What are the effects of allergic conjunctivitis on the eye?

Effects of Allergic Conjunctivitis on the Eye

Allergic conjunctivitis causes inflammation of the ocular surface resulting in itching, tearing, lid and conjunctival edema-redness, and photophobia, with potential progression to tissue remodeling and ocular surface damage in chronic severe cases. 1

Types of Allergic Conjunctivitis

Allergic conjunctivitis encompasses several distinct conditions:

1. Acute forms:

   • Seasonal allergic conjunctivitis (SAC)
   • Perennial allergic conjunctivitis (PAC)

2. Chronic forms:

   • Vernal keratoconjunctivitis (VKC)
   • Atopic keratoconjunctivitis (AKC)
   • Giant papillary conjunctivitis (GPC) 2

Pathophysiology

Allergic conjunctivitis primarily involves type 1 hypersensitivity reactions:

• Initial phase: IgE-mediated mast cell activation and degranulation
• Late-phase response: Infiltration of eosinophils and neutrophils
• Chronic disease: Tissue remodeling of the ocular surface 1

Clinical Effects on the Eye

Common Symptoms

• Itching (hallmark symptom)
• Tearing
• Redness
• Lid swelling
• Conjunctival edema
• Photophobia 1, 3

Physical Findings

• Conjunctival hyperemia
• Papillary reaction (especially in chronic forms)
• Follicular changes
• Mucous discharge
• Chemosis (conjunctival edema) 4

Complications in Chronic/Severe Forms

• Corneal involvement (especially in VKC)
• Corneal epithelial erosions
• Shield ulcers
• Neovascularization
• Vision impairment
• Tissue remodeling 1

Differential Effects by Subtype

Seasonal and Perennial Allergic Conjunctivitis

• Generally milder ocular surface effects
• Minimal long-term sequelae
• Often associated with rhinitis (allergic rhinoconjunctivitis) 4, 3

Vernal Keratoconjunctivitis

• More severe inflammation
• Giant papillae on tarsal conjunctiva
• Limbal infiltrates
• Corneal involvement with potential vision-threatening complications 4

Atopic Keratoconjunctivitis

• Chronic inflammation
• Lid eczema
• Conjunctival scarring
• Corneal neovascularization and scarring 2

Aggravating Factors

Several non-specific factors can exacerbate allergic conjunctivitis:

• Contact lens wear
• Local infections
• Ocular trauma
• Astigmatism
• Heterophoria
• Photosensitization 5

Diagnostic Considerations

The diagnosis is primarily clinical, based on:

• Characteristic symptoms (especially itching)
• Seasonal patterns
• Associated allergic conditions
• Response to antiallergic medications

In cases where IgE-mediated hypersensitivity assessment is inconclusive, a conjunctival allergen provocation test may be performed 4.

Impact on Quality of Life

Severe forms of allergic conjunctivitis can significantly impact quality of life:

• Discomfort and pain
• Visual disturbances
• Limitation of outdoor activities
• Sleep disturbances
• Psychological effects (anxiety, depression)
• Impaired school/work performance 1

Clinical Pitfalls

• Allergic conjunctivitis may be confused with dry eye syndrome, as symptoms can overlap
• Unilateral symptoms don't rule out allergic conjunctivitis, especially when non-specific factors are involved
• Chronic allergic conjunctivitis is often underdiagnosed and undertreated 5, 2
• Overuse of topical corticosteroids can lead to complications including cataracts and glaucoma 1