Critical insights into the ocular surface microbiome: the need to standardize

Data from the literature indicates that the human ocular surface is inhabited by diverse commensal microbial communities, crucial for maintaining the homeostasis of healthy eyes. The ocular surface microbiome (OSM) plays a protective immunoregulatory role against pathogenic species, and any dysbiosis may contribute to disease onset. Traditional culture methods, employed in both clinical and research settings, have limitations. Certain pathogens are challenging to grow under routine conditions, leading to lower bacterial detection compared to next-generation sequencing (NGS). Despite the extensive use of NGS in published studies, variable results are observed. This variability may be attributed to factors such as limited sample size, differences in analytical procedures (from sampling to sequencing platforms), age and gender variations in included populations, diverse inclusion criteria, and geographical differences. These factors collectively impact the generated genomic data. Moreover, consistent reports on diversity indices are lacking in various published studies, whereas these indices could enhance the definition of OSM changes in disease states. Therefore, this review emphasizes the current imperative to standardize OSM sample collection, preparation, and analysis. This standardization is vital for accurately defining the composition of OSM in both healthy and pathogenic conditions and facilitating meaningful comparisons among studies.