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Allergic conjunctivitis: symptoms, treatment
Last reviewed: 05.07.2025
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Allergic conjunctivitis is an acute, recurrent or chronic inflammation of the conjunctiva caused by allergens. Symptoms include itching, lacrimation, discharge, and conjunctival hyperemia. Diagnosis is clinical. Treatment is with topical antihistamines and mast cell stabilizers.
Allergic conjunctivitis has the following synonyms: atopic conjunctivitis; atopic keratoconjunctivitis; hay fever; perennial allergic conjunctivitis; seasonal allergic conjunctivitis; vernal keratoconjunctivitis.
[ What causes allergic conjunctivitis?
Allergic conjunctivitis develops as a type I hypersensitivity reaction to a specific antigen.
Seasonal allergic conjunctivitis (hay fever conjunctivitis) is associated with tree, grass, or tobacco pollen in the air. It tends to peak during the spring and late summer. It subsides during the winter months, consistent with the life cycle of the plants that cause allergic conjunctivitis.
Chronic allergic conjunctivitis (atopic conjunctivitis, atopic keratoconjunctivitis) is associated with dust particles, animal dander, and other non-seasonal allergens. These allergens, especially household allergens, tend to cause symptoms year-round.
Vernal keratoconjunctivitis is the most severe type of conjunctivitis and is probably allergic in origin. It occurs most often in males aged 5 to 20 years who also have eczema, asthma, or seasonal allergies. Vernal conjunctivitis usually appears each spring and subsides in the winter. It often resolves as the child gets older.
Symptoms of allergic conjunctivitis
Patients complain of intense itching of both eyes, conjunctival redness, photophobia, swelling of the eyelids, and watery or viscous discharge. Concomitant rhinitis is common. Many patients have other atopic diseases such as eczema, allergic rhinitis, or asthma.
Symptoms of allergic conjunctivitis include conjunctival edema, hyperemia, and often a tenacious mucous discharge containing numerous eosinophils. The bulbar conjunctiva may appear clear, bluish, and thickened. Chemosis and characteristic flaccid edema of the lower eyelid are common. In seasonal and chronic allergic conjunctivitis, the fine papillae of the upper eyelid conjunctiva have a velvety appearance. Chronic itching may lead to chronic lid rubbing, periocular hyperpigmentation, and dermatitis.
In the most severe forms of chronic allergic conjunctivitis, large papillae on the tarsal conjunctiva, conjunctival scarring, corneal neovascularization and scarring with varying degrees of visual acuity loss may be observed.
Vernal keratoconjunctivitis usually involves the upper lid conjunctiva, but sometimes the bulbar conjunctiva is also affected. In the palpebral form, the superior tarsal conjunctiva has mainly rectangular, dense, flattened, closely spaced, pale pink to grayish cobblestone-like papillae. The uninvolved tarsal conjunctiva is milky white. In the ocular "limbal" form, the conjunctiva around the cornea becomes hypertrophied and grayish. Sometimes a rounded corneal epithelial defect develops, causing pain and increased photophobia. Symptoms usually disappear in the cold months of the year and become less pronounced with age.
How to recognize allergic conjunctivitis?
The diagnosis is usually made clinically. Conjunctival scrapings, which may be taken from the superior or inferior tarsal conjunctiva, show eosinophils; however, this testing is rarely indicated.
How is allergic conjunctivitis treated?
Avoidance of allergens and use of tear substitutes may relieve symptoms; specific immunotherapy is sometimes helpful. Ophthalmic preparations containing a combination of antihistamines and vasoconstrictors (eg, naphazoline/pheniramine) are useful in uncomplicated cases. If these drugs are insufficient, antihistamines (eg, olopatadine, ketotifen), NSAIDs (eg, ketorolac), or mast cell stabilizers (eg, pemirolast, nedocromil) may be used alone or in combination. In persistent cases, topical glucocorticoids (eg, loteprednol drops, 0.1% fluorometholone, 0.12% to 1% prednisolone acetate twice daily) may be helpful. Because topical glucocorticoids may promote ocular infection with herpes simplex virus, possibly a leading cause of corneal ulceration and perforation, and may lead to glaucoma and possibly cataracts with prolonged use, their use should be prescribed and monitored by an ophthalmologist. Topical cyclosporine is indicated where glucocorticoids are needed but cannot be used.
Seasonal allergic conjunctivitis requires less medication, and intermittent use of topical glucocorticoids is possible.