Study on the degree and axis of astigmatism in myopic primary and secondary school students

AIM: To study the degree of astigmatism, axial distribution and axial symmetry pattern of binocular astigmatism in primary and secondary school students aged 7-18 years with myopia.METHODS:A total of 239 cases(478 eyes)of primary and secondary school students aged 7-18 years who underwent keratoplasty for myopia correction at the Fifth Affiliated Hospital of Zhengzhou University from 2020 to 2022 were randomly selected, and optometry was performed under ciliary muscle paralysis and was statistically analyzed.RESULTS:Astigmatism degree: 0.25 to 1.00 D accounted for 78.5%, 1.25 to 2.00 D accounted for 17.1%, and >2.00 D accounted for 4.4%. The axial distribution of astigmatism: 86.6% was astigmatism with the rule, 5.9% was astigmatism against the rule, and 7.5% was oblique astigmatism; both genders and different astigmatism degrees were dominated by astigmatism with the rule, and there were differences with the other two axes(both P<0.05). Axial symmetry pattern of astigmatism: the median axial difference in astigmatism between the direct symmetry model and the mirror symmetry model was 7° and 10°, respectively, with no statistical significance in both models(P=0.158), and there was no difference between the two in gender, degree of astigmatism, and axial distribution of astigmatism, but in the age group of 7-12 years old, the difference between the axial astigmatism of the direct symmetry model and the mirror symmetry model was statistically significant(P=0.027).CONCLUSION:The axial distribution of binocular astigmatism in myopic primary and middle school students is mostly astigmatism with the rule; the degree of astigmatism is more common from 0.25 to 1.0 D; however, there is no tendency for axial symmetry pattern of astigmatism.