Journal of Eye Diseases and Disorders

The Role of Ocular Microbiome in Chronic Conjunctivitis: Emerging Insights and Clinical Implications

Mikhail Andropov^* Department of Ocular Immunobiology, Saint Petersburg Medical University, Saint Petersburg, Russia
^*Correspondence: Mikhail Andropov, Department of Ocular Immunobiology, Saint Petersburg Medical University, Saint Petersburg, Russia, Email:

Received: 03-Mar-2025, Manuscript No. JEDD-25-29166; Editor assigned: 05-Mar-2025, Pre QC No. JEDD-25-29166 (PQ); Reviewed: 19-Mar-2025, QC No. JEDD-25-29166; Revised: 26-Mar-2025, Manuscript No. JEDD-25-29166 (R); , DOI: 10.35248/2694-1622.25.10.269

Description

Chronic conjunctivitis is a persistent inflammatory condition of the conjunctiva that poses diagnostic and therapeutic challenges due to its multifactorial etiology and resistance to standard treatments. While traditionally considered to be of allergic, infectious, or toxic origin, emerging research highlights the importance of the ocular microbiome in maintaining immune homeostasis and influencing disease progression. The human eye, once assumed to be a sterile environment, is now recognized as hosting a unique and dynamic microbial community that interacts intimately with host tissues and the immune system.

Recent advances in high-throughput sequencing and metagenomics have enabled the identification of diverse microbial taxa residing on the ocular surface, including commensals such as Corynebacterium, Staphylococcus epidermidis, and Propionibacterium. These organisms contribute to local immunity by competing with pathogenic species, modulating inflammatory pathways, and enhancing epithelial barrier function. Disruption of this microbial equilibrium, a state known as dysbiosis, has been linked to the pathogenesis of chronic ocular surface disorders including conjunctivitis, blepharitis, and dry eye syndrome.

In chronic conjunctivitis, particularly in cases that are idiopathic or refractory to conventional therapy, microbial imbalance appears to play a significant role. Studies comparing the microbiota of affected patients and healthy controls reveal altered species richness, reduced microbial diversity, and overrepresentation of potentially pathogenic genera such as Pseudomonas, Moraxella, and Staphylococcus aureus. These changes may result in persistent low-grade inflammation, immune dysregulation, and increased susceptibility to secondary infections.

Mechanistically, dysbiosis may contribute to chronic conjunctival inflammation through the activation of pattern recognition receptors, including Toll-like receptors (TLRs), on conjunctival epithelial cells and resident immune cells. This triggers the release of pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α, leading to recruitment of neutrophils and lymphocytes. Moreover, the breakdown of the mucin layer due to microbial enzymes can compromise the tear film and epithelial integrity, exacerbating the inflammatory response and perpetuating a cycle of irritation and immune activation.

The role of external factors such as antibiotic usage, contact lens wear, environmental pollutants, and ocular surgeries in disturbing the ocular microbiome has also come under scrutiny. Frequent use of topical antibiotics, while intended to control infection, may inadvertently eliminate beneficial commensals, allowing opportunistic pathogens to thrive. Similarly, long-term contact lens wear has been associated with microbiota shifts that favor gram-negative bacteria and biofilm formation, increasing the risk of chronic inflammation and microbial keratitis.

Therapeutic strategies targeting the ocular microbiome are in early stages but show considerable promise. Probiotic and prebiotic formulations, already in use for gastrointestinal disorders, are being investigated for topical ophthalmic application. These aim to restore microbial balance and enhance mucosal immunity without the collateral damage associated with broad-spectrum antibiotics. In vitro and animal studies using Lactobacillus and Bifidobacterium strains suggest reduced inflammation and improved epithelial healing in conjunctival injury models. Clinical trials are underway to evaluate the efficacy and safety of such treatments in humans.

Additionally, microbiome analysis is being explored as a diagnostic tool to identify biomarkers of disease and predict treatment response. Personalized medicine approaches could use microbiota profiles to guide antibiotic selection, monitor disease progression, or detect early signs of relapse. The development of rapid point-of-care sequencing platforms may soon allow for microbiome-based diagnostics in routine clinical practice, providing new dimensions to patient stratification and management.

However, challenges remain in translating these insights into clinical interventions. The ocular microbiome is relatively low in biomass, making sample collection and contamination control critical issues in study design. Furthermore, inter-individual variability in microbial composition, influenced by genetics, geography, and lifestyle, complicates the establishment of a universal “healthy” ocular microbiome. More longitudinal studies are needed to understand the temporal dynamics of microbial communities and their interaction with host immunity.

Ethical and regulatory considerations also arise with the introduction of live biotherapeutic products in ophthalmology. Ensuring sterility, efficacy, and safety while maintaining microbial viability requires sophisticated formulation and storage technologies. Regulatory bodies are currently developing guidelines to oversee the approval and monitoring of microbiome-based therapeutics, a process that must balance innovation with patient protection.