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A clinical study on patterns of vernal keratoconjunctivitis among children in rural part of North-East India
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Received: ,
Accepted: ,
How to cite this article: Bhuyan J, Das I. A clinical study on patterns of vernal keratoconjunctivitis among children in rural part of North-East India. J Ophthalmic Res Pract. doi: 10.25259/JORP_3_2026
Abstract
Objectives:
The objective of the study is to evaluate the demographic profile, clinical patterns, and environmental risk factors of vernal keratoconjunctivitis (VKC) among children attending a tertiary care center in a rural region of North-East India.
Material and Methods:
This hospital-based descriptive cross-sectional study was conducted from February 2024 to January 2025. It included 100 children (aged 0–18 years) clinically diagnosed with VKC. Data regarding demographics, clinical signs, symptoms, and environmental exposures (including cooking fuel and animal contact) were collected using a structured pro forma.
Results:
The mean age of presentation was 12.02 years, with a significant male preponderance (male: female ratio 2.03:1). Symptom exacerbation peaked in May. The most common symptom was intense itching (91%), and the most common sign was conjunctival hyperemia (88%). The Limbal variant was the predominant phenotype (72%). A significant association was observed with the use of firewood/kerosene for indoor cooking.
Conclusion:
VKC in North-East India predominantly affects young males and presents chiefly as the Limbal form. Indoor air pollution from biomass fuels is a significant modifiable risk factor in this rural population.
Keywords
Allergy
Biomass fuel
Limbal
North-East India
Vernal keratoconjunctivitis
INTRODUCTION
Vernal keratoconjunctivitis (VKC) is a chronic, bilateral, and recurrent inflammatory disease of the ocular surface that predominantly affects children and adolescents. Historically termed “vernal” implying a spring-time occurrence, the disease is now understood to be a severe form of allergic conjunctivitis that can persist year-round, particularly in tropical and subtropical regions.[1] While often self-limiting with remission typically occurring after puberty, the active phase of the disease is characterized by intense ocular morbidity that can significantly impact the quality of life, school attendance, and psychosocial development of affected children.[2,3] The pathophysiology of VKC is complex and distinct from simple seasonal allergic conjunctivitis. It is considered a multifactorial disorder involving both immunoglobulin E (IgE)-mediated (Type I) and T-cell-mediated (Type IV) hypersensitivity mechanisms. The inflammatory cascade is driven by the infiltration of eosinophils, mast cells, lymphocytes, and plasma cells into the conjunctival substantia propria. The release of chemical mediators such as histamine, prostaglandins, and cytokines contributes to the hallmark symptom of intense pruritus. Furthermore, the release of epitheliotoxic proteins from eosinophils, such as major basic protein and eosinophil cationic protein, is directly responsible for corneal damage, leading to sight-threatening complications such as punctate epithelial keratitis, shield ulcers, and plaque formation.[1] The chronic inflammation also induces tissue remodeling, resulting in the formation of giant “cobblestone” papillae on the tarsal conjunctiva and gelatinous hypertrophy at the limbus.
VKC exhibits a strong geographical variation, being most prevalent in hot, humid, and windy climates. In India, which provides a favorable tropical environment for allergens, the disease is a significant public health concern. Comprehensive multi-geographic analyses across India have estimated a community prevalence of approximately 1.11% among children aged 5–15 years.[4] This disease is found mostly among young children and adolescents (92% of patients between ages 5 and 13 years[5]), and remission occurs by the late teens in 95% cases, with a typical male preponderance of 1.5:1.[6] The demographic profile classically shows a marked male preponderance, particularly in the first decade of life, a finding consistent across various tertiary care studies.[7]
While genetic predisposition and atopy (history of asthma, eczema, or allergic rhinitis) are well-established internal risk factors, external environmental triggers play a crucial role in the exacerbation of the disease. Common allergens include pollen, dust mites, and fungal spores. However, in developing nations and rural settings, other environmental variables such as exposure to smoke from biomass fuels (firewood, kerosene) and proximity to livestock may act as significant non-specific irritants that compromise the tear film stability and lower the threshold for allergic sensitization.[8-10] Despite the high burden of VKC in India, there is a paucity of literature specifically focusing on the rural populations of the NorthEast region. This region is distinct in its climatic conditions, vegetation, and lifestyle practices. Furthermore, while the clinical spectrum of VKC – ranging from the palpebral and limbal forms to mixed presentations – is well documented, the specific association between rural environmental pollutants (such as indoor cooking smoke) and VKC severity remains an area requiring further exploration in this demographic. This study, therefore, aims to evaluate the demographic profile, clinical patterns, and potential environmental risk factors of VKC among children attending a tertiary care center in a rural part of North-East India. By understanding the local disease characteristics and identifying modifiable risk factors, clinicians can tailor management strategies to better control this potentially blinding condition.
MATERIAL AND METHODS
Study design and setting
This hospital-based descriptive cross-sectional study was conducted at the Department of Ophthalmology in a tertiary care teaching hospital situated in a rural region of North-East India. The study was carried out over a period of 1 year, from February 2024 to January 2025. This setting serves a predominantly rural population, providing a unique opportunity to assess environmental risk factors specific to this demographic.
Study population
The study population comprised children presenting to the outpatient department with ocular complaints suggestive of allergic eye disease.
Inclusion Criteria: All children aged 0–18 years who were clinically diagnosed with VKC, defined by severe ocular itching and at least one objective sign (superior tarsal papillae >0.3 mm, limbal Horner–Trantas dots, gelatinous limbal hypertrophy)
Sampling: At the end of 1 year, records of all the patients satisfying the inclusion criteria are collected, and among them, 100 children were selected for the study using a simple random sampling technique (using a lottery method).
Data collection procedure
All patients underwent a comprehensive evaluation.
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History Taking: A detailed history was obtained from the parents or guardians using a pre-structured pro forma. Specific emphasis was placed on:
Demographics: Age, gender, and residence
Symptomatology: Presence and duration of itching, watering, redness, photophobia, and ropy discharge
Pattern of Disease: History of seasonal exacerbation versus perennial persistence
Risk Factors: A thorough inquiry was made regarding personal or family history of atopy (asthma, eczema, allergic rhinitis). Crucially, environmental exposure history was recorded, specifically looking for indoor air pollution sources (use of firewood or kerosene for cooking, average cooking duration, presence of ventilation setup in the house), exposure to dust, and close contact with domestic animals.
Clinical Examination: Visual acuity was assessed using Snellen’s chart for cooperative children and fixation patterns for pre-verbal children. A meticulous slit-lamp biomicroscopic examination was performed to identify hallmark signs of VKC. The upper tarsal conjunctiva was examined after lid eversion to look for papillae.
Clinical classification
Based on the clinical presentation, patients were classified into three types:
Palpebral: Characterized by the presence of papillae (>0.3 mm) on the upper tarsal conjunctiva
Limbal: Characterized by gelatinous thickening of the limbus or Horner–Trantas dots
Mixed: Exhibiting features of both palpebral and limbal forms.
Statistical analysis
The data collected were tabulated and analyzed using standard statistical methods. Descriptive statistics were used to calculate frequencies, percentages, and means for demographic and clinical variables. The Chi-square test was employed to determine statistical significance where applicable.
Consent
Written informed consent was obtained from the parents or legal guardians of all participating children after explaining the nature and purpose of the study.
RESULTS
Demographic profile
A total of 100 children meeting the inclusion criteria were evaluated. The age of the patients ranged from 0 to 18 years. The distribution of cases showed a significant peak in the pre-adolescent and early adolescent age groups, with the maximum number of cases (35%) observed in the 11–12-year age group, followed by the 13–14-year group (22%) [Figure 1]. The mean age of presentation was calculated to be 12.02 years. A clear male preponderance was observed in the study population, with a male: female ratio of 2.03:1 [Figure 2].
Seasonal variation
The occurrence of symptoms demonstrated marked seasonal variation. The highest number of cases was recorded during the month of May, coinciding with the onset of the hot and humid season in the region [Figure 3].
Clinical presentations
The most consistent symptom reported was intense ocular itching, present in 91% of cases. This was followed by watering (85%), redness, mucopurulent discharge, dimness of vision, photophobia, and pain [Figure 4].
Upon clinical examination, the most common sign observed was conjunctival hyperemia, noted in 88% of eyes. Other significant signs included superior tarsal papillae (>0.3 mm) and limbal alterations (Horner–Trantas dots or gelatinous thickening of limbus), keratopathy (superficial punctate keratitis or shield ulcer), and conjunctival pigmentations [Figure 5]. Regarding the history of the disease course, 42% of patients presented with their first episode, while the majority (58%) gave a history of recurrence. Among the recurrent cases (n = 58), the chronic perennial form was the most common presentation (47 cases), whereas the seasonal form was seen in 11 cases [Figure 6].
In terms of visual acuity, the majority of children retained good vision (6/18 or better in Snellen’s Acuity Chart); however, accurate Snellen acuity could not be assessed in 5 children (younger than 4 years of age), who were evaluated based on their ability to fixate and follow light [Figure 7].
Clinical classification
Based on the specific pattern of signs, the study population showed a distinct dominance of the Limbal variant, which constituted 72% of the cases. The palpebral and mixed forms were less frequent [Figure 8].
Environmental risk factors
The most prevalent environmental risk factor identified was the exposure to biomass fuel (firewood or kerosene) for cooking (86%). All of them had a history of cooking duration of more than 5 h on average daily in the absence of ventilation in the house. Other commonly observed risk factors included close contact with domestic animals and exposure to dust [Figure 9]. Among the 100 VKC patients studied, firewood/kerosene use during cooking was present in 86% (95% confidence interval [CI]: 78.1–93.9%), close animal contact in 78% (95% CI: 69.8–86.2%), and dust exposure in 54% (95% CI: 44.2–63.8%). The prevalence of firewood/kerosene use and close animal contact was each significantly >50% (P < 0.001), while dust exposure showed no significant predominance (P = 0.424) [Table 1].
| Risk factor | Exposed (%) | 95% CI | z- score | P-value |
|---|---|---|---|---|
| Firewood/kerosene use | 86 (86) | 78.1–93.9 | 7.2 | <0.001 |
| Close animal contact | 78 (78) | 69.8–86.2 | 5.6 | <0.001 |
| Dust exposure | 54 (54) | 44.2–63.8 | 0.8 | 0.424 |
CI: Confidence interval, VKC: Vernal keratoconjunctivitis. P<0.05 significant
DISCUSSION
The present study provides a detailed clinical and demographic profile of VKC in a rural cohort of North-East India. While VKC is a global entity, its phenotypic expression is known to vary significantly based on geography, climate, and socioeconomic factors. Our findings reinforce the understanding of VKC as a significant ocular morbidity in tropical regions and highlight distinct environmental associations relevant to rural populations.
Demographic trends and gender dimorphism
The mean age of presentation in our study was 12.02 years, with a peak incidence in the 11–12-year age group. This finding is consistent with national and international literature. Saboo et al., in a large series from Southern India, reported a similar mean age of 12 years,[11] while Lambiase et al. reported a mean age of 13.8 years in an Italian cohort.[2] The disease is characteristically a condition of the first and second decades of life, with spontaneous resolution often seen after puberty.
A striking feature of VKC is its male preponderance. Our study observed a male-to-female ratio of 2.03:1. This is in close agreement with Singh et al., who reported a ratio of 2.5:1.[7] This gender disparity is hypothesized to be hormonal in origin; androgens are thought to promote pro-inflammatory pathways or lymphocyte proliferation, whereas estrogens and progesterone may exert a protective effect on the ocular surface immune system. This hypothesis is further supported by the observation that the gender gap often narrows in adult-onset cases or after puberty.
Seasonality and climatic influence
VKC is inextricably linked to climatic conditions. In our study, symptom exacerbation peaked in May. This corresponds to the onset of the hot, humid summer in Assam, characterized by high temperatures and increased pollen dispersion. This “summer surge” aligns with the classic tropical pattern of VKC, distinguishing it from the purely spring-time (vernal) exacerbations seen in temperate European climates.[1] The combination of high humidity and heat likely facilitates the proliferation of fungal spores and house dust mites, while simultaneously inducing vasodilation of the conjunctival vasculature, thereby delivering more inflammatory mediators to the ocular surface.
Predominance of the limbal phenotype
One of the most significant clinical findings in our study was the overwhelming dominance of the Limbal variant (72%), followed by the palpebral and mixed types. This stands in contrast to western studies, such as those by Bonini et al.,[1] and Leonardi et al.,[3] which often report a higher prevalence of the palpebral (tarsal) form in temperate zones. However, our findings resonate with other studies from tropical belts, including reports by Singh et al.,[7] and Saboo et al.[11]
The predilection for limbal involvement in tropical regions like North-East India may be attributed to higher exposure to ultraviolet (UV) radiation. Solar UV radiation is a known trigger that can alter the antigenicity of conjunctival proteins or directly stimulate limbal mast cells and fibroblasts. The intense gelatinous hypertrophy and Horner–Trantas dots seen in our patients represent a chronic, cell-mediated immune response specifically localized to the limbal stem cell niche.
Environmental risk factors: The biomass connection
Perhaps the most pivotal finding of this study is the strong association (P < 0.001) between VKC and the use of biomass fuels (firewood and kerosene) for cooking. We also observed a significant association (P < 0.001) with close animal contact. This aligns with recent epidemiological data from developing nations. For instance, studies from Ethiopia by Hayilu et al.,[9] and Alemayehu et al.,[10] reported adjusted odds ratios of 6.25 for children exposed to kerosene or firewood smoke.
The mechanism by which biomass smoke exacerbates VKC is likely twofold:
Direct Toxicity: Smoke from firewood releases Particulate Matter (PM2.5 and PM10), carbon monoxide, and volatile organic compounds. These pollutants are directly toxic to the ocular surface epithelium, disrupting the mucin layer of the tear film. A compromised tear film barrier allows for easier penetration of aeroallergens, thereby lowering the threshold for sensitization
Non-specific Hyperreactivity: Chronic exposure to smoke induces a state of non-specific conjunctival hyperreactivity. In this state, the conjunctiva reacts more aggressively not just to specific allergens (like pollen) but also to non-specific irritants.
In addition, our study noted associations with close animal contact and dust exposure, which serve as reservoirs for mites and dander, respectively. This highlights that in rural settings, “avoidance therapy” – the cornerstone of allergic management – is often challenging due to the ubiquitous nature of these triggers in the patient’s living environment.
Limitations
The study has inherent limitations. As a hospital-based study, there is a potential for selection bias toward more severe cases, as mild cases may not seek tertiary care. Hence, the study could not classify disease severity, which limits clinical correlations with risk factors. Consequently, the prevalence of complications may be higher in our cohort than in the general community. Furthermore, specific IgE testing or skin prick testing was not universally performed due to resource constraints, limiting our ability to identify specific offending allergens.
CONCLUSION
This study highlights that VKC in the rural population of North-East India is a significant ocular morbidity affecting predominantly male children and adolescents. The disease in this region is characterized by a high prevalence of the Limbal phenotype and a distinct seasonal exacerbation during the hot, humid months of summer.
Crucially, our findings establish a strong link between VKC severity and rural environmental factors, specifically the use of biomass fuels (firewood and kerosene) for indoor cooking and close animal contact. This suggests that indoor air pollution acts as a potent modifiable risk factor that may lower the threshold for allergic sensitization or exacerbate existing ocular surface inflammation.
Management of VKC in this demographic cannot rely solely on pharmacological intervention. Public health initiatives must focus on parental counseling regarding “avoidance therapy,” which should include minimizing exposure to indoor smoke and close animal contact. Future community-based studies are warranted to further quantify the impact of indoor air quality on ocular allergies and to investigate genetic susceptibility patterns specific to the North-East Indian population.
Acknowledgment:
We would like to express our sincere gratitude to the Principal and Superintendent of the tertiary care teaching hospital situated in a rural region of North-East India for permitting us to conduct this study. We are deeply thankful to the faculty members, residents, optometrists, and staff of the Department of Ophthalmology for their assistance in data collection and patient evaluation. Most importantly, we extend our heartfelt thanks to the children and their parents who participated in this study for their cooperation and patience during the examination process.
Author contributions:
JB, ID: Conceptualization, methodology, validation, writing - review & editing, data curation; JB: Formal analysis, visualization, supervision; ID: Software, investigation, writing - original draft. All authors provided final approval to the work.
Ethical approval:
The research/study was approved by the Institutional Ethics Committee, Gauhati Medical College and Hospital, Guwahati, number MC/190/2007/Pt11/Jun 2022/29, dated July 25, 2022.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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