| Objective To investigate the epidemiology of the anisometropia of children in 3—15 years old, and to evaluate the effects of various types of anisomtropia on visual acuities and sterreopsis, we collected the information of the anisometropia and correlation factors.Methods The data of the subject was sampled from the materials of population-based and cluster sampling of children in the project The Epidemio logic Survey of Prevalence of Strabismus, Amblyopia and Refractive error of 1~15-year Children in Tianjin (ESPSARC, Tianjin). The subject included 6001 children in 3-15 years old. The children who refused to be examined and were unwilling to cooperate with the examiners were excluded. Finally there were only 5942 children according to our standards.Before the formal examination, survey workers were trained with knowledge of the significance, purpose, methods and detailed steps of the survey. They were familiarized with proper instructions of completing different types of tables and lists, the meanings and contents of various variables in the unified survey tables, the inspectoscopes and examination flow. Referring to some literatures, we established the corresponding definitions and standards and conducted the pilot study.The examiners enumerated all sampled children and recorded the results. The self-designed 《 Table for Survey of Strabismus, Amblyopia and Refractive error of Children》 was used in the questionnaire and examination of the subject. The data included general material (name, sex, age, nationality, address, school, grade, classand names of parents or guardians), the history of eye-related diseases of parents, mother's age and pregnancy history, birth conditions of the child (birth weight, delivery mode) and child's past history of eye diseases, etc. Ophthalmological examinations included uncorrected, presenting and corrected visual acuity, cover-uncover test, ocular movement, stereoscopic visual acuity, retinal correspon -dence, blepharon, conjunctiva, corneas, pupils, lens, the refraction before and after cycloplegia, vitreous and retina, etc.The fieldworkers were composed of ophthalmologists, doctor assistants and optometrist. The ophthalmologists took charge of the fieldwork supervisors to guarantee the survey quality. The data was examined, verified and recorded by special persons. The data input was done twice to ensure accuracy.Because of the non-normal distribution of the data, nonparametric tests were used. The %2 test was used for comparisons of categorical data between groups;The Krushal-Wallis and Mann-Whitney tests were used for comparisons of continuous measures between groups;The two-sample Kolmogorov -Smimov test was used to compare distribution;Logistic regression was used to evaluate the correlation between anisometropia and age, sex, spherical power and cylindrical power. PO.05 was taken as representing a significant difference.Results1. In the study, there were boys 3032 (50.5%) and girls 2969 (9.5%). The prevalence rates of anisometropia, in terms of mean spherical equivalent (MSE) of at least 1.0D and 2.0D, were 10.51% and 2.95% respectively, including 7.5% in the mild anisometropia, 1.8% in the moderate anisometropia, and 1.2% in the severe anisometropia. In the four kinds of the anisometropia, the prevalence rates of anisometropia were the most in the cylindrical hyperopia (19.9%), least in thespherical myopia (10.7 % ) .At the same time, 10.9 % in the spherical hyperopia and 15.8% in the cylindrical myopia.2. In the myopia, the right eye is easier to have anisometropia than left eye. There were 54% children who had higher refractive power in the right eye than that in the left eye. The MSE in the right eye (-2.9615D) is larger than that in the left eye (-2.0658D). There are significant differences in the refractive state between the two eyes (Wilcoxon Signed Ranks Test, z=36.85, p<0.05).3. There are significant differences in the prevalence and severity of anisometropia between ages. The prevalence and severity of anisometropia increased with age, which just reached statistical significance (%2—134.665, p<0.005).4. The parameters of the Logistic regression model described the association between anisometropia and the exanplanatory variables of age, sex, spherical power and cylindrical power. Sex is not closely associated with anisometropia. Without the alteration of the other variables, the OR increased 1.249~2.868 times by enchancing one rank of the exanplanatory variable of cylindrical power, 1.141-—1.588 times of the exanplanatory variable of spherical power, and 1.012~ 1.120 times of the exanplanatory variable of age. The exanplanatory variable of cylindrical power was the most meaningful parameter in the occurrence of the anisometropia, and the regressive coefficience of cylindrical power (0.224~ 1.054) was larger than those of spherical power (O.133~O.53O) and age (0.095—0.113).5. In the four kinds of the anisometropia, there was the same trend: (1) sterreopsis descending;(2) finalvisual acuity descending;(3) interoculat acuity difference ascending. When CHA >1.00D~2.00D, SMA > -2.00D~-3.00D, CMA > -1.00D --2.00D, SHA>1.00D~2.00D, the incidence of amblyopia and abnormal stereopsis were significantly increased, and the level of stereopsis decreased.Conclusion1. The prevalence rates of anisometropia, in terms of mean spherical equivalent (MSE) of at least 1.0D and 2.0D, were 10.51% and 2.95% respectively.2. In the myopia, the rght eye is easier to have anisometropia than the left eye.3. Age, spherical power and cylindrical power were independent variables associated with anisometropia, but sex was not.4. In the four kinds of the anisometropia, there was the same trend: (1) sterreopsis descending;(2) final visual acuity descending;(3) interoculat acuity difference ascending. The incidence of amblyopia and abnormal stereopsis were significantly increased, the level of stereopsis decreased. |
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