Demographic and biometric at baselines.

PurposeThis study aimed to investigate the underlying factors driving the onset of myopia, specifically the role of the ciliary muscle’s contraction in the elongation of the axial length of the eye.MethodsThe retrospective study was conducted utilizing data from three ophthalmic centers in Shanghai and Beijing. Both Chinese and Caucasian children were involved. The axial length of the subjects’ eyes was measured in both relaxed and contracted state of the ciliary muscle. A comprehensive mechanical model was also developed to observe the influence of ciliary muscle contraction on the axial length.ResultsThis study included a sample of 198 right eyes of 198 myopic children. Of these, 97 were male and 101 were female, 126 were of Chinese ethnicity and 72 were Caucasian. The age of onset for myopia ranged from 5.9 to 16.9 years old. The axial length of the eye decreased 0.028 ± 0.007mm following dilation, indicating relaxation of the ciliary muscle (t paired student = 15.16, p = 6.72 x 10−35). In contrast, ciliary muscle contraction resulted in an increase in axial length. Considering proportionality, a significant 90.4% (179 eyes) exhibited a reduced axial length, while a minor 9.6% (19 eyes) demonstrated an increase post-mydriasis. Finite element modeling demonstrated that muscle contraction caused a tension force that transmits towards the posterior pole of the eye, causing it to extend posteriorly.ConclusionThe contraction of the ciliary muscle leads to an extension of the axial length. This could potentially be the initiating factor for myopia.研究目的 本研究旨在探究驱动近视发生的潜在影响因素，重点关注睫状肌（ciliary muscle）收缩在眼轴长度（axial length）延长过程中所发挥的作用。 研究方法 本回顾性研究纳入上海与北京三家眼科中心的临床数据，研究对象涵盖中国儿童与白种人儿童。研究人员对所有受试者的双眼分别在睫状肌松弛与收缩状态下测量眼轴长度。此外，本研究还构建了一套完整的力学模型，用以观测睫状肌收缩对眼轴长度的影响。 研究结果 本研究共纳入198名近视儿童的右眼样本，其中男性97例、女性101例；中国籍受试者126例，白种人受试者72例。近视发病年龄跨度为5.9至16.9岁。散瞳后睫状肌处于松弛状态，此时眼轴长度较基线降低0.028±0.007mm（配对t检验t值=15.16，p=6.72×10⁻³⁵）。与之相反，睫状肌收缩会导致眼轴长度增加。按比例统计，90.4%（179眼）的受试者在散瞳后眼轴长度缩短，仅9.6%（19眼）表现为眼轴长度增加。有限元建模（finite element modeling）结果显示，肌肉收缩产生的张力可传导至眼球后极部，导致其向后扩张。 研究结论 睫状肌收缩可导致眼轴长度延长，这或为近视发生的始动因素。