ABSTRACT
Objective@#To investigate the prevalence and associated factors of unaided visual impairment and myopia among primary and secondary school students in Yunnan Province, and to provide scientific basis for myopia prevention.@*Methods@#The study was conducted among primary and secondary school students in Mangshi, Yunnan Province from March to August, 2014. All the 7 681 subjects underwent detailed eye examinations and a questionnaire survey. Myopia was defined as spherical equivalent value of less than -0.5 diopters. Unaided visual impairment was analyzed on the basis of the better and the worse-seeing eye, respectively.@*Results@#The prevalence of myopia and high myopia were 39.1% and 0.6%. The prevalence of unaided visual impairment was 11.4% based on the worse-seeing eye. Refractive errors accounted for 87.3% of the participants with unaided visual impairment. Prevalence of myopia was higher in girls than in boys (χ2=29.74, P<0.01), but there was no gender difference in high myopia (P=0.19). The prevalence of myopia and high myopia increased significantly with increasing age (χ2=351.23, 22.56, P<0.01). Besides, prevalence of myopia was 63.7% in Dai nationality students and 36.6% in Yi nationality students (χ2=78.14, P<0.01), which was higher than other ethnic minorities. After adjusting for the effects of sex, age and ethnicity, the presence of myopia was associated with increasing height (OR=1.02, 95%CI=1.01-1.03), computer use (OR=1.17, 95%CI=1.03-1.32), having a myopic father (OR=1.56, 95%CI=1.24-1.94), having a myopic mother (OR=1.33, 95%CI=1.08-1.63) and more time reading(OR=1.18, 95%CI=1.09-1.28). High myopia was found to be more prevalent in children who had a myopic father (OR=3.98, 95%CI=1.72-9.22) and using computers (OR=2.31, 95%CI=1.17-4.57).@*Conclusion@#Myopia and unaided visual impairment is prevalent in school students in rural China (Yunnan), though the prevalence is relatively lower compared with other areas in China. Attention should be paid to the formulation and input of primary eye care policies.
ABSTRACT
Genetic information of polymerase chain reaction (PCR)-based markers, one of the main tools of genetics and genomics research in wheat, have been well documented in wheat. However, the physical position in relation to these markers has not yet been systematically characterized. Aim of this study was to characterize the physical information of thousands of widely usedmolecular markers.We first assigned 2705 molecular markers to wheat physical map, of which 86.1% and 84.7% were the best hits to chromosome survey sequencing (CSS) project (CSS-contigs) and International Wheat Genome Sequencing Consortium Reference Sequence v1.0 (IWGSC RefSeq v1.0), respectively. Physical position of 96.2% markers were predicated based on BLAST analysis, were in accordance with that of the previous nullisomic/aneuploidy/linkage analysis. A suggestive high-density physical map with 4643 loci was constructed, spanning 14.01 Gb (82.4%) of the wheat genome, with 3.02Mb between adjacent markers. Both forward and reverse primer sequences of 1166 markers had consistent best hits to IWGSC RefSeq v1.0 based on BLAST analysis, and the corresponding allele sizes were characterized. A detailed physical map with 1532 loci was released, spanning 13.93 Gb (81.9%) of the wheat genome, with 9.09Mb between adjacent markers. Characteristic of recombination rates in different chromosomal regions was discussed. In addition, markers with multiple sites were aligned to homoeologous sites with a consistent order, confirming that a collinearity existed among A, B and D subgenomes. This study facilitates the integration of physical and genetical information of molecular markers, which could be of value for use in genetics and genomics research such as gene/QTL map-based cloning and marker-assisted selection.