About the Author(s)

Irene Langeggen Email symbol
Department of Optometry, Radiography and Light Design, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway

Kenechukwu Ofochebe symbol
Department of Optometry, Radiography and Light Design, Faculty of Health and Social Sciences, University of South-Eastern Norway, Kongsberg, Norway


Langeggen I, Ofochebe K. Visual impairments amongst preschool and school attendees: A scoping review of vision school screening in Nigeria and Kenya. Afr Vision Eye Health. 2022;81(1), a711. https://doi.org/10.4102/aveh.v81i1.711

Review Article

Visual impairments amongst preschool and school attendees: A scoping review of vision school screening in Nigeria and Kenya

Irene Langeggen, Kenechukwu Ofochebe

Received: 06 Oct. 2021; Accepted: 12 May 2022; Published: 23 Aug. 2022

Copyright: © 2022. The Author(s). Licensee: AOSIS.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background: The United Nations Convention on the Rights of the Child emphasises the importance of quality education and good health. Vision problems affect the academic performance of schoolchildren in developing and under-resourced countries. The most prevalent vision problem amongst children is uncorrected refractive errors (URE).

Aim: To gain knowledge about vision problems and visual impairments (VI) through school vision screening amongst children in Kenya and Nigeria.

Method: A scoping review of online databases (Web of Science and PubMed) and one African registry (African Journals Online) for articles from January 2011 until April 2021 was conducted. The authors included 26 articles of the 439 screened.

Results: The literature revealed inconsistencies in how VI was defined. The main cause of vision problems is URE. Furthermore, there is a lack of systematic school vision screening tools and programmes.

Conclusion: Efficient eye care services to schoolchildren aged 3–18 years in Kenya and Nigeria must involve multiple disciplinary interventions and governmental responsibility. Collaboration models between public and private health sectors, nongovernmental organisations and families are necessary to prevent VI amongst children. Better vision enhances school performance.

Keywords: children’s rights; visual school screening; visual impairments; refractive errors; multidisciplinary healthcare.


Child eye health and prevalence of visual impairments (VI) in children remain important public health issues, especially in low- and middle-income countries. The consequences of not curbing VI can affect eye healthcare, quality of education, social participation and economic productivity.1 The United Nations Convention on the Rights of the Child is an important official human rights convention that provides a mandate for communities, governments and civil societies to improve child eye health.2 The United Nations Sustainable Development Goals (SDGs) also emphasise no poverty, good health and well-being, quality education, zero hunger, clean water and sanitation, gender equality, good jobs and economic growth, reduced inequality and partnerships for equality.3 Promotion and improvement of visual health for children will contribute to the objectives of the SDGs.4 Primary education plays a significant role in the economic growth and development of any country. An educated population holds the potential to create a better society, including democracy, equity and greater well-being.1 In Nigeria, the population of 207 million has a mean age of 18 years.2 The mean age amongst 57 million inhabitants of Kenya is 20 years.5 Therefore, these two countries have a necessity to improve vision eye care, which influences education and quality of life.

The challenge is to establish eye healthcare programmes that will meet the basic needs of schoolchildren.6,7 The World Health Organization (WHO) defines VI as presenting visual acuity (VA) less than 6/12 in the better eye.8 Refractive errors (RE)9 prevent clear imaging on the retina.10 The effect of RE is determined by measuring VA. Uncorrected refractive errors (URE) are regarded as the most common cause of VI and blindness globally.11 The results of VI have adverse effects on health, socio-economic development and quality of life, and 90% of people with URE live in developing countries.12 Visual impairment is ranked in sixth position in the global load of disease relating to disability-adjusted life years and increased mortality, and the numbers of people with VI are growing because of an increase of population.13 About 18.93 million children in the age group of 0–14 years were estimated to have VI in a population of 1.848 billion.14 Thus, a great deal of interest and attention should be focused on the younger generation towards enhancing good quality of life.15

Costs to build the necessary infrastructure and train personnel to deliver the services needed to correct VI over five years are estimated at around $20 billion.16 Only one university in Kenya graduates optometrists, Masinde Muliro University of Science and Technology,17 whilst six education alternatives are available in Nigeria.18 The ratio for optometry educational programmes to population is similar in the two countries, that is, one educational programme per 50 million people (optometrists are educated healthcare personnel who are trained in outpatient care).19

This paper presents a scoping review20 to gain knowledge about school vision screening amongst preschoolers and schoolchildren in Kenya and Nigeria and their vision problems.21,22 The authors searched for a model to learn from in relation to care for visual health amongst young people.

Scoping review

Two online databases (Web of Science and PubMed) and one African registry (African Journal Online [AJOL]) were searched for articles published from January 2011 until April 2021. The search revealed 439 articles, and 26 of those that were included are listed in Table 1. The search process is illustrated in Figure 1. The reason for choosing the last 10 years of publications was to include newer studies that were accomplished closer to the current date. AJOL’s filters were used on date from newer to older articles and relevance of articles. Included articles in this search are in relation to relevance. Search words and terms were ‘school visual screening, visual problems, refractive errors’. Limitations for the search were age, namely 3–18 years of age, and search words like ‘children’, ‘adolescence’ and ‘pupils’ were used in addition to age limits. The scoping review was limited to Kenya and Nigeria. No profession was specified in the search since visual evaluation at community health level is performed by different professions. The two authors screened titles and abstracts for the words of interest. Articles of interest included screening methods and learned lessons or recommendations (see Table 1). This review presents vision problems and VI in young school-aged populations within the borders of Kenya and Nigeria. The scoping review followed PRISMA scoping guidelines.20

TABLE 1: Summary of articles included in scoping review.
FIGURE 1: PRISMA flow-chart.

Ethical considerations

This article followed all ethical standards for research without direct contact with human or animal subjects.


The search revealed 439 articles, where 26 articles met the inclusion criteria. The PRISMA diagram (Figure 1) presents details of the evaluation process.23 African Journals Online (AJOL) search filters were used for relevance or date,24 and the number of articles from AJOL exceeded those from the other databases. In Table 1, the articles are presented with author, year of publication, country, population size and gender, age of examined children, visual acuity defining VI in study, visual findings of interest, refractive error causing VI, specific clinical procedures and the main outcome or recommendation of studies. The outcome is presented with letters such as ‘A’, that is, recommending visual screening amongst children; ‘B’, recommending parents and teachers be involved in avoiding unnecessary VI amongst children; and ‘C’, recommending obligatory visual evaluation of children’s vision and eye health. The included 26 articles comprise three studies from Kenya with a study population of 24 879 (including two cohorts),25 and 23 studies from Nigeria with a study population of 24 344.

Visual impairment

Visual impairments were defined to be equal to or below VA of 6/9.5 in 10 studies,30,34,35,37,39,40,42,43,48 seven studies9,22,34,35,36,37,38 presented VA equal to or below 6/12 and two presented VA below 6/18.25,35 Visual acuity was not recorded in seven studies (see Table 1). Pinhole VA, which is possibly a better VA estimate, was seldom tested.34,39 Refractive errors causing VI varied from 0.7%39 to 81%.35 Visual acuity amongst preschoolers requires a visual acuity test valid for preschoolers such as LEA symbols and Tumbling E.36,40 Table 1 presents the different methods or procedures used to measure VA.

Ocular findings

Refraction results were given by retinoscopy27,29 or cycloplegic procedure,12,27 or no method was mentioned (see Table 1). A few studies included amblyopia33,38 or binocular vision evaluations.26,31,41 Ocular health27,30,31,34,41,42 and colour vision26,30 were also evaluated. Ocular axial dimensions (see Table 1)43 were estimated in relation to prevalence of myopia. Prevalence of ocular injuries was 7.93% and education of children remains necessary to prevent ocular hazards.44

Sustainable eye healthcare

Three different protocols for school screening were mentioned: refractive error in school-aged children (RESC),29 convergence insufficiency symptom survey (CISS)31 and the Peek Acuity screening app.25 School vision screening programmes were recommended by 20 of 26 studies (see section C in Table 1). Teachers can perform and be active in school vision screening.32,39,41 Optometrists were only mentioned as active participants in school vision screenings in one study.26 None of the studies were performed in schools or communities with an established visual healthcare programme for children.

The main outcome of the studies were to introduce regular eye health examinations12,27,29,31,37,45 through eye healthcare programmes (see Table 1, section C). Uncorrected RE influences education and it is thus important to provide refractions and good vision with spectacles, for example, to all age groups.27,30,34,37,42


The scoping review revealed that clinical procedures for evaluation of vision amongst children aged 3–18 years were inconsistent or even missing. Refractive errors amongst schoolchildren can vary significantly based on gender, age group, school type and socio-economic status (SES) of the parents or guardians.27 The scoping review revealed the differences in defined VI in relation to VA. Refractive errors are the main cause of VI. The results from the scoping review form the basis for a potential recommendation to official stakeholders to enhance children’s visual eye care.

Visual impairment

Visual acuity procedures presented in the articles indicate that VA at distance is measured by different clinical procedures (see Table 1). There is no defined recommendation of which acuity chart to use whilst in school screening settings.46 The WHO definition of VI as VA equal or below 6/12 was used by six studies.9,22,34,35,36,37,38 The argument of VI being better than the WHO definition is probably to detect lower refractive errors. None of the articles discussed why the definition of VI was different from WHO recommendation.8

Refractive errors

The Ophthalmic Division in Kenya has improved the healthcare awareness on ocular disorders like URE.28 This improves early detection and management and provides patients with spectacles to regain their sight at an early age. To optimise learning, there is a need to prioritise regular vision school screening as part of primary eye care in Nigeria.47 Kenya and Nigeria require more advanced awareness and education to the public through health professionals such as optometrists to fight unnecessary blindness and VI. In addition, comprehensive eye assessment to determine RE and type of spectacles is also required.

Many children in the study populations had URE as the main cause of VI. Visual improvement was achieved by wearing spectacles. One study suggested that RE is more likely to affect children who have parents of high SES or middle-class status than children with low-SES parents. The findings are linked to the fact that those in private schools were two times more likely to have RE than those in public schools. Children from high- and medium-income families are mainly enrolled in private schools rather than public schools.27 The study in the West District of Kenya35 indicates that VI usually manifests amongst 11–15 year-old adolescents, and differences in the economic characteristics of the children’s parents can contribute to VI cases. It is expected that good economic status facilitates access and affordability of eye care services that reduce the problem of VI and blindness. Parents from public schools had lower economic status and could not afford the costs of acquiring spectacles for their children. Meanwhile, parents from private schools had better economic status and hence were more likely to acquire spectacles. The pupils with RE who could afford spectacles had corrected VA > 6/18 and thus were not subjected to further examination.35 Thus, there is a need for enforcement of school health policies on vision screening before enrolment as well as annual school eye examination to enhance early VI detention and management.35

In South-East Nigeria, Onitsha Nigeria children in this urban environment mostly engage in indoor rather than outdoor activities,12 including higher usage of computers, smartphones and video games, which contributed to an increased prevalence of RE. However, in rural areas, increased outdoor activities and exposure to high light intensity are quite common amongst the dwellers, which have been suggested to be the main factors reducing prevalence of RE in rural areas.48 Myopia was found to increase with age. It could possibly be because the age group is mostly in Grades 5 and 6, which are the grades for preparing and writing entrance examinations to high school in Nigeria, leading to increased academic demand and near work activities.12

Sustainable eye healthcare

Ocular findings, including binocular anomalies, amblyopia and hazards, imply other causes of VI than URE. Knowledge of normal ocular axial dimensions is important to establish school screening programmes with clear procedures and pass or fail determinants. The WHO has established a definition of VI,8 but this literature review presents several definitions of VA in relation to VI. Worldwide there are several clinical guidelines to evaluate visual status amongst children. The interdisciplinary team must be involved to achieve a cost-effective school vision screening programme.46

A range of strategies are required to control visual loss in children and improve school eye health in Nigeria and Kenya. The main purpose of health promotion is to promote safe and healthy behaviours through policies and other modules of health education strategy.1 The aim of primary health prevention is to reduce the occurrence of cases of potentially blinding conditions. Secondary prevention deals with interventions which can prevent blindness and VI consequences, such as early detection and treatment of corneal ulcers in children and lid surgery for an affected person with trachoma. Tertiary prevention involves treatment which resorts to functions such as spectacle correction of URE and interventions to improve function where sight cannot be restored, such as low vision services and rehabilitation.1

Yasmin et al. argue that children should be offered general vision screening when they enter and leave primary school and when they graduate high school. The main idea is to conduct eye health screening for children and teachers in school and to refer those who need further management for eye examination, refraction and dispensing of spectacles. Successful school eye health programmes should include the support and engagement of the local education authorities and increasing awareness about a healthy school environment amongst children, teachers and communities. Also, it is necessary to make schools inclusive for children with VI so they can learn together with normal children.49,50

A study in Nepal7 identified established models for school screening programmes that can be adopted in Nigeria and Kenya. One model is the teacher-oriented approach, whereby the teacher through continuous education is empowered to conduct initial visual tests. The second approach is the ‘eye care team’, where optometrists conduct VS, and VI children with URE are referred to nearby hospitals for follow-up. The third approach is a combination of the first and second models that also includes health promotion education of children and next of kin and optimal utilisation of spectacles. The third model also includes an official strategy and structure to enhance visual care amongst children.7 The integration of eye health into comprehensive school health programmes will help to identify children with VI. This will enable eye health education to reach many children and their families through a child-to-child approach.

Vision affects the way a human being relates to and integrates in society, and vision influences education, employment, mental health, child development and operative capacity of older people. The effects of VI in developing countries challenge these countries to achieve the United Nations SDGs, which include no poverty, quality education, decent work and economic growth and reduced inequalities.13,21

The Ministries of Health and Education are key developers of policy and crucial partners to school eye health initiatives with the purpose of scaling up activities at the national level. The development of school screening guidelines is crucial to integrate strategies for early detection and intervention in children using the ‘promoting healthy schools’ framework.1 Eyecare includes correction of RE by use of quality spectacles that are acceptable, durable, comfortable and affordable. Children with VI need further optometric and ophthalmological care and a patient path including identification, referral and treatment of potentially visual impairing conditions.1


This scoping review revealed some inconsistency in defining VI and visual healthcare or eye service amongst preschool and schoolchildren in Kenya and Nigeria. Refractive errors account for VI, which is possible to avoid through refraction and spectacles amongst children of 3–18 years of age. Interventions are required due to the rapid growth of the population. In the future, an eye healthcare model or programme with optometric competencies and following a systematic approach must aim at avoiding unnecessary refractive errors and providing good vision. It is legitimate to conclude that good visual health is likely to reduce productivity loss amongst future generations.


The authors are grateful for the initiative and support to write this article by Kesi Naidoo, African Eye Institute, Durban, South-Africa.

Competing interests

The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.

Authors’ contributions

I.L. and K.O. have written in collaboration and with equal input to the article.

Funding information

The Norwegian Agency for Exchange Cooperation (NOREC) supports the EYE-FX project, from which both authors gained interest in optometry and eye health education.

Data availability

Data supporting the findings of this study are available from the corresponding author, I.L., on request.


The views and opinions expressed in this article are those of the author(s) and do not necessarily reflect the official policy or position of any affiliated agency of the authors.


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