UNLABELLED: A healthy ocular surface is characterized by relatively stable and comparatively low microbial diversity. However, pathological conditions can provoke shifts in the composition of bacterial taxa, which may be associated, among other factors, with the progression of myopia.

PURPOSE: This study compared the taxonomic diversity of the conjunctival microbiota in children with varying degrees of myopia and those without clinically confirmed myopia.

MATERIAL AND METHODS: Ocular surface samples were obtained from 29 children aged 6-17 years with myopia (58 eyes) and from 12 children of the control group aged 9-17 years (24 eyes). The taxonomic composition of the conjunctival microbiota was analyzed using 16S ribosomal RNA gene (rRNA) sequencing, followed by microbiome profiling through bioinformatics and statistical tools.

RESULTS: The ocular surface microbiota in children with myopia demonstrated higher alpha diversity compared to the control group. This was confirmed by values of the Chao (reflecting low-abundance taxa) and Shannon (reflecting overall bacterial diversity - higher diversity means higher index; optimal value; 3.1-4.2) indices. The results revealed a clear trend toward differentiation in bacterial composition between myopic and control groups. These differences were associated with changes in the relative abundance of opportunistic bacteria depending on the degree of myopia.

CONCLUSION: The taxonomic diversity of the ocular microbiota at the genus level in patients with varying degrees of myopia was characterized by a higher number of taxonomic units compared to the control group. The general trend is an increase in the biodiversity of the bacterial composition due to an increase in the relative representation of opportunistic microorganisms. Further research on the influence of the ocular microbiota on the progression of myopia is needed.