Abstract:  Objective To analyze the changes in refractive status among children in the Urumqi region and to explore the characteristics of refractive status across different ethnic groups and genders. Design Prospective cohort study. Participants A cluster sampling method was used to select 1151 first-grade children aged 6 to 8 from five primary schools in Urumqi as study subjects. Among them, there were 913 children of Han nationality and 238 non-Han children, including the Uyghur, Kazakh, Hui and other ethic groups. The sample included 607 males and 544 females. Methods All participants underwent non-cycloplegic autorefraction for both eyes to calculate spherical equivalent refraction (SE). Axial length (AL) and corneal curvature (K) were measured using optical biometry, and further calculation was performed to obtain corneal radius of curvature (CR) and the AL to CR ratio (AL/CR). Myopia was defined as SE≤-0.50 D, and anisometropia as an interocular SE difference ≥ 1.0 D. The cohort was followed up for 4 years to analyze trends and differences across ethnic groups and genders. Main Outcome Measures SE, AL/CR, myopia prevalence, anisometropia prevalence, Odds Ratios (OR). Results At baseline, the average age of the study subjects was (7.01±0.43) years, with 79.3% being of Han nationality and 52.7% being male. The overall myopia rate increased from 25.1% to 61.8% over 4 years, with the myopia rate among Han children rising from 26.0% to 64.3%, a higher increase than that observed among non-Han children, whose rate rose from 21.8% to 51.7% (P=0.001). The overall SE decreased from (-0.08±1.07) D to (-1.33±1.87) D, with the SE among Han children decreasing from (-0.11±1.10) D to (-1.45±1.93) D, a larger decrease than that observed among non-Han children, whose SE changed from (0.06±0.93) D to (-0.87±1.57) D (P<0.001). The rate of anisometropia increased from 10.0% to 21.2%, and from grades 3 to 5, the rate of anisometropia among Han children (13.5%, 20.7%, 22.8%) was significantly higher than that among non-Han children (8.1%, 11.7%, 14.9%) (P=0.033, 0.003, 0.014). Risk factor analysis indicated that Han nationality (OR=2.155) and a higher AL/CR (OR=2.106) were independent risk factors for new-onset myopia, while non-Han nationality (OR=0.522), male sex (OR=0.631), and a higher baseline SE (OR=0.489) had protective effects. Conclusion Four years of follow-up observation have shown that the prevalence of myopia among children in the Urumqi region increases rapidly with age. Han Chinese children face a higher risk of developing both myopia and anisometropia. The AL/CR is a significant biological indicator in predicting the onset of myopia. Han and non-Han children exhibit distinct developmental patterns in these conditions.

Key words: Children, Myopia, Anisometropia