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. 2022 Aug 18;17(8):e0271313. doi: 10.1371/journal.pone.0271313

Prevalence of visual impairment due to refractive error among children and adolescents in Ethiopia: A systematic review and meta-analysis

Daniel Atlaw 1,*, Zerihun Shiferaw 1, Biniyam Sahiledengele 2, Sisay Degno 3, Ayele Mamo 4, Demisu Zenbaba 2, Habtamu Gezahegn 1, Fikreab Desta 2, Wogene Negash 5, Tesfaye Assefa 5, Mujib Abdela 6, Abbul Hasano 1, Gashaw Walle 7, Chala Kene 6, Degefa Gomora 6, Vijay Kumar Chattu 8,9,10
Editor: Consolato M Sergi11
PMCID: PMC9387832  PMID: 35980970

Abstract

Introduction

Globally, the prevalence of refractive error was 12%, and visual impairment due to refractive error was 2.1%. In sub-Saharan Africa, the prevalence of refractive error and visual impairment due to refractive error was 12.6% and 3.4%, respectively. In Ethiopia, the prevalence of visual impairment due to refractive error varies from 2.5% in the Gurage zone to 12.3% in Hawassa city. Hence, this Meta-analysis aimed to summarize the pooled prevalence of visual impairment due to refractive error in Ethiopia.

Methods

A systematic search of the literature was conducted by the authors to identify all relevant primary studies. All articles on the prevalence of visual impairment due to refractive error in Ethiopia were identified through a literature search. The databases used to search for studies were PubMed, Science Direct, POPLINE, HENARI, Google Scholar, and grey literature was searched on Google until December 15, 2021. In this meta-analysis, the presence of publication bias was evaluated using funnel plots and Begg’s tests at a significance level of less than 0.05. The sensitivity analysis was conducted to check for a single study’s effect on the overall prevalence of refractive error.

Result

About 1664 studies were retrieved from initial electronic searches using international databases and google searches. A total number of 20,088 children and adolescents were included in this meta-analysis. The pooled prevalence of visual impairment due to refractive error in Ethiopia using the random effects model was estimated to be 6% (95% CI, 5–7) with a significant level of heterogeneity (I2 = 94.4%; p < 0.001). The pooled prevalence of visual impairment due to refractive was analyzed by subtypes, and pooled prevalence was estimated to be 4%, 5.2%, and 1% for myopia, hyperopia, and astigmatism, respectively.

Conclusion

The pooled prevalence of visual impairment due to refractive error was high in Ethiopia. About one in twenty-five Ethiopian children and adolescents are affected by visual impairment due to myopia.

Introduction

Refractive error (RE) occurs when the eye’s optical system fails to adjust to bring parallel beams of light into proper focus on the fovea [1, 2]. Refractive error includes myopia, hyperopia, astigmatism, and presbyopia. It is the most common cause of reduced visual impairment [3]. More than 43% of visual impairment is caused by uncorrected RE [4, 5], which is the second leading cause of blindness [1].

Globally the prevalence of RE was 12% [4], and visual impairment due to RE was 2.1% [6]. A review and meta-analysis conducted in India revealed the prevalence of visual impairment due to RE to be 10.8% [7]. In sub-Saharan Africa, the prevalence of refractive error and visual impairment due to RE was 12.6% and 3.4%, respectively, in 2015 [5]. In Ethiopia, the prevalence of visual impairment due to refractive error varies from 2.5% in the Gurage zone [8] to 12.3% in Hawassa city [9].

The global initiative to eliminate avoidable blindness by 2020 (VISION 2020: the Right to Sight) has included RE as one of the five priority eye diseases, following epidemiological studies highlighting the escalating estimates of RE prevalence [10, 11]. Over 80% of visual impairments are preventable; therefore, reducing avoidable visual impairment remains an important international public health goal [12].

Visual impairment impacts economic growth, home care, and rehabilitation that account for a fraction of the annual monetary cost and loss of quality-adjusted life-years that can be averted by fifteen percent if the refractive error is corrected [13–15]. In addition to the direct impact on quality-of-life visual impairment also affects the educational system by impairing reading speed, accuracy, and fluency [16].

Even if many studies were conducted in different parts of Ethiopia on visual impairment due to refractive error [2, 8, 9, 17–35], their results were varying and uneven. For instance, 1.9% in Jima [30], 11% in Gondar [20], and 7.2% in Wolkite [33]. Hence, this meta-analysis aimed to summarize Ethiopia’s pooled prevalence of visual impairment due to refractive error.

The findings from this meta-analysis will benefit health planners and concerned bodies to act on uncorrected refractive error, thereby reducing the prevalence of visual impairment due to modifiable refractive error in Ethiopia. The findings can also be used by various governmental and non-governmental organizations working in eye care to prioritize the problem of vision impairment in Ethiopia.

Methods

Study design and reporting

A review and meta-analysis were conducted to estimate the pooled prevalence of visual impairment due to refractive error in Ethiopia among children and adolescents. This review and meta-analysis were conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines [S1 Checklist].

Eligibility criteria

Individual studies done in Ethiopia to determine the prevalence of visual impairment due to refractive error among children following criteria were included in the meta-analysis.

Population

All studies that had reported the prevalence of visual impairment due to refractive error among children.

Study designs

Observational studies reporting the prevalence of visual impairment due to refractive error among children were eligible for this systematic review and meta-analysis.

Publication status

Published and unpublished articles were considered.

Year of publication

All publications reported until December 15, 2021, were considered.

Exclusion criteria

Studies that reported visual impairment but did not have a separate outcome for refractive error were excluded from the study.

The outcome of this systematic review and meta-analysis

Visual impairment due to refractive error

Visually impaired children due to amblyopia, hyperopia, and astigmatism. For visual acuity impairment, the participants in the primary study were visually impaired when their VA was 6/12 or worse in “either eye.”

Search strategy

A systematic search of the literature was conducted by the authors to identify all relevant primary Studies. All articles on the prevalence of visual impairment due to refractive error in Ethiopia were identified through a literature search. The databases used to search for studies were PubMed, Science Direct, POPLINE, HENARI, Google Scholar, and grey literature was searched on Google until December 15, 2021. The following key search terms and Medical Subject Headings [MeSH] were used “refractive” OR “amblyopia” OR “astigmatism” OR “hyperopia” AND “Children” AND “Ethiopia [MeSH]” were used separately or in combination with the Boolean operator’s terms “AND” and “OR” [S1 File]. Moreover, the reference lists of the retrieved studies were also scanned to access additional articles and screened against our eligibility criteria. Further Ethiopian university websites were used to search for unpublished articles.

Study selection

In this meta-analysis, all the searched articles were exported into the EndNote version X8 software, and subsequently, the duplicate articles were removed. Screening of retrieved article titles, abstracts, and the full text was conducted independently by two review authors (DA & ZS) based on the eligibility criteria. Afterward, full-text articles were retrieved and appraised to approve eligibility. Finally, the screened articles were compiled together by the two investigators.

Risk of bias assessment

The qualities of the included studies were assessed, and the risks for biases were refereed using the Joanna Briggs Institute (JBI) quality assessment tool for the prevalence studies. Two reviewers (DA and ZS) assessed the quality of included studies independently, and a discrepancy between the two reviewers was resolved with discussion. The evaluation tool comprises nine parameters: (1) appropriate sampling frame, (2) correct sampling technique, (3) acceptable sample size, (4) study subject and location explanation, (5) appropriate data investigation, (6) use of valid methods for the identified conditions, (7) valid measurement for all participants, (8) using appropriate statistical analysis, and (9) adequate response rate [36]. Failure to satisfy each parameter was scored as 1 if not 0. When the information provided was not satisfactory to assist in deciding on a specific item, we agreed to grade that item as 1. The risks for biases were classified as either low (total score, 0 to 2), moderate (total score, 3 or 4), or high (total score, 5 to 9) [S1 Table].

Data extraction

The selected articles were carefully reviewed, and the required information for the meta-analysis was extracted and summarized using an extraction table in Microsoft Office Excel software. The data extraction was conducted by the two authors (DA and ZS) based on prespecified headings that are agreed on by discussion. The data extraction tool consists of the name of the author (s), year of publication, year of study, professionals conducting the visual examination, region, study design, study setting, study population, sample size, prevalence, and risk of bias.

Statistical methods and analysis

The extracted data were imported into STATA version 14 software for statistical analysis. The heterogeneity among all included studies was assessed by I2 statistics and the Cochran Q test. In this meta-analysis, the tests indicate the presence of significant heterogeneity among included studies (I2 = 98.5%, P-value < 0.001). The random-effects model was used to analyze the data because the heterogeneity is high, and 22 studies were included in this meta-analysis [37, 38]. The pooled prevalence of visual impairment due to refractive error along their corresponding 95% CI was presented using a forest plot. Subgroup analyses were conducted using the region of the primary study, year of publication, year of study, study setting, sample size, eye examiners’ profession, and risk of bias. Meta-regression analysis evaluated the association between the prevalence of refractive error and publication year, study year, and sample size among the included studies. In this meta-analysis, the presence of publication bias was evaluated using funnel plots [39] and Begg’s tests at a significance level of less than 0.05. Begg’s test was selected because of the dichotomous nature of the outcome [40]. The sensitivity analysis was conducted to check for a single study’s effect on the overall prevalence of refractive error.

Results

Description of included studies

About 1664 studies were retrieved from initial electronic searches using international databases and google searches. The database included PubMed (n = 16), HENARI (n = 266), POPLINE(n = 235) Science Direct (n = 46), Scopus(n = 157), Google Scholar (n = 942), and Addis Ababa University repository (n = 2) studies. Of these, 1470 duplicates were removed, the remaining 194 articles were screened by title, and 131 articles were excluded after reading their titles. Sixty-three full-text articles remained and were further assessed for their eligibility. Finally, based on the pre-defined inclusion and exclusion criteria, a total of 22 articles were included in the meta-analysis, and data were extracted for the final analysis [Fig 1].

Fig 1. Flow diagram of systemic review and meta-analysis conducted on visual impairment due to refractive error in Ethiopia, 2021.

Fig 1

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Characteristics of the included studies

A total number of 20,088 children and adolescents were included in this meta-analysis. All included studies are cross-sectional in design. The latest article was conducted in 2020, and the earliest study was concluded in 2000. Depending on sample size, sixteen studies have a sample size greater than or equal to 500, and six studies have a sample size less than 500. Nine studies were conducted in the Amhara region, seven in the Southern Nation and Nationality Region (SNNR), three in Addis Ababa, two in Tigray, and one in the Oromia region. About fifteen were school-based, five were community-based, and two were hospital-based studies. Concerning the risk of bias among studies, the majority (16) of studies were judged to have a low risk of bias [Table 1].

Table 1. Characteristics of included studies for the pooled prevalence of visual impairment due to a refractive error in Ethiopia, 2021.

Author name Year of publication Region Study design Sample size Risk of bias Prevalence of RE Study setting Diagnosed by year of study
Zelalemet al.l [17] 2019 Amhara Cs 875 Low 0.038 Community-based Optometrist 2016
Sewunet et al. [2] 2014 Amhara Cs 420 Low 0.088 School-based Optometrist 2013
Kassa and Alene [18] 2004 Amhara Cs 1134 Low 0.076 School-based Not mentioned 2000
Weldeamanuel et al. [8] 2020 SNNP Cs 1064 Low 0.025 School-based Ophthalmologist 2017
Alem and Gebru [9] 2021 SNNP Cs 554 low 0.123 School-based Optometrist 2016
Darge et al. [19] 2017 Addis Ababa Cs 378 medium 0.05 School-based Ophthalmologist 2015
Ferede et al. [20] 2020 Amhara Cs 1289 medium 0.026 School-based Ophthalmologist 2016
Tegegne et al. [21] 2021 Amhara Cs 601 medium 0.085 School-based Optometrist 2019
Yared et al. [22] 2012 Amhara Cs 1852 low 0.049 School-based Optometrist 2010
Bezabih et al. [23] 2017 Addis Ababa Cs 718 medium 0.036 School-based Optometrist 2016
Hailuet al.l [24] 2020 Addis Ababa Cs 773 medium 0.041 School-based Ophthalmologist 2019
Mehari and Yimer [25] 2012 SNNP Cs 4238 medium 0.063 School-based Optometrist 2010
Kedir and Girma [27] 2010 SNNP Cs 570 low 0.035 Community-based Not mentioned 2018
Dhanesha et al. [28] 2018 Tigray Cs 1137 low 0.058 School-based Not mentioned 2012
Mehari [35] 2014 SNNP Cs 735 low 0.053 Hospital-based Ophthalmologist 2003
Shaffi and Bejiga [34] 2005 SNNP Cs 826 low 0.063 Community-based Not mentioned 2003
Demissie and Demissie [31] 2014 Oromia Cs 341 low 0.059 Hospital-based Optometrist 2018
Belete et al.[32] 2016 Amhara Cs 495 low 0.11 School-based Optometrist 2016
Gessese and Teshome [33] 2020 SNNP Cs 1271 low 0.072 School-based Optometrist 2016
Demissie and Solomon [30] 2011 Oromia Cs 112 low 0.053 School-based Ophthalmologist 2010
Asferaw et al. [29] 2017 Oromia Cs 104 low 0.019 Community-based Not mentioned 2015
Merrieet et al. [26] 2021 Amhara Cs 601 low 0.065 Community-based Optometrist 2017
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Cs = cross-sectional

The publication biases

The presence of publication bias was evaluated using funnel plots and Begg’s tests at a significance level of less than 0.05. The findings revealed that publication bias was not significant for the studies on the prevalence of refractive error in Ethiopia (p = 0.096) [Fig 2].

Fig 2. Showing the publication bias status of studies included for meta-analysis on visual impairment due to refractive error in Ethiopia,2021.

Fig 2

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Sensitivity analysis

The presence of a single study effect on the pooled prevalence of refractive error was tested using meta-influence analysis and revealed that there is no study significantly affecting the pooled prevalence of refractive error in Ethiopia [Fig 3].

Fig 3. Showing the sensitivity analysis of meta-analysis on visual impairment due to refractive error in Ethiopia, 2021.

Fig 3

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Prevalence of refractive error in Ethiopia

The pooled prevalence of refractive error in Ethiopia using the random effect model was estimated to be 6% (95% CI, 5–7) with a significant level of heterogeneity (I2 = 94.4%; p < 0.001) [Fig 4].

Fig 4. Funnel plot showing the pooled prevalence of visual impairment due to refractive error in Ethiopia, 2021.

Fig 4

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The pooled prevalence of visual impairment due to refractive was analyzed by subtypes, and pooled prevalence was estimated to be 4% [Fig 5], 2% [Fig 6], and 1% [Fig 7] for myopia, astigmatism, and hyperopia, respectively. The heterogeneity was shown to be 94.6% for myopia, 60% for astigmatism, and 78.8% for hyperopia.

Fig 5. Funnel plot showing the pooled prevalence of visual impairment due to myopia in Ethiopia, 2021.

Fig 5

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Fig 6. Funnel plot showing the pooled prevalence of visual impairment due to astigmatism in Ethiopia, 2021.

Fig 6

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Fig 7. Funnel plot showing the pooled prevalence of visual impairment due to hyperopia in Ethiopia, 2021.

Fig 7

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Subgroup analysis was conducted by region, year of publication, year of study, sample size, professional diagnosing refractive error, study setting, and risk bias of studies. The sub-group conducted by region identified a lower prevalence of refractive error among studies conducted in Addis Ababa (4%), and the heterogeneity was decreased to 0% among studies conducted in Addis Ababa and the Tigray region. The pooled prevalence of refractive error was not varied by the year of publication, but the heterogeneity was decreased to 60% among studies published from 2011 to 2015. Similarly, the pooled prevalence was not varied by the year of data collection, but the heterogeneity is shown to decrease significantly (53%) among studies conducted between 2000 and 2010. Subgroup analysis conducted on the pooled prevalence of refractive error was highest among studies with a sample size between 500–750 (7%). The lowest result was identified among studies with a sample size greater than 750 (5%). In this subgroup, the heterogeneity varied from 67% among studies with a sample size between 751–1000 to 97.1% among studies with a sample size between 500–750. The pooled refractive error prevalence was 4% (95% CI: 3–6) among community-based studies. The heterogeneity decreased from 96% to 0% after subgroup analysis based on the study setting. The pooled prevalence of refractive error was identified to be 7% among studies where refractive error diagnosis was made by an optometrist and 4% among studies where an ophthalmologist made it. In this subgroup, the heterogeneity decreased to 68% among studies where an ophthalmologist made the diagnosis, while it was 95.2% among studies where the diagnosis was made by an optometrist [Table 2].

Table 2. Sub-group analysis by region, year of publication, year of study, professional diagnosed RE, study setting, and sample size on the prevalence of visual impairment due to RE in Ethiopia, 2021.

Sub-group analysis Number of studies VI due to RE% 95% confidence interval Heterogeneity (I2%) P-value
Sub-group analysis by year of publication
1. < 2011 4 6.0 4.0–8.0 79.5 P = 0.002
2. 2011–2015 5 6.0 5.0–7.0 60.6 P = 0.038
3. 2016–2021 13 6.0 4.0–7.0 96.5 P < 0.001
Sub-group analysis by year of study
1. 2000–2010 6 6.0 4.0–8.0 95.8 P< 0.001
2. 2011–2021 16 6.0 5.0–7.0 53.0 P = 0.059
Sub-group analysis by professional who diagnosed RE
1. Ophthalmologist 6 4.0 3.0–5.0 68.0 P = 0.008
2. Optometrist 11 7.0 2.0–9.0 95.2 P < 0.001
3. Not mentioned 5 5.0 5.0–6.0 82.1 P < 0.001
Sub-group analysis by regions
1. Amhara region 8 6.0 5.0–6.0 91.4 P < 0.001
2. Oromia 3 4.0 2.0–7.0 59.8 P < 0.083
3. Addis Ababa 3 4.0 3.0–5.0 0.0 P = 0.556
4. Tigray 1 6.0 4.0–7.0 - -
8. Southern Nation Nationality Region of Ethiopia 7 6.0 3.0–9.0 97.5 P < 0.001
Sub-group analysis by study setting
1. Hospital-based 2 5.0 4.0–7.0 0.0 P < 0.069
2. School-based 15 6.0 5.0–8.0 96.2 P < 0.001
3. Community based 5 4.0 3.0–6.0 73.5 P < 0.004
Sub-group analysis by sample size
1. <500 6 6.0 4.0–9.0 81.4 P < 0.001
2. 501–750 6 7.0 3.0–10.0 97.1 P < 0.001
3. 751–1000 3 5.0 3.0–6.0 67.0 P = 0.048
4. 1001–1250 3 5.0 2.0–8.0 94.5 P < 0.001
5. >1250 4 6.0 5.0–7.0 94.4 P < 0.001
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Discussion

This meta-analysis is the first pooled prevalence of visual impairment due to refractive error in Ethiopia. The pooled prevalence of visual impairment due to refractive error was found to be 6% in Ethiopia, and myopia was identified as the commonest cause of visual impairment due to refractive error. This finding is higher than the pooled prevalence of visual impairment due to RE reported by a meta-analysis conducted in sub-Saharan Africa in 2015 [5]. It is also much higher than the prevalence of uncorrected RE reported by the global burden of disease (0.12%) in 2020 [41]. Further, the current finding is higher than the pooled prevalence of visual impairment due to RE reported by a global meta-analysis conducted in 2004 (1%) [42]. The difference might be explained by the variation of the study period of global metanalysis, which included studies conducted before 2004. The finding of this meta-analysis was also higher than other global meta-analyses conducted in 2010, which revealed the prevalence to be 2.1% [6]. The difference might be from sociodemographic and eye care service differences among various countries included in the analysis.

Subgroup analysis by region in this meta-analysis showed the lowest prevalence of refractive error among studies conducted in Addis Ababa. The difference among the regions may be due to variation in universal health coverage among different regions of Ethiopia. The universal health coverage was 52.2% in Addis Ababa, while 26% in the Oromia region [43].

Subgroup analysis conducted on the pooled prevalence of visual impairment due to refractive error was highest among studies with a sample size between 500–750. At the same time, the lowest result was identified among studies with a sample size greater than 750. This difference may be because a small sample size has an overestimation effect compared with large sample size studies [44]. Further studies with a low sample size have a higher margin of error, and a large margin of error elongates the width of the confidence interval and gives an imprecise measure of the common effect size [45].

The pooled prevalence of visual impairment due to refractive error was higher among studies where an optometrist made a refractive error diagnosis than among studies where an ophthalmologist made a refractive error diagnosis. This difference can be explained by the difference in the skill of professionals in making an appropriate diagnosis of refractive errors. Some studies reported that diagnoses of ocular disease made by optometrists vary from those made by an ophthalmologist [46–49].

Generally, the current systematic review and meta-analysis reveal the prevalence of refractive error in Ethiopia, giving essential evidence for policymakers, clinicians, and other concerned entities who have previously overlooked the burden of refractive error on visual impairment.

Conclusion

In Ethiopia, the pooled prevalence of visual impairment due to refractive error was high. About one in twenty-five Ethiopian children and adolescents are affected by visual impairment due to myopia. Since the refractive error is a correctable cause of visual impairment, it is important to have a national figure in Ethiopia. Recognizing a high prevalence of visual impairment due to refractive error in Ethiopia may prompt policymakers to implement effective control and prevention initiatives to reduce the refractive error burden in Ethiopia.

Supporting information

S1 Checklist. PRISMA checklist.

(DOC)

Click here for additional data file. (62.5KB, doc)
S1 File. Search terms used on different databases for visual impairment due to refractive error in Ethiopia.

(DOCX)

Click here for additional data file. (642.5KB, docx)
S1 Table. Showing the risk of bias assessment of included study for metanalysis of visual impairment in Ethiopia.

(DOCX)

Click here for additional data file. (35KB, docx)

Data Availability

All relevant data are within the paper and its Supporting information files.

Funding Statement

The authors received no specific funding for this work.

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Decision Letter 0

Consolato M Sergi

9 Jun 2022

PONE-D-22-10704Prevalence of Visual Impairment due to Refractive Error among children and adolescents in Ethiopia: A Systematic Review and Meta-Analysis. PLOS ONE

Dear Dr. Atlaw,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Consolato M. Sergi

Academic Editor

PLOS ONE

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Additional Editor Comments:

Thank you for sending this manuscript to Plos One. After careful revision of the reviewers' concerns and criticisms, I would suggest that the authors need to address all issues from both reviewers in detail. I strongly suggest the authors revise the manuscript and replying point-by-point to the major and minor concerns.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

********** 

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

********** 

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

********** 

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: Yes

********** 

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Firstly, the data provided does indeed support the conclusion, however more precision is needed on some points. For example, the text mentioned a global refractive error of 12%, but did not note the year in the text. The year is important as the authors mentioned that the prevalence of refractive error can change with better healthcare.

Few English mistakes have been highlighted in the attached review, with attached comments.

Reviewer #2: Topic:

Prevalence of Visual Impairment due to Refractive Error among children and adolescents in Ethiopia: A Systematic Review and Meta-Analysis.

The authors examined the pooled prevalence of visual impairment due to refractive error in Ethiopia. They found high value of the prevalence of visual impairment owing to refractive error. About one in twenty-five Ethiopian children and adolescents are affected by visual impairment due to refractive error.

Below are few suggestions:

Statistical methods and analysis section:

Under this section, the authors need to cite the relevant sources guiding their choices. That is, the articles that motivated the methods they opted for should be acknowledged with respect to heterogeneity, random effects, and publication bias assessments. For example, for publication bias assessment, the following article could be cited: Egger, M.; Davey Smith, G.; Schneider, M.; Minder, C. Bias in meta-analysis detected by a simple, graphical test. BMJ 1997, 315, 629–634.

This study is more about the assessment of prevalence. The influence of other factors on prevalence involving a meta-regression analysis should be treated on a different occasion. It is most likely a different topic, as it goes beyond the specific objective of the review, i.e. summary of the pooled prevalence of visual impairment due to refractive error. Hence, kindly remove the highlighted statement about meta-regression.

Further remarks:

Beware of the consistency in the spelling of the random-effects model throughout the article. It is ‘random-effects’ and not ‘random-effect’.

Table 2: Please add the sample size for each sub-group in this table. That is, you may mention the number of studies involved in each sub-group in a separate column.

Please see the full text for all the minor suggestions.

********** 

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Reviewer #1: Yes: Youssef Mahfouz

Reviewer #2: Yes: Joseph F. Feulefack

**********

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Attachment

Submitted filename: PLOS_PeerReviewWithComments.pdf

Click here for additional data file. (1.1MB, pdf)
PLoS One. 2022 Aug 18;17(8):e0271313. doi: 10.1371/journal.pone.0271313.r002

Author response to Decision Letter 0

14 Jun 2022

To: PLOS ONE editorial

Response to reviewers

Additional Editor Comments:

Thank you for sending this manuscript to Plos One. After careful revision of the reviewers' concerns and criticisms, I would suggest that the authors need to address all issues from both reviewers in detail. I strongly suggest the authors revise the manuscript and replying point-by-point to the major and minor concerns.

Authors response -Dear respected editorial members of Plos One thank very much for your detailed and constructive comments and suggestions. We have replayed reviewers concern point by point and We have amended all journal requirement requested.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Firstly, the data provided does indeed support the conclusion, however more precision is needed on some points. For example, the text mentioned a global refractive error of 12%, but did not note the year in the text. The year is important as the authors mentioned that the prevalence of refractive error can change with better healthcare.

Author response -Dear respected reviewer #1; Thank you very much for your generous comment that has significantly improved our manuscript. We have added year of study for most of studies referenced in the introduction and discussion. For instance, see page 3 second paragraph line number 1,2 and 4 … page 10 discussion line number 5, 6.

Few English mistakes have been highlighted in the attached review, with attached comments.

Author response – Thank very much for detailed poofread we have corrected comments on the pdf as well as we have repeated proofread and the whole manuscript was amended once again. Any change made after proofreading was highlighted in red color on supplementary file.

New acronym, what is the delineation? Refractive error (RE)

This makes it a run-on sentence. The highlighted text should be a new sentence. Corrected please see page 3 last paragraph line number 2.

Is there a more recent study for comparison? - more recent reference was used for comparison of result in addition to previous reference. See page 10.

Reviewer #2: Topic:

Prevalence of Visual Impairment due to Refractive Error among children and adolescents in Ethiopia: A Systematic Review and Meta-Analysis.

The authors examined the pooled prevalence of visual impairment due to refractive error in Ethiopia. They found high value of the prevalence of visual impairment owing to refractive error. About one in twenty-five Ethiopian children and adolescents are affected by visual impairment due to refractive error.

Authors response – Dear respected reviewer #2 Thank you very much for your important comments and suggestions that advance our manuscript.

Below are few suggestions:

Statistical methods and analysis section:

Under this section, the authors need to cite the relevant sources guiding their choices. That is, the articles that motivated the methods they opted for should be acknowledged with respect to heterogeneity, random effects, and publication bias assessments. For example, for publication bias assessment, the following article could be cited: Egger, M.; Davey Smith, G.; Schneider, M.; Minder, C. Bias in meta-analysis detected by a simple, graphical test. BMJ 1997, 315, 629–634.

Author response- Thank you very much we have cited four references in the method section including the suggested reference see page 6.

37. Tufanaru C, Munn Z, Stephenson M, Aromataris E. Fixed or random effects meta-analysis? Common methodological issues in systematic reviews of effectiveness. Int J Evid Based Healthc. 2015;13(3):196–207.

38. Borenstein M, Hedges L V., Higgins JPT, Rothstein HR. A basic introduction to fixed-effect and random-effects models for meta-analysis. Res Synth Methods. 2010;1(2):97–111.

39. Egger M, Smith GD, Schneider M, Minder C. Bias in meta-analysis detected by a simple , graphical test. BMJ. 1997;(May 2014):629–34.

40. Lin L, Chu H, Murad MH, Hong C, Qu Z, Cole SR, et al. Empirical Comparison of Publication Bias Tests in Meta-Analysis. J Gen Intern Med. 2018;33(8):1260–7.

This study is more about the assessment of prevalence. The influence of other factors on prevalence involving a meta-regression analysis should be treated on a different occasion. It is most likely a different topic, as it goes beyond the specific objective of the review, i.e. summary of the pooled prevalence of visual impairment due to refractive error. Hence, kindly remove the highlighted statement about meta-regression.

Author response – Thank you very much we have deleted statement about meta regression see page 6

Further remarks:

Beware of the consistency in the spelling of the random-effects model throughout the article. It is ‘random-effects’ and not ‘random-effect’.

Author response- Thank you very much We have corrected random-effect into random-effects

Table 2: Please add the sample size for each sub-group in this table. That is, you may mention the number of studies involved in each sub-group in a separate column.

Author response- Thank you very much we have added new column on table two indicating number of studies included. See page 10 table 2

Please see the full text for all the minor suggestions.

Author response- Thank you very much we have revised the whole manuscript and any change made were highlighted in red color

Attachment

Submitted filename: Response to reviwers.docx

Click here for additional data file. (16.3KB, docx)

Decision Letter 1

Consolato M Sergi

29 Jun 2022

Prevalence of Visual Impairment due to Refractive Error among Children and Adolescents in Ethiopia: A Systematic Review and Meta-Analysis.

PONE-D-22-10704R1

Dear Dr. Atlaw,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Consolato M. Sergi

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: (No Response)

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: In the second paragraph of the Abstract, the correct spelling is ‘random-effects’.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Youssef Mahfouz

Reviewer #2: Yes: Joseph Florent Feulefack

**********

Acceptance letter

Consolato M Sergi

2 Aug 2022

PONE-D-22-10704R1

Prevalence of visual impairment due to refractive error among children and adolescents in Ethiopia: a systematic review and meta-analysis.

Dear Dr. Atlaw:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Professor Consolato M. Sergi

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Checklist. PRISMA checklist.

    (DOC)

    Click here for additional data file. (62.5KB, doc)
    S1 File. Search terms used on different databases for visual impairment due to refractive error in Ethiopia.

    (DOCX)

    Click here for additional data file. (642.5KB, docx)
    S1 Table. Showing the risk of bias assessment of included study for metanalysis of visual impairment in Ethiopia.

    (DOCX)

    Click here for additional data file. (35KB, docx)
    Attachment

    Submitted filename: PLOS_PeerReviewWithComments.pdf

    Click here for additional data file. (1.1MB, pdf)
    Attachment

    Submitted filename: Response to reviwers.docx

    Click here for additional data file. (16.3KB, docx)

    Data Availability Statement

    All relevant data are within the paper and its Supporting information files.

    Articles from PLoS ONE are provided here courtesy of PLOS

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