RESUMO
AIM: To investigate the characteristics of changes in corneal epithelial thickness at the early postoperative stage of femtosecond assisted laser in situ keratomileusis(FS-LASIK)and its related influencing factors.METHOD: Retrospective study. A total of 120 patients(240 eyes)of myopia undergoing FS-LASIK from May 2021 to June 2022 were selected. The corneal epithelium thickness in the central area, inner ring area, and outer ring area of patients before and at 1d, 1wk, 1 and 3mo after operation was recorded. The relationship between the variation of corneal epithelium thickness and spherical equivalent, optical zone diameter, depth of cut and cutting ratio was analyzed by Pearson correlation.RESULTS: There was no statistical significance in corneal epithelial thickness in the central area, inner ring area and outer ring area at 1d after FS-LASIK compared with that before operation(P>0.05). At 1wk, 1 and 3mo after surgery, the corneal epithelial thickness in the central area, inner ring area and outer ring area increased compared with that before surgery, and the corneal epithelial thickness in the central area and inner ring area at 1 and 3mo after surgery was greater than that in the outer ring area(all P<0.05). The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thicker than that of low and moderate myopia patients before operation. The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thinner than that of low and moderate myopia patients at 1wk after operation(P<0.05). At 1 and 3mo after operation, the corneal epithelial thickness in the central, inner and outer ring areas of patients with high myopia was greater than that of patients with low and moderate myopia, and the changes of corneal epithelial thickness in the central, inner and outer ring areas were greater than those of patients with low and moderate myopia(P<0.05). The results of Pearson correlation showed that the changes in corneal epithelial thickness in the central and inner ring area were positively correlated with the corneal curvature, depth of cut and cutting ratio at 3mo after surgery, and they were in negative correlation with the age, spherical equivalent and optical zone diameter(P<0.05).CONCLUSION: The corneal epithelial thickness of patients thickened after the FS-LASIK operation, and it was correlated with age, corneal curvature, preoperative depth of cut, cutting ratio, spherical equivalent and the optic zone diameter.
RESUMO
Chemical modification is critical for the therapeutic applications of antisense oligonucleotides. Novel 4'-C-MOE and 2'-fluoro-modified monomer 2'-F-4'-C-MOE-araU and its epimeric 2'-F-4'-C-MOE-rU were synthesized from 2'-fluorinated arabinourine (2'-F-araU) and 2'-fluorouridine (2'-F-rU), respectively. Their phosphoramidites were synthesized and successfully incorporated into oligodeoxynucleotides. The mismatch discrimination ability of these unnatural monomers and their effect on thermal stability were evaluated in the context of dsDNA and DNA-RNA chimeras. The thermal denaturation studies showed that the incorporation of 2'-F-4'-C-MOE-araU led to enhanced binding affinity to complementary RNA strand and almost equivalent binding ability to complementary DNA, when compared with 2'-F-4'-C-MOE-rU and 2'-F-araU modified duplexes.Especially a C-H…F-C pseudohydrogen bond was supposed to contribute more binding affinity at uridine-purine steps, meanwhile, 2'-F-4'-C-MOE-araU had almost the same base discriminatory ability as uridine in dsDNA and DNA-RNA chimeras, while 2'-F-4'-C-MOE-rU was found to have only moderate RNA hybridization ability. However, 2'-F-4'-C-MOE-araU at 3'-end of oligonucleotide could not led to more nuclease hydrolytic stability than that with 2'-F-4'-C-MOE-rU modification. These results demonstrated the feasibility of C4'-MOE modification on 2'-F-ANA and the dramatic effects of the 2'-F substituent, which provides a new approach fo r further chemical modification of antisense drugs.