Prevalence of Convergence Insufficiency (CI) Among Secondary School Students in Southwest Nigeria

Paediatric Ophthamology & Strabismus

Abstract

Background: Convergence insufficiency (CI) is a binocular vision disorder characterized by exophoria greater at near than at distance, a receded near point of convergence, and reduced positive fusional vergence (convergence amplitudes) at near.1,2,3 Convergence  insufficiency (CI) is a common binocular vision disorder affecting 4-6% of the population. 1,4,5 Some studies have reported a  prevalence as high as 33% with an average of about 5%.6 Convergence insufficiency has been shown to have a negative impact on the quality of life and school performance in schoolage children.7 The child’s academic performance in secondary school is an important  criterion in determining progress and choice of course of study into a tertiary institution, this may have life-long effects in determining  the socioeconomic status and well-being as a full-grown adult. The purpose of this study is to determine the prevalence of convergence insufficiency (CI) among secondary school students in southwest Nigeria.

Methods: This was a descriptive cross-sectional study conducted among 8-21year old students in September/March 2016. A multistage  sampling was used to pick a representative sample of students in public senior and junior secondary schools in Ido Local  Government Area Ibadan. Eligible students with Visual acuity > 6/9 in both eyes, normal ocular findings with no strabismic or non strabismic binocular disorders were recruited. NPC was measured with RAF rule line. Positive fusional vergence and heterophoria measurements were done using prism bars and Von Graefe method respectively. Students with receded NPC > 7.5 cm break or > 10.5 cm recovery, Exophoria at near > 4 “ greater than far, and insufficient Positive fusional vergence were classified as having CI according  to the Convergence insufficiency Reading Study group (CIRS)classification.