| Objective:To investigate the differences in the variation of ocular biological parameters in school-aged children with different refractive status over the course of 12 months of follow-up.Methods:A prospective cohort study was conducted to enroll 299 school-aged children aged 6 to 12 years from December 2020 to July 2021,all of whom had not previously used any other means of myopia control other than monofocal frames and had no strabismus or other ocular diseases.The children were enrolled and completed baseline ocular biology tests,including uncorrected visual acuity,intraocular pressure,axial length,corneal radius,anterior chamber depth,central corneal thickness,cycloplegic refraction,and enhanced depth imaging optical coherence tomography(EDI-OCT).Follow-up was performed at the 6th and 12 th month after enrollment,and the same exams were performed as at enrollment.In addition,15 participants were failed to participate in the 6th month follow-up due to the personal reason,however,participated again in the 12 th month follow-up.At the 12 th month,51 participants were excluded from the study because they could not complete the follow-up on time,with a lost rate of 17.06%.Because of a high degree of correlation between biological parameters in the bilateral eyes,the subsequent studies took data from the right eye for analysis.The final analysis included 299 participants(299 eyes),284 participants(284 eyes),and 248participants(248 eyes)at baseline,month 6,and month 12 data,respectively.Spherical equivalent(SE)was calculated based on the results of cycloplegic refraction.The enrolled 299 children aged 6 to 12 years were divided into 3 different refractive status groups by SE: myopic group(-0.5D≥SE>-6.0D,n=121 participants,121 eyes),premyopic group(6 years old: +0.75D≥SE>-0.5D,7 to 8 years old: +0.5D≥SE>-0.5D,9to 10 years old: +0.25D≥SE>-0.5D,11 to 12 years old: +0.0D≥SE>-0.5D,n=70 participants,70 eyes),and hyperopic reserve group(+2.0D to +0.75 D,+0.5D,+0.25 D,+0.0D,n=108participants,108 eyes).SE was used as the primary follow-up target,and axial length(AL)and subfoveal choroid thickness(SFCT)were the secondary follow-up targets.Generalized estimating equations were used to analyze the difference of SE,AL,and SFCT changes in school-aged children with different refractive status and time of follow-up,after adjusting for age,and the interaction of the different refractive status and time of follow-up,in addition to the effect of AL,SFCT,and age on the SE changes.Finally,risk ratio(HR)of new-onset myopia in the non-myopic children(hyperopic reserve,premyopic group)during the follow-up period was analyzed using a Cox regression equation to adjust age.Furthermore,the SE of non-myopic children were divided into 5 layers with a stepped gradient of 0.5D,from +2.0D to-0.5D.The cumulative myopia incidence at month 6 and month 12 was calculated for each layer of SE,separately.Results:1.The trends of SE,AL,and SFCT changes differed among school-aged children in the refractive status groups during the 12-month follow-up.From baseline to month 6,the mean change in SE was in the order of myopic group> premyopic group> hyperopic reserve group(-0.28±0.04 D,-0.13±0.05 D,-0.12±0.04 D,respectively).From month 6 to month 12,the change in SE mean value was in the order of myopic group≈premyopic group> hyperopic reserve group(-0.37±0.01 D,-0.37±0.01 D,and-0.21±0.01 D,respectively).From baseline to month 12,the SE change in mean value was in the order of myopic group> premyopic group> hyperopic reserve group(-0.65±0.04 D,-0.50±0.05 D and-0.34±0.04 D,respectively).The significant differences were all statistically significant(all P values<0.05).For the secondary follow-up target AL,from baseline to month 6,the mean increase in AL was in the order of myopic group>premyopic group> hyperopic reserve group(0.22±0.02 mm,0.20±0.02 mm and0.13±0.02 mm,respectively).From month 6 to month 12,the mean increase in AL was in the order of premyopia group> myopia group> hyperopia reserve group(0.18±0.02 mm,0.13±0.02 mm and 0.12±0.02 mm,respectively).From baseline to month 12,the mean AL increase was in the order of premyopia> myopia> hyperopia reserve(0.38±0.04 mm,0.34±0.03 mm and 0.25±0.03 mm,respectively).The differences were all statistically significant(all P values<0.001).For the secondary follow-up marker SFCT,the mean change in SFCT from baseline to month 6 was in the following sequence: premyopic group>hyperopic reserve group> myopic group(-5.01±0.87μm,-0.91±0.71μm and-0.70±0.65μm,respectively).From month 6 to month 12,the amount of change in the mean SFCT value was in the following sequence: hyperopic reserve group>premyopic group>myopic group(-3.58±2.77μm,-1.61±2.96μm,-0.23±3.34μm,respectively).From baseline to month 12,the amount of change in mean SFCT values was in the following order: premyopic group>hyperopic reserve group> myopic group(-5.23±2.99μm,-4.49±2.49μm,and-2.31±2.74μm,respectively).The statistically significant difference in the mean value of SFCT change at month 6 was only found in the premyopia group(P<0.001),while the rest of the time points in the premyopia group and the time points in the myopic and hyperopic reserve groups were not statistically significant(all P values>0.05).2.Controlling for age factors,different refractive status school-age children had different degrees of influence of AL on SE change,and SFCT had no effect on SE change.For each 1-mm increase in AL in school-age children in the myopic group,SE advancement was-1.169D;for each 1-mm increase in AL in the premyopic group,SE variation was-0.45D;for each 1-mm increase in AL in the hyperopic reserve group,SE change was-0.22 D.3.The risk of new-onset myopia at 12 months increased 1.922-fold for each 1-mm increase in AL in non-myopic school-age children with the same SE,controlling for age factors,and the risk of new-onset myopia at 12 months was 5.113-fold higher in the premyopic group than in the hyperopic reserve group.Meanwhile,baseline SE was divided into 5 layers with a grading of 0.5D(in sequence:-0.5D<SE≤+0.0D,+0.0D<SE≤+0.5D,+0.5D<SE≤+1.0D,+1.0D<SE≤+1.5D and +1.5D<SE≤+2.0D),and the6-month cumulative incidence of myopia in each layer of SE was 53.85%,2.86%,0%,0%,and 0%,respectively,and the 12-month cumulative incidence of myopia: 78.95%,32.26%,8.89%,2.63%,and 0%,respectively.Conclusions:1.During the 12-month follow-up of school-age children,SE progressed faster in the myopic group,AL and SFCT changed faster in the premyopic group,however,SE,AL and SFCT showed relatively flat changes in the hyperopic reserve group.2.The degree of influence of AL on SE change varied among school-age children with different refractive status.For each 1-mm increase in AL in the myopic group of school-age children,SE progressed-1.169 D,for each 1-mm increase in AL in the premyopic group,SE varied-0.45 D,and for each 1-mm increase in AL in the hyperopic reserve group,SE changed-0.22 D.3.The effect of AL on SE changes varied in degree among school-age children with different refractive status.For every 1 mm increase in AL in the myopic group of school-age children,SE progressed-1.169 D,for every 1 mm increase in AL in the premyopic group,SE varied-0.45 D,and for every 1 mm increase in AL in the hyperopic reserve group,SE changed-0.22 D.4.In non-myopic school-aged children,the risk of new-onset myopia at 12 months increased 1.922-fold for each 1-mm increase in AL with the same SE,and the risk of new-onset myopia at 12 months was 5.113-fold higher in the premyopic group than in the hyperopic reserve group. |
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