A comparative meta-analysis of amniotic membrane preservation methods: Balancing biological potency and clinical feasibility in ophthalmology

Abstract

Objectives: The objective of the study is to systematically compare biological and structural properties of fresh, cryopreserved, lyophilized, and dehydrated human amniotic membrane (AM) and to quantify sufficiently comparable outcomes across preservation methods. Material and Methods: PubMed/MEDLINE was searched for comparative human AM studies published from January 2000 to March 10, 2026. Eligible studies compared at least two preservation or preparation modalities and reported biochemical, cellular, structural, mechanical, or ophthalmic outcomes. Quantitative syntheses used log ratios of means and random-effects models with restricted maximum likelihood and modified Hartung-Knapp confidence intervals. Methodological limitations were assessed with domains tailored to ex vivo experiments. Results: Of 497 records screened, 48 reports were sought, 46 were assessed in full text, and 44 studies were included; six unique studies contributed to two exploratory meta-analyses. For epidermal growth factor, the pooled dried/dehydrated-to-frozen ratio of means was 1.54 (95% confidence interval [CI], 0.35–6.70; I2 = 92.0%). For cellular viability, the cryopreserved-to-fresh ratio was 0.32 (95% CI, 0.03–3.11; I 2 = 96.2%) using the placental-region estimate and 0.44 (95% CI, 0.07–2.60; I 2 = 90.9%) using the reflected-region sensitivity estimate. Neither synthesis established superiority. Conclusion: Preservation method influences human AM properties, but the quantitative evidence is sparse, heterogeneous, and protocol-dependent. Current data do not support a universal hierarchy of preservation modalities; selection should reflect the biological property required, processing quality, and clinical logistics.