| Background The development of corneal refractive surgery has become more mature for 3 decade.After refractive surgery most patients can get good vision,but at the same time,some patients would complain about decline of visual acuity,ghost,glare and halo etc.The emergence of these conditions is closely related to the wavefront aberration.Although corneal refractive surgery has corrected the low-order aberrations(defocus and astigmatism),this way can significantly improve uncorrected visual acuity,However,the higher-order aberrations(HOAs)increased would lead to decline of the quality of visual in postoperative.While Corneal optical density as an objective indicator of corneal has been introduced into clinical.How it will change in corneal refractive surgery,whether there is a relationship between corneal optic density and higher order aberrations,this isssue still needed to be further studied.Objective we would observe that changes of corneal optical density and HOAs,meanwhile,analysis the correlation between corneal optical density and HOAs after Trans PRK.Method Between March 2017 and July 2017,80 patients of myopia and astigmatism were selected from the first affiliated hospital of Xinxiang Medical University,choosing the right eye into the study.The HOAs were measured by analyzer of Keratron Scout wavefront aberration.The Corneal optical densities were measured by Pentacam Scheimpflug system,in the same surroundings.LSD-t test was used to compare the difference between preoperative and postoperative time.Pearson correlation analysis was applied to assess the correlation between corneal optical densities and HOAs.Results 1 After Trans PRK,the operation corneal optical densities for ? 2mm diameter,> 2mm and ? 6mm,> 6mm and ? 10 mm diameter clearly increased than the preoperation during the entire follow-up period(F=143.704,P=0.000;F=95.538,P=0.000;F=8.036,P=0.000).2 After Trans PRK,values of corneal high-order aberrations Root mean square(HO-RSM),coma,spherical aberration were Significantly increased during the entire follow-up period(F=97.730,P=0.000;F=166.401,P=0.000;F=146.708,P=0.000).There was no significant difference between preoperation and postoperation of trefoil at 6 months(P=0.356),trefoil significantly increased than preoperation at 1 month and 3 months after operation(P=0.000,P=0.033).There was no significant difference between preoperation and postoperation of secondary astigmatism at 3 months and 6 months(P=0.090,P=0.324),secondary astigmatism significantly increased than preoperation at 1 month after operation(P=0.034).3 At 3 months after operation,there was a negative relationship between the change value of corneal optical density for ? 2mm diameter and the spherical aberration(R=-0.252 P=0.024),while the change value of corneal optical density for > 2mm diameter and ? 6 mm and HO-RMS coma had positive relationship(R=0.403,P=0.000;R=0.567,P=0.000).There was a negative relationship between the change value of corneal optical density for > 2 mm and ? 6 mm diameter and the spherical aberration(R=-0.607 P=0.000).4 At 6 months after operation,there were a negative relationship between the change value of corneal optical density for ? 2mm diameter and the spherical aberration(R=-0.257 P=0.021).There was a positive relationship between the change value of corneal optical density for >2 mm and ? 6 mm diameter and the coma(R=0.244,P=0.029),while there was a negative relationship between the change value of the corneal optical density for > 2 mm and ? 6 mm diameter and spherical aberration(R=-0.374,P=0.001).There was no statistical significance in the values of corneal optical density for other area and other higher order aberrations in each time interval(P>0.05).Conclusion As a objective index,corneal optical density can judge the health of the corneal.It can become the indicators that evaluate corneal conditions and postoperative recovery,and also predict or indicate the changes of HOAS in patients with corneal refractive surgery. |
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