Study On The Changes Of Subjective And Objective Visual Quality And Its Optical Mechanism Under Different Illuminations After Small Incision Lenticule Extraction

Purpose:To explore the changes of subjective visual quality under different illuminations and the optical mechanism after small incision lenticule extraction using a smart device.Methods:The partⅠwas a prospective cohort study.In our surgery center,subjects who used frame glasses or SMILE for vision correction were randomly selected.A total of 119 subjects were enrolled,including 59 using frame glasses（glasses group）and 60 using SMILE（surgery group）.Obvious optometry,questionnaire（based on NEI-RQL-42）,and visual acuity test were performed 3 months after enrollment.Wavefront aberrations were measured for the surgery group.Variables for visual acuity tests include illumination（dark and bright environment）,test distance（near and distance vision）,and visual acuity chart（normal and inverted color）.The partⅡwas a retrospective case-control study.40 subjects（40 eyes）who underwent SMILE were randomly selected.A visual quality analyzer（KR-1W）was used to measure the wavefront aberrations under mesopic and photopic illuminations before and 3 months after surgery.The compensation factor（CF）was calculated.Results:PartⅠ:Comparison between the glasses and surgery group:residual astigmatism in surgery group was greater（-0.34±0.26D,p=0.023）;near vision,distance vision,and glare scores were all higher in surgery group（p<0.001,=0.020and 0.007,respectively）;dark distance inverted VA,dark distance normal VA,bright distance inverted VA,bright distance inverted VA was better in surgery group（all p<0.001）.There were significant differences in VA under 8 conditions in glasses group（p<0.001）.Dark VA was worse than bright VA（for distance inverted VA,p<0.001）;distance VA was worse than near VA（for dark inverted VA,p=0.008）;inverted VA was worse than normal VA numerically.Residual sphere was correlated with dark distance normal VA（r=-0.429,p=0.001）,bright distance inverted VA（r=-0.266,p=0.045）,and bright distance normal VA（r=-0.540,p<0.001）;residual cylinder was correlated with bright near normal VA（r=-0.467,p<0.001）.There were significant differences in VA under 8 conditions in surgery group（p<0.001）.Dark VA was worse than bright VA（far normal VA,p=0.018）;Near VA was worse than distance VA（dark inverted VA,bright inverted VA,and bright normal VA,p=0.008,0.037,and<0.001）;inverted VA was worse than normal VA（dark near VA and bright distance VA,p=0.004 and 0.006）.Residual cylinder was correlated with dark near normal VA（r=-0.322,p=0.012）,dark distance inverted VA（r=-0.361,p=0.005）,dark distance normal VA（r=-0.426,p=0.001）,and bright near normal VA（r=-0.303,p=0.019）.Z₄⁰for 5-mm pupil was correlated with dark distance normal VA,and Z₄⁰for 3-mm pupil was correlated with bright distance normal VA.Subjects whose glare score under 50 demonstrated lower refraction and higher Z₃^-3,Z₃³,Z₃^-1,Z₃¹,and Z₄⁰.PartⅡ:Preoperatively,the eyes only had a significantly higher（p<.001）spherical refractive error under mesopic vs.photopic illumination,whereas postoperatively,the eyes also exhibited statistically significantly higher（p=.005）astigmatism.Differences in refraction between the two illuminations were the highest in postoperative eyes.Only postoperative eyes exhibited significant elevations（p<0.001）in HOAs under mesopic illumination.Only preoperative eyes exhibited significantly enhanced（χ²=6.373,p=0.01 for fourth-order andχ²=11.850,p<0.001 for Z₄⁰）and decreased(（χ²=13.653,p<0.001 for Z₃³）compensation effects under mesopic illumination.Conclusions::PartⅠ:Subjective visual quality（VA under different illuminations and questionnaire scores）after SMILE was better than those after glasses correction,but the residual astigmatism was higher after SMILE.In glasses group,spherical under-correction led to poor distance VA,and cylindrical under-correction led to poor near-reading VA.Only the residual cylindrical refractive error was related to dark and near-reading VA after SMILE.Astigmatism and spherical aberration showed opposite effects on dark distance VA.There were interactions between lower-and higher-order aberrations.Postoperative positive spherical aberration would compensate for the loss of distance VA caused by astigmatism.PartⅡ:Exaggerations myopic/astigmatic shift after SMILE became apparent under mesopic illumination.Slight under-correction may have an enhanced effect under low illumination and may reduce night VA.Exaggerations in HOAs after SMILE were also apparent under mesopic illumination,which may be the main factors for night vision symptoms.Preoperative eyes demonstrated enhanced compensation effects for 4^thorder and primary spherical aberrations and decreased compensation effects for horizontal trefoil under mesopic illumination.The changes in compensation may be a mechanism for normal eyes to maintain aberration balance and good night vision.Postoperatively,the eyes lost the specific changes in compensation under mesopic illuminations,which may diminish night vision.