Abstract:AIM: To investigate the prevalence of convergence insufficiency(CI)of primary school children in Nanchong and to analysis its relationship with age, gender and myopia in a school screening study.
METHODS: A cross-sectional screening study was used to select students in grades three, four, and five of three primary schools in the urban area of Nanchong from April to June in 2019. They were all performed relevant eye examinations, including slit lamp, fundus examination, vision acuity, refraction, distance and near heterophoria with alternate cover test, near point of convergence(NPC), and near positive and negative fusional vergences. A questionnaire of convergence insufficiency symptom survey(CISS-15)was performed for each participant, and a score of ≥21 was considered as a positive symptom.
RESULTS: Of the 4123 students, 2876 students participated in the study. And the data was analyzed using 2571 participants. The average age of the participants was 9.33±0.02(7 to 13)years. The prevalence of CI was 12.4%, and analysis of variance showed no gender difference(χ2=0.479, P=0.489). The CI prevalence among primary third, fourth, and fifth grade students were 12.4%, 11.3% and 13.5%, respectively, and there was no statistically significant difference in the prevalence of CI between grades(χ2=1.97, P=0.374). The prevalence of myopia among students in the third, fourth and fifth grades was 15.1%, 24.0% and 34.5%, respectively, and the difference in the prevalence of myopia between grades was statistically significant(χ2=86.47, P<0.01). Of the 641 myopic students, 240(37.4%)were diagnosed as CI, while the CI prevalence of non-myopic students was 4.15%. The difference between the two groups was statistically significant(χ2=489.54, P<0.01).
CONCLUSION: This study shows that the overall prevalence of convergence insufficiency of primary school students in Nanchong was 12.4%, which was higher than most previous studies. The prevalence of convergence insufficiency in myopic students was significantly higher than that in non-myopic students. There was no statistical difference in the prevalence of convergence insufficiency between different grades and genders.
