An enhanced model for environmental dry eye: Exploring pathological features and underlying factors

Area of Science:

• Ophthalmology and Vision Science
• Environmental Health
• Animal Models

Background:

• Prolonged visual tasks can lead to dry eye disease (DED), often associated with visual fatigue.
• Existing animal models for DED, such as the 'jogging board' model, have limitations in replicating the etiology of visually demanding activities.
• There is a need for an enhanced environmental dry eye (EDE) model that accurately mimics the conditions leading to DED from prolonged visual fatigue.

Purpose of the Study:

• To develop and validate an enhanced environmental dry eye (EDE) model.
• To investigate the pathological features of dry eye induced by prolonged visual fatigue using the new model.
• To compare the efficacy of this novel model against traditional dry eye models.

Main Methods:

• Forty Wistar rats were divided into control and model groups.
• The model group was exposed to frontal airflow (2-4 m/s) for 7.5 hours daily on a suspended cylindrical wire mesh frame for 14 days.
• Assessments included blink frequency, tear secretion, tear film breakup time (BUT), fluorescein staining, corneal histology, ultrastructure, and inflammatory cytokine (IL-1β, TNF-α, MMP-9, IL-6, IFN-γ, caspase-3) expression in tears and corneal tissues.

Main Results:

• The model group showed significantly reduced blink frequency, tear secretion, and BUT, alongside increased fluorescein staining compared to controls (P < 0.001).
• Histological and electron microscopy revealed corneal epithelial thickening, disorganized cells, surface defects, and rough surfaces in the model group.
• Elevated levels of IL-1β, TNF-α in tears and upregulated mRNA/protein expression of MMP-9, TNF-α, IL-1β, caspase-3, IL-6, and IFN-γ were observed in the model group's corneal tissues.

Conclusions:

• The modified 'wire-meshing cylindrical board' model effectively simulates the etiology of prolonged visual fatigue and overcomes limitations of previous models.
• This EDE model demonstrates high relevance to DED from prolonged visual tasks, with a high success rate and practical applicability.
• The model is simple, practical, and easily replicable, making it suitable for further research and clinical applications in prolonged visual fatigue-related DED.