Abstract
Systematic reviews (SRs) and meta-analyses (MAs) are of great importance for basing clinical decisions. However, misleading interpretations may result when informed decisions rest on biased review papers with methodological issues. To evaluate which treatment is optimal, an overview was made of SRs and MAs to establish the quality and certainty of meta-evidence published on the efficacy of laser-based refractive surgery techniques for treating myopia in adults. A search was made in five databases and was updated using Really Simple Syndication (RSS) feed appliances up to April 2021; SRs with or without MAs were included. Methodological quality was appraised using the AMSTAR-2 tool. The best available reviews were summarized using the GRADE approach. The corrected covered area (CCA) was used to determine the degree of over-representation of publications. The risk of bias of the primary studies was disclosed visually. Thirty-six studies published between 2003 and 2021 were included. Twenty SRs (56%) were conducted in China. The most studied comparisons were SMILE versus FS-LASIK (19%) and FS-LASIK versus MM-LASIK (11%). Of the 251 overlapping index publications, 165 were unique (CCA = 0.015%), representing a negligible risk of skewed reporting. The AMSTAR-2 tool showed most SRs to have critically low or low quality. Nine reviews presented moderate quality. The GRADE approach of the 41 a priori outcomes evidenced critically low and low certainty of evidence. Only the spherical equivalent refraction changes at 12 months between LASEK and PRK showed moderate certainty of evidence, favouring PRK (mean difference 0.06, 95%CI [-0.02 to 0.14], I(2) = 0%; p ≥ 0.05). Index trials among less biased reviews are prone to selection, performance and reporting bias. The appraised techniques exhibit comparable results in terms of efficacy. There is moderate certainty of evidence in favour of the use of PRK over LASEK in terms of the spherical equivalent refraction error changes at 1 year of follow-up. Most appraised SRs presented methodological flaws in critical domains, resulting in a low to critically low certainty of evidence after GRADE appraisal. Therefore, investigators need to study and compare the different laser-based refractive techniques to provide better evidence-based medicine. Further well-designed, high-quality clinical trials and SRs are needed to reappraise the current findings.