Prevalence of amblyopia among secondary school students in Calabar, south-south Nigeria

To determine the prevalence of amblyopia among secondary school students in Calabar metropolis

It was a cross-sectional study with subjects recruited by multi-stage simple random technique. A total of 1,241 students were eligible of which 1,175 were available for vision screening with Snellen's chart. Students whose visual acuities (VA) were <6/9 in at least one eye met the inclusion criterion for refraction. While those with visual acuities >6/9 in either eye were considered emmetropic. History, ocular alignments, anterior and posterior segment examinations were carried out. Students with best-corrected VA<6/9 in either of the eyes with no identifiable pathology were considered amblyopic. Data analysis was by SPSS 15.0 (2008)

Of the screened students, there were 535 males and 640 females (chi2 = 16.439, P=0.088). The age range was 9-21 years. One thousand nine hundred and four (93.1%) had VA6/9 in both eyes (i.e. 6/9 in each eye tested separately). Of the 81(6.9%) with VA 6/9 who meant the criterion for refraction, 61 (5.2%) were refracted to at least 6/9 in both eyes. The amblyopia prevalence was 0.3% (95% confidence interval [CI], 0.27 - 0.35) with no sex (P-value = 0.088) effects but showed statistical significance with age (chi-square, chi2 = 140.954, P-value = 0.000)

The prevalence of amblyopia in this study is relatively low compared to otherAfrican and non-African studies.