Since LASEK surgery itself required the removal of the corneal stroma,this study did not discuss this procedure.The above are the possible deficiencies of this study. |
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