Prevalence of convergence insufficiency among secondary school students in Khartoum, Sudan

BACKGROUND: Few studies have examined the prevalence of convergence insufficiency (CI) in a school-based population in Sudan. This study sought to determine the prevalence of CI and its related clinical characteristics among Sudanese secondary school students. MATERIALS AND METHODS: A descriptive cross-sectional survey was conducted in Central Khartoum North, Sudan, in the academic year 2013/2014. A total of 4211 secondary school students, with a mean age of 15.5 ± 2.5 years, underwent complete eye examination, and were screened for symptoms associated with near work. Near and distance heterophoria was measured with the alternate cover test using a prism bar; near point of convergence (NPC) and positive fusional vergence (PFV) at near were determined. RESULTS: Of the 4211 students screened, 329 (7.8%) were diagnosed with CI. Of these, 173 (52.6%) students were male and 156 (47.4%) were female; there was no significant relationship between sex and CI (P > 0.05). Standard schools had a higher prevalence of CI (43%) than geographic schools (36%) and there was a significant association between CI and the type of school (P < 0.05). In most of the students (78.42%), CI was due to both remote NPC and decreased PFV; in 20.36% of the students, CI was due to remote NPC only, and in very few students (1.22%), it was due to decreased PFV only. CONCLUSIONS: These findings suggest that CI is prevalent in the secondary school population in Central Khartoum North, Sudan.