The purpose of this systematic review and meta-analysis is to determine the pooled prevalence, pattern, and factors associated with ocular protection practices in small-scale welders in sub-Saharan Africa. To ensure the accuracy and completeness of the study, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist was used (21) (Supplementary material S1).

Two approaches were followed to search potentially relevant studies. The electronic database search (PubMed, Google Scholar, Hinari, and Institution research repositories) and the manually search of the reference list of the previous prevalence studies were carried out to retrieve more articles. The literature search was limited to studies published in English that examined the pooled prevalence, pattern, and factors associated with ocular protection practices among welders in sub-Saharan Africa. To ensure comprehensive coverage of the literature, the reference lists of the included studies were carefully checked. A systematic approach was followed to conduct an advanced search on PubMed. Initially, search terms were formulated for four key areas: “Ocular protection practices,” “associated factors,” “Welders,” and “Sub-Saharan Africa.” These keywords were retrieved from Google Scholar and then individually searched in PubMed to identify relevant MeSH terms within the MeSH hierarchy tree. These terms were then combined using advanced Boolean search logic, specifically using the “AND” and “OR” operators to effectively bring the concepts together. The search was also made by combining the above search terms with the names of all countries included in sub-Saharan Africa. The search period was from July 1/2023 to August 10/2023. The three investigators (YAA, KAG, and NAG) independently and carefully reviewed the contents of each retrieved articles. Those literatures fulfilling the following criteria were finally included in the review.

Population: Welders. Exposure: Exposure is a key factor that increases or decreases the likelihood of Ocular protection practice among small-scale industry welders in Sub-Saharan Africa. Context: Sub-Saharan Africa. Condition: Ocular protection practices. Outcome measurement: The primary outcome of the study was the prevalence of ocular protection practices among welder workers in small-scale industries in sub-Saharan Africa. The secondary outcome of the study was determinants influencing the primary outcomes.

The present study included primary research studies that reported on the dissemination of pooled prevalence, pattern, and factors associated with ocular protection practices among welders in sub-Saharan Africa. The review included full-text articles in English as well as primary studies involving welders. Both published and unpublished articles were considered. However, studies without full-text access and articles that did not provide sufficient information on the outcomes of interest (ocular protection practices) were excluded. In addition, studies were not freely available in full text and those that used a qualitative study design were excluded from the review.

Three authors (YAA, KAG, and NAG) working independently abstracted the relevant data from studies by using a standardized Microsoft Excel spreadsheet. The JBI tool for prevalence studies (22) was used as a guideline for data extraction from the finally selected articles. The data extraction tool contains information on the author and year of the study, title, year study was conducted and year of publication, study area and country, sub-region, study design and type, sample size, response rate, the outcome measured, and prevalence rate. Information regarding the publication status was also collected. Additionally, the tool contains information on the study quality scores.

After screening the relevant studies, the selected studies were critically appraised for methodological validity using Joanna Briggs Institute (JBI) appraisal tools for prevalence studies (22). The tool had a total of 8 questions (Q1–Q8) and those studies with positive answer of more than 50% of the tool (i.e. “Yes” for 5 or more question of JBI tool) were included for this meta- analysis. These scoring was done by two investigators (YAA and KAG) with the discrepancies were resolved with discussion and consensus.

When the disagreement between the two authors was not resolved with discussion, the third author (NAG) involved was as breaker. During critical appraisal of each primary study, more emphasis was given to the appropriateness of the study objectives, study design, sampling technique, data collection technique, statistical analysis, any sources of bias, and its management technique. The parameters are about the following questions: Where were the criteria for inclusion in the sample clearly defined? Were the study subjects and, therefore, the setting described in detail? Was the exposure measured result validly and reliably? Were the main objective and standard criteria used to measure the event? Where confounding factors identified? Were strategies to affect confounding factors stated? Were the results measured indeed and dependably? And, was the statistical analysis suitable? (Supplementary material S2).

Small-scale industry: Industries with fewer than 10 employees that use power-driven machines.

Ocular protection practice: Participants who scored at the mean and above were considered to have good eye protection practices, while participants who scored below the mean were considered to have poor eye protection practices. Welder: People who carry out welding or other work in welding workshops. Small-scale welding: places like welding houses, garages, and furniture. Ocular injury: Any injury occurring to the eye and or adnexa that occurred in the participant's regular place of work during working hours in the past year.

The data analysis software Stata version 14 was utilized to perform the statistical analysis. The pooled prevalence estimation was performed using the random effects technique, the foundation of which is the inverse variance method. The evaluation of heterogeneity among research studies was conducted by computing the I² statistic. This statistical measure is the percentage of total variation among studies that can be attributed to heterogeneity rather than chance.

The levels of heterogeneity were denoted as low, moderate, and high using values of 25%, 50%, and 75%, respectively. Sensitivity analysis with the “leave-one-out” approach was used to evaluate the possible impact of any particular study on the meta-analysis. Additional analyses were conducted by considering subgroups to explore potential sources of heterogeneity. The researchers employed Egger's linear regression test and funnel plot examination to investigate potential publication bias. A 95% confidence interval accompanied the measured-adjusted odds ratio.

This systematic review and meta-analysis included published studies conducted on prevalence, pattern, and factors associated with ocular protection practices among welders in sub-Saharan Africa. A total of 2,326 records were retrieved through electronic database searching. From these, 1,016 duplicated records were excluded, and from 1,310 articles screened using their titles and abstracts, 1,218 were excluded. Ninety-two full-text articles were assessed for eligibility. From these, 75 full-text articles were excluded from prior criteria, and finally, 17 full-text primary articles were selected for quantitative analysis (Figure 1).

Seventeen primary studies (6, 14, 23–37) involving 4,496 participants were included in the systematic review and meta-analysis, and all studies were published from 2003 to 2023. The sample size ranged from 58 to 433. Seven studies were conducted in Nigeria (14, 28, 30–32, 34, 35), two studies in Ghana (6, 29), two studies in South Africa (24, 36), two studies in Ethiopia (27, 33), two studies in Uganda (25, 26), one study in Kenya (23) and, one study in Tanzania (37). The risk level of each study was assessed and we found that all studies were rated as low risk of bias. Regarding the study design, all studies used a cross-sectional study design. Furthermore, the primary studies were categorized according to their sub-regions, six studies were conducted in East Africa (23, 25–27, 33, 37), nine studies were in West African countries (6, 14, 28–32, 34, 35), two studies were in South African countries (24, 36) (Table 1).

A comprehensive analysis was conducted on a sample of 4,496 participants to determine their level of good ocular protection practice among welders in small-scale industries. The study included a total of seventeen research studies from this, six in East Africa, nine studies in West Africa, and two studies in Southern African countries. The overall pooled prevalence level of ocular protection practice in sub-Saharan Africa was 53.71% (95% CI: 42.54, 64.88). It was determined using the random-effect model. This estimate was statistically significant at a P-value ? 0.001. Furthermore, heterogeneity between studies was found to be high with an I² value of 98.6% (Figure 2).

To examine the effects of sub-regions, subgroup analysis was conducted. It was found that the study conducted in Southern Africa had the highest combined prevalence of ocular protection practices among welders, reaching 81.30% (95% CI: 65.64, 96.97). Furthermore, I² statistics showed a significant level of heterogeneity (I²: 98.6%, P < 0.001) between studies. Similarly, the second highest pooled prevalence of ocular protection practice among welders in sub-Saharan Africa was found in Eastern Africa with 57.33% (95% CI: 40.90, 73.76), and I² statistics showed a high degree of heterogeneity (I²: 98.4%, P < 0.001) between studies. On the other hand, West Africa had the lowest pooled prevalence at 45.18% (95% CI: 29.39, 60.98), and I² statistic showed a high degree of heterogeneity (I²: 98.6%, P < 0.001) between studies (Table 2).

In addition to conducting subgroup analyses, we performed a sensitivity analysis by excluding each study to investigate the origin of heterogeneity. This analysis showed that omitting one study had no statistically significant effect on the overall evaluation of the studies (Table 3).

A meta-regression analysis was performed to determine the presence of statistically significant heterogeneity, indicated by an I-squared test statistic of <0.05. The main objective of this analysis was to identify the underlying cause of heterogeneity to ensure an accurate interpretation of the research results. However, the results of the meta-regression analysis did not show any significant variables that could account for the observed heterogeneity. In particular, there were no statistically significant study-level covariates such as sample size or publication year, country, and sub-region that could explain the differences in the level of good eye protection practices among welders. It can be concluded that the heterogeneity observed in this review is likely due to other factors not considered in the analysis (Table 4).

The presence of publication bias was assessed using a funnel plot and the application of the Egger and Begg regression test at a significant level of 5%. The symmetrical arrangement of the included studies, as shown in the funnel diagram, indicated the absence of publication bias. Furthermore, there was no statistical evidence to support the existence of publication bias, and Begg and Egger tests yielded p-values of 0.773 and 0.365, respectively, which were not statistically significant. Consequently, the test results provide no evidence of a small study effect (Figure 3).

A meta-analysis was conducted using the random effects model to determine the factors associated with ocular protection practices. Therefore, this review found a significant association between the pooled prevalence of ocular protection practice and factors such as training, work experience, and history of workplace eye injuries.

Based on five studies (6, 25–27, 36), we determined statistical significance for the provision of training for welders in small-scale industries. The result showed that the combined effect of training among welders in small industries was significantly related to ocular protection practice in the workplace. Workers who had received occupational safety training were 4.97 times more likely to have practiced ocular protection than workers who had not received occupational safety training [AOR: 4.97, 95% CI: (2.64, 9.36)]. Moderate heterogeneity was observed across studies (I² = 68.1%, p = 0.0.014), for this reason, we used a random effects model (Figure 4).

In addition, the influence of work experience on welders' ocular protection practices was examined through the analysis of seven studies (26, 27, 29–31, 35, 36). The results showed a significant association between welders' work experience and ocular protection practices. Specifically, those with work experience were found to be 4.94 times more likely to adopt ocular protection practices than the reference group (AOR: 4.94, 95% CI: 3.24, 7.54). A random effects model was used (I² = 53.0%, p = 0.047) (Figure 5).

Finally, four studies showed that a history of eye injury in workers was significantly associated with ocular protection practices (6, 25, 27, 28). Welders with a history of eye injuries in the past year were 2.99 times more likely to perform eye protection practices than reference subjects [AOR: 2.99, 95% CI: (1.58, 5.66)]. Since the heterogeneity was moderate, we used a random effects model (I² = 76.6%, p = 0.005) (Figure 6).