What is the best course of treatment for a patient with left eye irritation, itchiness, redness, and swelling without drainage, suspected to be allergic conjunctivitis?

Treatment of Allergic Conjunctivitis

Start with a dual-action topical antihistamine/mast cell stabilizer such as ketotifen or olopatadine as first-line therapy, applied twice daily to the affected eye. 1, 2

Immediate First-Line Treatment

• Prescribe ketotifen 0.025% ophthalmic solution, 1 drop in the affected eye twice daily (every 8-12 hours) as it provides rapid symptom relief within 30 minutes and is available over-the-counter 1, 2, 3
• Alternatively, use olopatadine 0.1%, epinastine, or azelastine—all dual-action agents with similar efficacy and rapid onset 1, 2
• These agents both treat acute symptoms immediately and prevent future episodes through mast cell stabilization, making them superior to single-mechanism drugs 1, 2

Essential Adjunctive Non-Pharmacological Measures

• Apply cold compresses to the affected eye for immediate symptomatic relief 1, 4
• Use refrigerated preservative-free artificial tears 4 times daily to dilute allergens and inflammatory mediators on the ocular surface 1, 2
• Store the dual-action eye drops in the refrigerator for additional cooling relief upon instillation 1
• Counsel the patient to avoid eye rubbing, as this worsens symptoms and can lead to keratoconus, especially in atopic patients 1

Escalation Strategy if Inadequate Response After 48 Hours

• Add loteprednol etabonate (low side-effect topical corticosteroid) for 1-2 weeks maximum if symptoms persist despite dual-action drops 1, 2
• This requires baseline intraocular pressure (IOP) measurement and periodic monitoring throughout use, plus pupillary dilation to evaluate for glaucoma and cataract formation 1, 2
• Never use topical corticosteroids as monotherapy—only as a brief adjunct to antihistamine therapy 1

Critical Pitfalls to Avoid

• Never use punctal plugs in allergic conjunctivitis as they prevent flushing of allergens and inflammatory mediators from the ocular surface 1
• Avoid oral antihistamines as primary treatment because they worsen dry eye syndrome and impair the tear film's protective barrier 1, 2, 4
• Do not use over-the-counter antihistamine/vasoconstrictor combinations (like naphazoline/pheniramine) for more than 10 days due to risk of rebound hyperemia (conjunctivitis medicamentosa) 1, 2
• Avoid topical antibiotics entirely—they provide no benefit for allergic disease, induce toxicity, and contribute to antibiotic resistance 1

When to Consider Severe/Refractory Disease Management

• If symptoms remain uncontrolled after dual-action drops plus a brief corticosteroid course, consider topical cyclosporine 0.05% at least 4 times daily or tacrolimus 1, 2
• These agents are particularly effective for vernal or atopic keratoconjunctivitis and allow for reduced corticosteroid use 1, 2
• Cyclosporine demonstrates reduction in signs and symptoms after 2 weeks of use 1, 2

Duration of Treatment

• Continue dual-action agents as long as allergen exposure persists—unlike corticosteroids or vasoconstrictors, these have no maximum treatment duration and are safe for extended use 1, 2
• The mast cell stabilizing properties make them suitable for chronic, ongoing treatment rather than just acute symptom management 2
• Reassess need at regular follow-up visits based on symptom control 1

Key Distinguishing Features Supporting This Diagnosis

• Itching is the most consistent and distinguishing sign of allergic conjunctivitis 5, 6
• The absence of discharge (as noted in this case) strongly supports allergic rather than bacterial etiology 5, 6
• Redness, swelling, and irritation without mattering or morning crusting further confirm allergic rather than infectious conjunctivitis 5, 6