Vector Analysis Of Whole Astigmatism And Ocular Residual Astigmatism Under Different Illumination

Purpose: This research adopts vector analysis method to research in normal myopia patients,whether there is any change of astigmatism and its horizontal and vertical,oblique direction vector under different light intensity.Using vector analysis to compare the difference between whole astigmatism,corneal astigmatism and ocular residual astigmatism(ORA)under different illumination.The ORA and its J0 and J45 directions were compared with those patients who received SMILE,and the changes of ORA were observed before and after SMILE to explore whether light intensity had an effect on ORA in patients with SMILE before and after the operation.This research can provide a basis for clinical research.Methods: Retrospective study.There's 225(225 eyes)of myopia and astigmatism patients were enrolled.The patient's spherical,cylindrical,axial,and dioptric wavefront aberrations were measured using a Topcon KR-1W wavefront analyser which has a computer optometry system.The vector properties of astigmatism were analyzed using the Thibos vector analysis method.In the plane Cartesian coordinate system,the astigmatism axis is changed to the original angle,and the ocular residual astigmatism(ORA)is calculated by using the Alpins doubling angle vector operation method.For the data which do not meet the normality we use Kruskal-Wallis H nonparametric test for comparison between groups.The correlation between the parameters was analyzed using Spearman correlation analysis.P <0.05 for the difference was statistically significant.Results: 1.Comparing all optometry results of the eyes under different illumination,the result was P> 0.05,that means,when under different illumination,the spherical lens,cylinder,axial,equivalent spherical,J0 and J45 vector of patients have no significant difference.2.There was no significant difference in Sim K,ORA,J0,J45 vectors and axial position between different groups(P >0.05)3.There was a significant correlation between ORA-Sim K group(P <0.05),and the strongest correlation was the third groups(P <0.01).There also a strong correlation between the whole astigmatism and Sim K(P <0.01).Whereas the astigmatism-ORA was not founded association(P> 0.05).4.The ORA,J0 and J45 vectors in high ORA group and the low ORA group,and also have no significant difference between with-the-rule astigmatism and agnist-the-rule astigmatism group when under different illumination(P> 0.05)5.The spherical,cylinder,axis and equivalent spherical in patients who received cornea refrective surgury after 1 month have no significant difference when under different illumination(P> 0.05).Then we contrast of ORA,J0 and J45 vector of patients before and after the operation,there was have no significant difference in two groups(P> 0.05).Conclusions: 1.There was a strong correlation between corneal astigmatism and whole astigmatism.In addition,there was a correlation between corneal astigmatism Sim K and ORA,and the correlation in illumination 3(0.84lx)was the strongest.There was no statistically significant difference between Sim K and ORA group.2.There were no statistically significant differences in the spherical,cylindrical,axial,and equivalent spherical,J0 and J45 vectors of the subjects under different illumination.3.There was no statistically significant difference in ORA,J0,J45 vector when contrast between preoperative and postoperative patients.