SynthesisJournal of optometry
Prevalence of refractive error in Portugal - A systematic review and meta-analysis.
Synthesis in Journal of optometry. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
5 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Prevalence of refractive errors among school students in Iraq - A systematic review and meta-analysis.Journal of optometryPooled it
- Spherical Equivalent Percentile Curves in a Portuguese School-Aged Population.Journal of clinical medicine · 2025Article
- Factors associated with myopia in the Portuguese child population: An epidemiological study.Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) · 2025Article
- Integration of Refractive Services Provided by Optometrists into the Portuguese National Health Service.Portuguese journal of public health · 2023Article
- Prevalence of refractive error in Portugal estimated from ophthalmic lens manufacturing data: Ten-years analysis.PloS one · 2023Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeThe aim of this study was to systematically review and meta-analyse epidemiological data of refractive error prevalence in Portugal.
methodsA structured search strategy and systematic literature review was applied to multiple databases, such as MEDLINE/PubMed, Web of Science, Scopus, Google Scholar, official organizations and academic repositorium's, to identify all relevant epidemiological studies in Portugal until February 2021. The outcome measure was the prevalence of refractive error among the Portuguese population. The events and sample size were entered as raw data and the effect size parameters were computed by Comprehensive Meta-Analysis Software.
resultsA total of 9 studies were pooled for the meta-analysis. The fixed effects model points to an estimated effect size of 43% (95% CI: 41.9-44.1%). However, the statistics of heterogeneity (Q-value p < 0.001; I-squared =99.344) showed very high heterogeneity among studies and recommends using a random-effects model. The random effects model points to an estimated effect size of 31.9% (95% CI: 19.8-47.0%) prevalence of refractive error in the Portuguese population.
conclusionsA prevalence of refractive error in Portugal of 31.9% (95% CI: 20.0-47.0%) can be considered as a conservative approach to the real burden of this condition. However, it translates into at least 2 to 4.5 million Portuguese individuals with a refractive error. The high heterogeneity between studies, the wide estimate and the random effects involved demonstrate the need for more studies and consistent sources to obtain narrower estimates.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.