Allergic Conjunctivitis
Overview
Allergic conjunctivitis is an inflammation of the conjunctiva caused by allergic reactions to environmental allergens. It is a common condition that can affect people of all ages, leading to significant discomfort and impairment of daily activities.
Etiology
- Allergens: Pollen, dust mites, animal dander, mold, smoke, and other environmental pollutants.
- Types:
- Seasonal allergic conjunctivitis (SAC): Linked to seasonal allergens like pollen.
- Perennial allergic conjunctivitis (PAC): Present year-round due to non-seasonal allergens like dust mites or pet dander.
- Vernal keratoconjunctivitis (VKC): More severe, often affects young boys, with seasonal exacerbation.
- Atopic keratoconjunctivitis (AKC): Associated with atopic dermatitis, can lead to chronic symptoms and complications.
Pathophysiology
- Immune Response: Allergen exposure leads to IgE-mediated hypersensitivity. Mast cell degranulation releases histamine and other inflammatory mediators, causing symptoms.
Clinical Features
- Symptoms: Itching (hallmark symptom), redness, watery discharge, burning sensation, swollen eyelids.
- Signs: Conjunctival hyperemia, chemosis, eyelid edema, papillary hypertrophy on the tarsal conjunctiva.
- Differential Diagnosis: Infectious conjunctivitis, dry eye syndrome, blepharitis, and other causes of red eye.
Diagnosis
- History: Detailed history of allergen exposure, symptom timing (seasonal vs. perennial), personal or family history of atopy.
- Physical Examination: Inspection for signs of conjunctival inflammation, eyelid changes, and corneal involvement.
- Investigations: Rarely needed; allergen testing (skin prick tests, specific IgE) may be useful in recurrent or severe cases.
Management
- Avoidance of Allergens: Minimize exposure to known allergens (e.g., using air purifiers, keeping windows closed during high pollen seasons, frequent cleaning to reduce dust mites).
- Pharmacotherapy:
- Antihistamines: Oral or topical (e.g., olopatadine, ketotifen) to reduce itching and inflammation.
- Mast Cell Stabilizers: (e.g., cromolyn sodium, lodoxamide) useful for long-term control.
- Dual-action Agents: (e.g., olopatadine, ketotifen) combining antihistamine and mast cell stabilization properties.
- Decongestants: (e.g., naphazoline) for short-term use; prolonged use can cause rebound hyperemia.
- Corticosteroids: (e.g., loteprednol, prednisolone) for severe cases; use with caution due to potential side effects (glaucoma, cataract formation).
- Immunomodulators: (e.g., cyclosporine A) in chronic, severe cases.
- Supportive Care: Cool compresses, lubricating eye drops (artificial tears) to provide symptomatic relief.
Follow-Up and Complications
- Follow-Up: Regular follow-up to monitor response to treatment and adjust management as needed.
- Complications: Chronic cases (especially VKC and AKC) can lead to corneal involvement (shield ulcers), scarring, vision impairment.
Patient Education
- Education: Inform patients about the chronic nature of the condition and the importance of adherence to treatment and allergen avoidance.
- Lifestyle Modifications: Encourage modifications to reduce allergen exposure at home and work.
Referral
- Indications for Referral: Severe, unresponsive cases, complications like corneal involvement, need for immunomodulatory therapy.