Convergence insufficiency in school children in Spain

Abstract

Purpose : Convergence insufficiency is the most common binocular vision disorder but there is not much data available on its frequency. We performed a prospective cross-sectional study to determine the prevalence of convergence insufficiency at school age.

Methods : Three schools in the Madrid region of Spain participated in the study. We examined a total of 450 children from October 2019 to February 2020: 151 1^st grade (mean age 6.45 ± 0.38), 190 6^th grade (mean age 11.55 ± 0.44) and 109 8^th grade (mean age 13.61 ± 0.48). 79.9% were males and 20.1% females. The inclusion criteria was of children enrolled in 1^st, 6^th, and 8^th school grades, and the exclusion criteria was having any kind of ocular or systemic pathology that could interfere with ocular function, and mentally handicapped children. 3 children in total were excluded. Clinical evaluation: visual acuity, retinoscopy and binocular vision tests were performed, including near and far cover test (CT), near point of convergence (NPC) and Base In (BI) and Base Out (BO) vergences, measured with prism bar. We defined Convergence Insufficiency (CI) as having: BO break or blur point ≤ 15Δ or failing Sheard's criterion; break point of NPC ≥ 6 cm; and difference between near and far foria ≥ 4Δ.

Results : 5 children had strabismus (1.12 %). 4 esotropia and 1 exotropia. The prevalence of CI was 2.0% in 1^st grade; 4.80% in 6^th grade and 4.60% in 8^th grade. The difference of frequency between groups was not significant (X² p= 0.37). There was a 23.10% of 1^st grade children with a receded NPC; 40.64 % of 6^th grade and 34.26 % of 8^th grade. BO vergences ≤ 15 DP was found in 17.68% 1^st grade children, in 26.7% of 6^th grade and in 24.1% of 8^th grade. Difference between near and far foria ≥ 4 Δ was found in 11.60% children of 1^st grade, 16.6% of 6^th grade and 17.6% 8^th grade. Only NPC was found to be significantly different between groups (X² p= 0.003). 50.2% of all children didn't have any of the signs. 32.1% had just one sign, 13.8% had two signs and 3.8% had the three signs.

Conclusions : The convergence insufficiency prevalence found in school children in Spain seems to be of similar extent as in other studies, and did not vary between school grades.

This is a 2021 ARVO Annual Meeting abstract.