Purpose: To evaluate the repeatability of a multispectral-based refractor in central and peripheral refraction measurement, and to assess the agreement of such measurements with objective refraction (OR) and subjective refraction (SR) in patients with myopia.Methods: A total of 60 subjects were recruited in this prospective research. Patients were divided into three groups according to the refractive error. Next, the central and peripheral refraction parameters were measured using multispectral refractive tomography (MRT) before and after cycloplegia. In addition, OR and SR measurements were also performed. The intraobserver repeatability was analyzed using within-subject standard deviation (Sw), test–retest repeatability (TRT), and intraclass correlation coefficient (ICC). Agreement was evaluated using Bland-Altman plot and 95% limits of agreement (LoA).Results: The ICC value of central and peripheral refraction were all higher than 0.97 with or without cycloplegia. The peripheral refraction in the nasal, temporal, superior, and inferior quadrants was slightly worse than other parameters, with the largest error interval being 1.43 D. The 95% LoA of the central refraction and OR or SR ranged from −0.89 to 0.88 D and −1.24 to 1.16 D without cycloplegia, respectively, and from −0.80 to 0.42 D and −1.39 to −0.84 D under cycloplegia, respectively.Conclusions: The novel multispectral refraction topography demonstrated good repeatability in central and peripheral refraction. However, the refraction in the nasal, temporal, superior, and inferior quadrants were not as good as that of central and circle peripheral refraction.

Background To assess the current myopia prevalence rate and evaluate the effect of sunshine duration on myopia among primary school students in the north and south of China. Methods This prospective cross-sectional study pooled data from 9171 primary school students (grades from 1 to 6) from four cities in the north and south of China. National Geomatics Center of China (NGCC) and China Meteorological Administration provided data about altitude, latitude, longitude, average annual temperature, and average annual sunshine duration. Non-cycloplegic refraction was recorded, and prevalence rates in primary school students and factors associated with myopia were analyzed. Univariate and multivariate logistic regression models were used to determine the independent association of risk factors of myopia. Results The overall myopia prevalence was 28.0%, from 7.5% to 50.6% for first and sixth grades, respectively. Low, moderate and high myopia significantly increased with school grades from 7.30% to 35.0%, 0.3% to 13.60% and 0.00% to 1.9%, respectively. Multiple regression analysis revealed that longer average cumulative daylight hours were connected to lower myopia prevalence in primary school students (OR, 0.721; 95% CI, [0.593–0.877]; P=0.001), whereas girls and higher grade was independently associated with higher myopia prevalence (girls: β=0.189; OR, 1.208; 95% CI, [1.052–1.387]; P=0.007; higher grade: β=0.502; OR, 1.652; 95% CI, [1.580–1.726]; P<0.001). Conclusion This study demonstrated that myopia was highly prevalent in southern Chinese cities over northern ones, linked to shorter light exposure, higher education level, and female gender. Such findings reinforced the beneficial impact of daylight exposure with a protective role against myopia development.

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The Beidou Radio Determination Satellite Service (RDSS) is an advantageous service of the Beidou system. However, due to the weak landing power of Beidou RDSS signals and an operating frequency close to the 5G frequency, the system is vulnerable to interference from ground signals. In this paper, from the perspective of civil aviation safety, different evaluation indicators are used for the takeoff and cruise phases, respectively, to study the impact caused by adjacent frequency interference on airborne Beidou RDSS equipment. In the takeoff phase, accurate aircraft position information is obtained by processing real trajectory files. Deterministic analysis methods are used to determine the safety distance for the coexistence of the two systems. During the cruise phase, ground-based 5G base stations have less influence on the airborne RDSS receiver due to the high flight altitude, so the main consideration is electromagnetic compatibility between the airborne Beidou RDSS system and the 5G ATG system. By establishing a Boeing 737–800 simulation model, the antenna isolation degree is used as the evaluation index, and a reasonable antenna layout is given according to the evaluation results. In this study, the theoretical simulation and real flight data are combined to summarise the exact range of adjacent frequency influence during the takeoff phase and a reasonable antenna layout during the cruise phase.