The Role of Vitamin D in Corneal Epithelial Barrier Function, Ocular Microbiome, Ocular Inflammation, and Visual Acuity of Children With Allergic Conjunctivitis

Not Applicable

• Conditions: Allergic Conjunctivitis
• Interventions: Other: Vitamin D; Other: Placebo

• Registration Number: NCT05839938
• Lead Sponsor: China Medical University Hospital

Brief Summary

A double-blind study to evaluate the role of vitamin D in corneal epithelial barrier function, ocular microbiome, ocular inflammation, and visual acuity of children with allergic conjunctivitis.

Detailed Description

The prevalence of allergic conjunctivitis (AC) has rapidly increased in recent decades, resulting in a significant global public health concern. The ocular surface is a unique mucosal immune compartment in which immunological features act in concert to foster a tolerant microenvironment (immune privilege). The corneal epithelial barrier is the first line of defense that forms a protective barrier against pathogens, pollutants, and allergens. The ocular microbiota has a role in maintaining the homeostasis of the ocular surface and preservation of barrier function. Vitamin D functions as enforcing intercellular junctions and maintaining intestinal epithelial barrier integrity; metabolites from the gut microbiota may also regulate expression of vitamin D receptor (VDR). Low serum vitamin D levels have been shown to predispose to a variety of allergic disorders. A recent study shows that corneas contain vitamin D and VDR; vitamin D enhances corneal epithelial barrier function. However, research data of the role of vitamin D in ocular microenvironment of AC are insufficient and controversial. In recent research, the investigators found allergic inflammation of ocular surface weakened corneal epithelial barrier, modulated the signal pathway of retinal pigment epithelial cells, and enhanced scleral tissue remodeling, resulting in myopia in progression. However, there are few studies available to investigate the role of vitamin D in ocular surface microenvironment, ocular inflammation, and visual acuity in AC. Moreover, understanding the interaction of vitamin D, ocular microbiota, and ocular inflammation may provide a new target for the development of therapeutic interventions of ocular allergy and restore visual function.

Study Timeline

• Study Start: 2022-08-08
• Study First Submitted: 2023-04-21
• Study First Submitted QC: 2023-04-21
• Study First Posted: 2023-05-03
• Status Verified: 2024-06
• Last Update Submitted: 2024-06-30
• Last Update Posted: 2024-07-03
• Primary Completion: 2025-07-31
• Study Completion: 2025-07-31

Recruitment & Eligibility

• Status: ENROLLING_BY_INVITATION
• Sex: All
• Target Recruitment: 150

Inclusion Criteria

1. Children aged 6-18 years with allergic conjunctivitis (AC) diagnosed by ophthalmologists or allergists

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Exclusion Criteria

1. Previous eye surgery
2. Active eye infection
3. Any active inflammatory eye disease except AC
4. Systemic steroid use within 28 days of study

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Treatment group	Vitamin D	Vitamin D (2000IU/day) for 6 months
Control group	Placebo	placebo

Primary Outcome Measures

Name	Time	Method
Levels of vitamin D	Month 6	Vitamin D will be measured in a blood sample to follow the change from baseline in vitamin D level at month 6.
Microbiome	Month 6	Nasal, subconjunctival and anal swabs will be used to detect ocular surface, nasal and intestinal microbiome by using 16S rRNA sequencing, and to follow the change from baseline in microbiome at month 6.
Allergen-specific IgE	Month 0	Plasma allergen-specific IgE will be measured by BioIC ®.
Total IgE	Month 6	Plasma total IgE concentration will be measured by microparticle immunoassay (IMx analyzer, Abbott Laboratories, Abbott Park, IL) and ELISA to follow the change from baseline in total IgE at month 6.
Single nucleotide polymorphism of vitamin D receptor and vitamin D binding protein	Month 0	Single nucleotide polymorphism (SNP) genotyping will be performed in a blood sample by using TaqMan SNP genotyping assays.

Secondary Outcome Measures

Name	Time	Method
mini-Rhinoconjunctivitis Quality of Life Questionnaire (mini-RQLQ)	Month 0 to Month 6	mini-RQLQ is to measure a the level of severity of a set of symptoms of functional impairments due to rhinoconjunctivitis. 14 questions each range 0-6 (6 is most severe). Total range 0-84 (higher scores reflect lower quality of life.)

Trial Locations

Locations (1)

China Medical University Hospital; 🇨🇳 Taichung, Taiwan