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AlM: To research the characteristics of positive relative accommodation ( PRA) , negative relative accommodation (NRA) and PRA/NRA ratio in myopes. To analyze the relationship among PRA, NRA, PRA/NRA ratio, spherical equivalent degree, years and habbits of wearing glasses, myopia development, and pupil diameter.METHODS: Aretrospective study of ninety eyes in the 180 th Hospital of Quanzhou from August 2014 to December 2014. PRA, NRA and PRA/NRA ratio were compared among low, moderate, high myopes and emmetropes. The correlation were analyzed among PRA, NRA, PRA/NRA ratio, spherical equivalent degree, years and habbits of wearing glasses, myopia development and pupil diameter. PRA, NRA, PRA/NRA ratio, years and habbits of wearing glasses and pupil diameter were compared between progress group and non-progress group.RESULTS: ( 1 ) Without statistical differences in age, sex and intraocular pressure, PRA and PRA/NRA ratio of myopes were lower than emmetropes, while NRA was higher. (2) Without statistical differences in age, sex and intraocular pressure, PRA, PRA/NRA ratio and NRA had no statistical differences while years and habbits of wearing glasses had statistical differences among low, moderate, high myopes. ( 3 ) With longer years of wearing glasses, PRA, PRA/NRA ratio were larger and NRA, pupils were smaller. ( 4 ) Without statistical differences in age, diopter and intraocular pressure, one group which were not easy to deepen degree had more often-wear-glasses myopia patiens and longer years of wearing glasses, the other group which were easy to deepen degree had more seldom-wear-glasses myopia patiens and shorter years of wearing glasses.CONCLUSlON: PRA and PRA/NRA ratio of myopes were lower than emmetropes, while NRA was higher. No correlated relation was detected among PRA, NRA, PRA/NRA ratio, spherical equivalent degree and myopia development. lt suggests the onset and progress of myopia are related to many factors. Wearing-glass timely and accurately can release the decline of PRA and PRA/NRA ratio and slow down degree development in myopes.
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AIM:To discuss the related factors that affected the stability of posterior corneal surface after laser in situ keratomileusis ( LASIK) . METHODS:About 64 patients (64 eyes) were enrolled. The correlation among the changes in posterior corneal surface 6 month after LASIK, surgery method, corneal flap thickness ( FT ) , ablation thickness ( AT ) , postoperative residual corneal stroma thickness ( RCST ) , preoperative thinnest corneal thickness ( CT ) , flap thickness/preoperative thinnest corneal thickness ( FT/CT ) , ablation thickness/preoperative thinnest corneal thickness ( AT/CT) , postoperative residual corneal stroma thickness/preoperative thinnest corneal thickness ( RCST/CT) , anterior and posterior preoperative corneal height, the difference of the forward shift in posterior corneal surface ( diff value ) of preoperative and preoperative intraocular pressure were analyzed. RESULTS: The changes of diff value between preoperative and postoperative were related with diopter (r=0.419, P=0.014), AT (r=0.394, P=0.023), AT/CT (r=0.501, P=0.004), Diff value of preoperative (r=0.501, P=0. 004), RCST (r=-0. 385, P=0. 033) and RCST/CT (r=-0. 401, P=0. 025). The changes of height value from posterior corneal surface between preoperative and postoperative were related with diopter (r=0. 520, P=0. 002), AT (r=0.504, P=0. 003), AT/CT (r=0. 442, P=0. 013), Diff value of preoperative (r=0. 624, P=0. 000) and RCST/CT (r=-0. 394, P=0. 028). CONCLUSION: AT, RCST, AT/CT, RCST/CT and diff value of preoperative should be the key index that predicted the stability of posterior corneal surface after LASIK,the further research will give the range of safety value.
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Tridentate carborane [S, S, O] ligands 2a-2b [(HOC6H2R2-4,6)(CH2)SC(B10H10)C(Ph)2P=S, R = (t)Bu (2a), R = Me (2b)] were synthesized and characterized. Reaction of CrCl3(THF)3 with the sodium salts of ligands 2a and 2b afford six-coordinated chromium complexes 3a and 3b. EXAFS spectroscopy performed on complex 3a to describe the coordination chemistry of ligand 2a around chromium center. DFT calculations were also performed on complex 3a to analyze the structure. The preliminary screening results revealed that six-coordinated chromium complexes 3a-3b displayed good catalytic activities towards ethylene polymerization in the presence of modified methylaluminoxane. The effect of polymerization parameters such as cocatalyst, reaction temperature, ethylene pressure, and reaction time on polymerization behavior were investigated in detail. The polymer obtained from this homogeneous catalytic reaction has a fibroid morphology.
