Refractive Error and Visual Impairment Among School Children: Result of a South-Eastern Nigerian Regional Survey

Prevalence and Causes of Blindness and Visual Impairment Among Nigerian Children: A Systematic Review

Background

Low/middle-income countries have the highest burden of blindeness and visual impairment, which directly affects the children and indirectly affects their community. Furthermore, the number of blind years suffered by children with low vision or blindness creates a self-perpetuating ripple effect on their development, health and the socio-economic development of their communities. This systematic review aims to interrogate the existing evidence on the prevalence and causes of blindness and visual impairment in Nigerian children to provide evidence to drive health policy.

Methods

This was a systematic review without meta-analysis (SwiM) using a narrative synthesis of the evidence reported using the PRISMA guidelines. All primary cross-sectional studies (in English) reporting the prevalence and causes of visual impairment among Nigerian children under 20 years old between 2003 and 2022 were included in this review. PUBMED, AJOL, BASE and ProQuest databases were searched for eligible studies between 6 June and 15 July 2023. The quality of the included studies was assessed using the AXIS tool. Results were extracted and summarised using descriptive statistics. Visual impairment and blindness using the presenting visual acuity in the better eye were reported using the WHO classification.

Results

Seventeen studies, involving 16,924 children from 13 states across five geo-political zones in Nigeria, were included in the final analysis of this review. The prevalence of visual impairment was 3.9%, 2.7% and 0.3% for mild, moderate and severe visual impairments, respectively, due to ametropia, cataracts, glaucoma, etc. The prevalence of blindness was 0.2% due to cataracts, corneal scars and optic atrophy.

Conclusion

Blindness and visual impairment is still a significant clinical and public health burden among Nigerian children. Hence, there is still a need for clinicians, especially opthalmologists, public health specialists, policy-makers, and other relevant stakeholders to intensify efforts towards the prevention and control of this burden.

Systematic review and meta-analysis of myopia prevalence in African school children

Purpose

Increased prevalence of myopia is a major public health challenge worldwide, including in Africa. While previous studies have shown an increasing prevalence in Africa, there is no collective review of evidence on the magnitude of myopia in African school children. Hence, this study reviews the evidence and provides a meta-analysis of the prevalence of myopia in African school children.

Methods

This review was conducted using the 2020 Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Five computerized bibliographic databases, PUBMED, Scopus, Web of Science, ProQuest, and Africa Index Medicus were searched for published studies on the prevalence of myopia in Africa from 1 January 2000 to 18 August 2021. Studies were assessed for methodological quality. Data were gathered by gender, age and refraction technique and standardized to the definition of myopia as refractive error ≥ 0.50 diopter. A meta-analysis was conducted to estimate the prevalence. Significant heterogeneity was detected among the various studies (I² >50%), hence a random effect model was used, and sensitivity analysis was performed to examine the effects of outliers.

Results

We included data from 24 quality assessed studies, covering 36,395 African children. The overall crude prevalence of myopia over the last two decades is 4.7% (95% CI, 3.9–5.7) in African children. Although the prevalence of myopia was slightly higher in females (5.3%, 95%CI: 4.1, 6.5) than in males (3.7%, 95% CI, 2.6–4.7; p = 0.297) and higher in older [12–18 years 5.1% (95% CI, 3.8–6.3) than younger children (aged 5–11 years, 3.4%, 95% CI, 2.5–4.4; p = 0.091), the differences were not significant. There was a significantly lower prevalence of myopia with cycloplegic compared with non-cycloplegic refraction [4.2%, 95%CI: 3.3, 5.1 versus 6.4%, 95%CI: 4.4, 8.4; p = 0.046].

Conclusions

Our results showed that myopia affects about one in twenty African schoolchildren, and it is overestimated in non-cycloplegic refraction. Clinical interventions to reduce the prevalence of myopia in the region should target females, and school children who are aged 12–18 years.