| Objective:To explore the effects of Low-Level Red-Light therapy on choroidal thickness in different regions of children and choroidal capillary blood flow density changes in macular areas,and to further explore the predictive effect of choroidal thickness on myopia progression in children’s natural myopia process,and the direct effect and prediction ability of choroidal thickness change on myopia prevention and control after using red light therapy,so as to provide new ideas for clinical myopia prevention and control.Methods: Children aged 7-12 years who attended the Department of Ophthalmology of the First Affiliated Hospital of Kunming Medical University from October 2020 to July 2021 were recruited,and children with cycloplegic refractive power +0.75 D to-6.00 D were randomly assigned to the red light group or control group.The children in the red light group received red light treatment twice a day,and the control group was routinely followed.At the beginning of the trial and regular follow-up examinations at the 1st,3rd,6th,and 12 th months,choroidal tomography images were obtained by using the fundus optical coherence tomography angiography device RTVue Angio-OCT(RTVue XR Avanti,Optovue,Inc.,Fremont,CA,USA)scanning,and the choroidal thickness at different locations was manually measured using the linear measurement tool included with the inspection device;The En-face images of the choroidal capillaries in the macular area were obtained.After binary processing,the percentage of blood flow signal in the whole area was analyzed,which was the choroidal capillary density.The IOL-Master 700 optical biometer(Carl Zeiss,Germany)was used to measure ocular biological parameters such as axial length,central anterior chamber depth,and corneal curvature.The refractive state of the eye after cycloplegia was evaluated by automatic computerized refractometry(Topcon),and the results were converted into equivalent spherical lens power(SE)= spherical lens power + cylindrical lens power / 2(DS+1/2DC).The questionnaire survey recorded the children’s family factors and congenital conditions,height,weight,subjects’ eye habits,outdoor activity time,sleep duration,academic performance,etc.Results: A total of 200 children were included in the study,and the children were randomly assigned to the red light group and the control group,and all the results were obtained from the analysis of the right eye.There were no significant differences between the red group and the control group in age,sex,height,weight,and baseline diopter(P>0.05).At the beginning of the study and regular follow-up at the 1st,3rd,6th and 12 th months of the study,there was no significant difference in the thickness of the subfoveal choroid between the red light group and the control group at baseline(P=0.790),and the increase in the thickness of the subfoveal choroid in the red light group was statistically significant compared with the change in the control group at the first month of follow-up(P=0.006),and the thickness of the subfoveal choroid in the red light group continued to increase during the one-year follow-up.The thickness of the subfoveal choroid in the control group continued to decrease.At the beginning of the study and at one year of study,the choroidal thickness of 500 μm,1000 μm,2000 μm and 3000 μm from the fovea of the macula was detected at the beginning of the study and at one year of study,and the choroidal thickness of each region was significantly thickened compared with the baseline when the children in the red light group were followed for one year,and the difference was statistically significant at any position(P<0.05).At 1 year of follow-up,the choroidal thickness in all regions was thinner than the baseline,and these changes were statistically different anywhere except I3000(P<0.05).The differences in choroidal thickness in different regions at baseline and one year of follow-up in the enrolled children were compared,and the choroidal thickening at N3000 in the red group was at least different from the choroidal thickening at other locations,and the difference was statistically significant between N3000 and fovea,T2000,T3000,S500,S1000,S2000,S3000,I500,I1000,I2000,and I3000(P<0.05).There was no significant difference in choroidal thickness in different regions of the control group(P=0.616).At the beginning of the study and regular follow-up at the 1st,3rd,6th and 12 th months of the study,the choroidal capillary blood flow density of the macular area of the red light group and the control group was checked,and the choroidal capillary blood flow density of the red light group was slightly larger than that of the control group at baseline and the first month of follow-up,and the difference was statistically significant(P<0.05).During the follow-up of the red light group,there were significant differences in choroidal capillary blood flow density at baseline compared with the choroidal capillaries at the3 rd,1st and 3rd and 6th months(P<0.05).During the follow-up of the control group,there was no significant difference in choroidal capillary blood flow density at any time point(P>0.05).The correlation between the changes of subfoveal choroidal thickness in the red light group and the control group was analyzed with age,sex,baseline and one year of height,weight,intraocular pressure,diopter,choroidal capillary blood flow density,ocular biometric parameters,children’s eye habits and family factors,and the change of subfoveal choroidal thickness in the red light group was positively and linearly correlated with the change of diopter(low correlation),and negatively and linearly correlated(weakly correlated)with K1,K2 and father’s myopia.The change of subfoveal choroidal thickness in the control group was negatively and linearly correlated with the change of choroidal capillary blood flow density(low correlation),and the above correlations were statistically significant(P<0.05).The AUC of the baseline subfoveal choroid thickness in the control group to judge the progression of myopia was 62.5%,and the 95% confidence interval was0.511～0.739,and it was easy for myopia to progress when the subfoveal choroid thickness was lower than 308.5μm in children aged 6-14 years.The effects of age,sex,baseline eye axis or diopter,and subfoveal choroidal thickness changes on diopters and annual changes in the ocular axis in the red light group were analyzed: the effects of age,sex and baseline eye axis on the annual change of eye axis in the univariate linear regression model were statistically significant,and the effects of age and baseline diopter on the annual change of diopter were statistically significant.In the "Multiple Linear Regression Model 1",the effect of baseline eye axis and baselineJanuary choroidal thickness change on the annual change of eye axis was statistically significant(P<0.05),and the effect of baseline diopter on annual change of diopter was statistically significant(P<0.05).In the "Multiple Linear Regression Model 2",there was a significant effect of baseline eye axis and baseline-3 choroidal thickness change on the annual change of ocular axis(P<0.05),and the effect of baseline diopter and baseline-3 choroidal thickness change on annual diopter change was statistically significant(P<0.05).In the "Multivariate Logistic Regression Model",the "annual variation of AL<0mm" model(χ~2=13.034,P=0.011)and the "negative SE annual progression <0D" model(χ~2=11.811,P=0.019)were statistically significant.The "AL annual variation <0mm" model was able to correctly classify 76.5% of the study subjects,with a sensitivity of 46.2%,a specificity of 76.1%,a positive predictive value of 68.4%,and a negative predictive value of 62.5%;Among the four independent variables included in the model,the change in choroidal thickness from baseline to 3 months was statistically significant(P=0.006),and the possibility of annual choroidal elongation less than 0mm increased by 37.9% for every 10μm increase in choroidal increase compared with baseline.The "negative SE annual progression <0D" model model was able to correctly classify 69.4% of the research subjects,with a sensitivity of 72.7%,a specificity of 65.9%,a positive predictive value of 72.7%,and a negative predictive value of 69.2%.Among the four independent variables included in the model,the change in choroidal thickness from baseline to March was statistically significant(P=0.010),and the likelihood of annual progression of negative diopter <0D increased by 38.8% for every 10 μm increase in choroidal increase at 3 months compared with baseline.The "Generalized Linear Model 1" that included all enrolled children "choroidal thickness change,baseline age,sex,baseline eye axis or diopter" within one year indicated that each 10 μm thickening of the choroid thickness was negatively affected by 0.035 mm and the negative diopter progression by 0.082 D,and the "Generalized Linear Model 2" which included "whether to use red light therapy" indicated that each 10 μm thickening of the choroid thickness was 0.019 mm longer than the eye axis,The negative diopter progression of 0.047 D showed a negative effect;the "Generalized Linear Model 2" of annual axial lengthening pointed out that the risk of axial lengthening with red light therapy was 0.164 times that of unused red light therapy,and the "Generalized Linear Model 2" of annual negative diopter progression pointed out that the risk of negative diopter progression with red light therapy was 0.350 times that of unused red light therapy,that is,red light therapy has a protective effect on myopia prevention and control.Conclusion:1.Children treated with Low-Level Red-Light therapy continued to increase the subfoveal choroid thickness during follow-up,and the choroid thickness of all detection points within 3000 μm of the macular fovea increased significantly.2.There was no significant change in choroidal capillary blood flow density after Low-Level Red-Light therapy,and the change of choroidal capillary blood flow density after red light therapy had no correlation with the change of choroidal thickness,and it was speculated that the improvement of choroidal blood flow after red light therapy was mainly concentrated in large and middle vascular layers.3.In the process of natural myopia after one year of follow-up,the choroid thickness in the range of 3000 μm under the fovea and parafovea in children became thinner,and it was easy for myopia to progress when the thickness of the subfoveal choroid was less than 308.5 μm in children aged 6-14 years.4.The effect of red light treatment on myopia prevention and control for 1 year can be predicted by the change of choroid thickness at 3 months of red light therapy:for every 10μm increase in choroidal membrane after 3 months of red light therapy,the possibility of annual eye axis prolongation stagnation or no progression of myopia increases by 37.9-38.8%.In addition,red light therapy can effectively reduce the risk of myopia development,and the risk of myopia progression with red light therapy is0.164-0.350 times that of non-red light therapy. |
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