Allergic conjunctivitis in Northeast India: Environmental drivers, clinical patterns, and emerging public health concerns

Allergic conjunctivitis (AC) is one of the most common ocular surface inflammatory conditions and contributes significantly to ophthalmology outpatient visits worldwide. Despite its high prevalence, the condition is often underestimated, particularly in resource-limited and environmentally vulnerable regions. North-East India, characterized by high humidity, dense vegetation, and prolonged rainy seasons, provides a unique ecological setting that may influence the burden and pattern of ocular allergic diseases. To review the epidemiology, environmental determinants, clinical spectrum, and management of AC, with special emphasis on its public health relevance in North-East India. This study was conducted as a structured narrative review with a systematic literature search. Electronic databases, including PubMed and Google Scholar, were searched for articles published between 2010 and 2025 using relevant keywords related to AC, ocular allergy, environmental allergens, and North-East India. Original studies, meta-analyses, reviews, and epidemiological reports were included. Due to heterogeneity in study design and outcomes, findings were synthesized qualitatively. AC encompasses a spectrum ranging from mild seasonal and perennial forms to severe variants such as vernal and atopic keratoconjunctivitis, which may lead to conjunctival and corneal complications leading to visual impairment if inadequately managed. Environmental factors in North-East India, including high aeroallergen load from pollen, fungal spores, and dust mites, play a significant role in disease occurrence, exacerbation and complications. Indoor factors such as damp housing and biomass exposure further contribute to sustained allergen exposure. The condition frequently coexists with systemic atopic disorders, including allergic rhinitis and asthma, forming part of a unified allergic response. In children, associated allergic rhinitis may contribute to sleep-disordered breathing, adenoid hypertrophy, recurrent tonsillitis, and otitis media with effusion, leading to hearing impairment and adverse effects on academic performance. Despite these implications, the true burden of AC in the region remains understudied and underreported, with most data derived from hospital-based studies. AC in North-East India represents a clinically significant yet under-recognized public health concern. Its association with environmental factors, systemic atopy, and potential for preventable visual and developmental morbidity underscores the need for increased awareness and early intervention. Strengthening population-based research, allergen mapping, and integration of ocular allergy into primary healthcare and school health programs is essential to reduce disease burden and improve long-term outcomes.