Morphological Changes Of The Fundus And The Associated Factors In Children And Adolescents With Myopia

Purpose:To explore the changes of choroidal thickness(Ch T)in the posterior pole,the changes of subfoveal scleral thickness(SST)and the changes of asymmetry of retinal layers in the macular region in myopic children and adolescents,and to clarify their relationship with refractive level as well as other parameters.Methods:(1)Children and adolescents from Yuepu experimental school,Shanghai,were included in the study.The age range was 9 to 16 years old.Comprehensive ocular examinations were performed,including measurement of visual acuity,intraocular pressure and axial length,as well as optometry and swept-source optical coherence tomography(SS-OCT)after cycloplegia.Radial scan mode focusing on the fovea and the center of optic disc was adopted in the SS-OCT examination,each scan line being 12 mm.Ch Ts in different regions of the posterior pole were calculated automatically by the built-in software.(2)Children and adolescents from 12 schools in the Jiading and Songjiang districts were included.The age range was 6 to 19 years old.General characteristics including height and weight were recorded.Comprehensive ocular examinations were performed,including measurement of visual acuity,intraocular pressure and axial length,as well as optometry and SS-OCT after cycloplegia.Radial scan mode focusing on the fovea was adopted in the SS-OCT examination,each scan line being 12 mm.Subfoveal retinal thickness(SRT),subfoveal choroidal thickness(SCT)and SST were measured manually.(3)Source of participants and methods for data collection were identical with(2).Thicknesses of GCL+layer(retinal ganglion cell layer+inner plexiform layer),GCC layer(GCL+layer+retinal nerve fiber layer)and the neural retina in different macular regions were measured automatically by SS-OCT.Asymmetry index(AI)for each layer was calculated by the formula:AI=|log₁₀(superior/inferior hemiretinal layer thickness)|.Results:(1)The mean Ch T in the central foveal,parafoveal and perifoveal regions were(229±65)?m,(227±60)?m and(215±50)?m,respectively,and the mean global peripapillary choroidal thickness was(136±33)?m.The choroid in the macular region was thinner in myopes compared to hyperopes.The area between the central fovea and the optic disc underwent the largest change as myopia worsened.Sperical equivalent(SE),uncorrected visual acuity,cornea radius of curvature(CR),retinal thickness(RT),and retinal nerve fiber layer thickness(RNFLT,except for the central fovea)were the independent factors of Ch T in the macular region.SE,CR,RT and RNFLT were the independent factors of Ch T in the peripapillary region temporally and inferiorly,while only CR,RT and RNFLT were independently associated with Ch T in the peripapillary region superiorly and nasally.(2)The mean SST,SCT,and SRT were(524±57)?m,(195±49)?m and(224±19)?m,respectively.The SST and SCT of myopes were significantly thinner than those of emmetropes and hyperopes,while no statistical significant difference was observed between emmetropes and hyperopes.Thinner SST and SCT were associated with greater levels of myopia,whereas the SRT was similar in children with different refractive levels.SST and SCT as well as age,gender and axial length were independently associated with SE.Older age,myopic-shifted SE,thicker SCT and thinner SRT,were independently associated with a thinner SST.(3)The AI of all layers were larger in myopes than that in hyperopes and emmetropes in the perifoveal region,while no statistical significant difference was observed among different refractive groups in the parafoveal region for all AI.Difference of AI among refractive groups was more obvious in the GCL+and the neural retina than that in the GCC.Linear regression analyses indicated that the asymmetry of retinal layers increased in the perifoveal region and slightly decreased in the parafoveal region with the increase of degree of myopia.Conclusion:Choroidal thinning in the posterior pole might be uneven during the development of myopia.SE only influenced the macular area and sectors temporal and inferior to the optic disc in the early stage of myopia.Ch T in the superior and nasal peripapillary region was not associated with SE.The SST became smaller as the degree of myopia increased.Age,refractive error,SCT and SRT were independently associated with SST.The asymmetry of retinal layers increased in the perifoveal region with the increase of degree of myopia,while no statistically significant difference was observed in the parafoveal region among different refractive groups.