(See also Overview of Conjunctivitis Overview of Conjunctivitis Conjunctival inflammation typically results from infection, allergy, or irritation. Symptoms are conjunctival hyperemia and ocular discharge and, depending on the etiology, discomfort and itching... read more .)
Etiology of Allergic Conjunctivitis
Allergic conjunctivitis is due to a type I hypersensitivity reaction Type I Allergic (including atopic) and other hypersensitivity disorders are inappropriate or exaggerated immune reactions to foreign antigens. Inappropriate immune reactions include those that are... read more to a specific antigen.
Seasonal allergic conjunctivitis (hay fever conjunctivitis) is caused by airborne mold spores or pollen of trees, grasses, or weeds. It tends to peak during the spring, late summer, or early fall and disappear during the winter months—corresponding to the life cycle of the causative plant.
Perennial allergic conjunctivitis (atopic conjunctivitis, atopic keratoconjunctivitis) is caused by dust mites, animal dander, and other nonseasonal allergens. These allergens, particularly those in the home, tend to cause symptoms year-round.
Vernal keratoconjunctivitis is a more severe type of conjunctivitis most likely allergic in origin. It is most common among males aged 5 to 20 years who also have eczema Atopic Dermatitis (Eczema) Atopic dermatitis is a chronic relapsing inflammatory skin disorder with a complex pathogenesis involving genetic susceptibility, immunologic and epidermal barrier dysfunction, and environmental... read more , asthma Asthma Asthma is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea... read more , or seasonal allergies. Vernal keratoconjunctivitis typically reappears each spring and subsides in the fall and winter. Many children outgrow the condition by early adulthood.
Symptoms and Signs of Allergic Conjunctivitis
Patients with allergic conjunctivitis report having
Bilateral mild to intense ocular itching
Photosensitivity (photophobia in severe cases)
Watery or stringy discharge
Concomitant rhinitis is common. Many patients have other atopic diseases, such as eczema Atopic Dermatitis (Eczema) Atopic dermatitis is a chronic relapsing inflammatory skin disorder with a complex pathogenesis involving genetic susceptibility, immunologic and epidermal barrier dysfunction, and environmental... read more , allergic rhinitis Allergic Rhinitis Allergic rhinitis is seasonal or perennial itching, sneezing, rhinorrhea, nasal congestion, and sometimes conjunctivitis, caused by exposure to pollens or other allergens. Diagnosis is by history... read more , or asthma Asthma Asthma is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea... read more .
Findings characteristically include conjunctival edema and hyperemia and a discharge. The bulbar conjunctiva may appear translucent, bluish, and thickened. Chemosis and a characteristic dermatoblepharitis with hyperemia, edema and lichenification of the medial upper first and then lower eyelid, are common. Chronic itching can lead to chronic eyelid rubbing, periocular hyperpigmentation, and dermatoblepharitis.
Seasonal and perennial conjunctivitis
In people with seasonal and perennial conjunctivitis, fine papillae on the upper tarsal conjunctiva give it a velvety appearance. In more severe forms, larger tarsal conjunctival papillae, conjunctival scarring, corneal neovascularization, and corneal scarring with variable loss of visual acuity can occur.
Usually, the palpebral conjunctiva of the upper eyelid is involved, but the bulbar conjunctiva is sometimes affected. In the palpebral form, square, hard, flattened, closely packed, pale pink to grayish cobblestone papillae are present in the upper tarsal conjunctiva. The uninvolved bulbar conjunctiva is milky white. In the bulbar (limbal) form, the circumcorneal conjunctiva becomes hypertrophied and grayish. Discharge may be tenacious and mucoid, containing numerous eosinophils.
In 3 to 11% of patients, a corneal ulcer Corneal Ulcer A corneal ulcer is a corneal epithelial defect with underlying inflammation usually due to invasion by bacteria, fungi, viruses, or Acanthamoeba. It can be initiated by mechanical trauma... read more develops, causing pain and increased photophobia. Other corneal changes (eg, central plaques) and white limbal deposits of eosinophils (Horner-Trantas dots) may be seen.
Diagnosis of Allergic Conjunctivitis
Diagnosis of conjunctivitis and differentiation between bacterial Acute Bacterial Conjunctivitis Acute conjunctivitis can be caused by numerous bacteria. Symptoms are hyperemia, lacrimation, irritation, and discharge. Diagnosis is clinical. Treatment is with topical antibiotics, augmented... read more , viral Viral Conjunctivitis Viral conjunctivitis is a highly contagious acute conjunctival infection usually caused by an adenovirus. Symptoms include irritation, photophobia, and watery discharge. Diagnosis is clinical... read more , and noninfectious conjunctivitis Allergic Conjunctivitis Allergic conjunctivitis is an acute, intermittent, or chronic conjunctival inflammation usually caused by airborne allergens. Symptoms include itching, lacrimation, discharge, and conjunctival... read more (see table Differentiating Features in Acute Conjunctivitis Diagnosis ) are usually clinical. In allergic conjunctivitis, eosinophils are present in conjunctival scrapings, which may be taken from the lower or upper tarsal conjunctiva; however, such testing is rarely indicated.
Treatment of Allergic Conjunctivitis
Topical antihistamines, nonsteroidal anti-inflammatory drugs, mast cell stabilizers, or a combination
Topical corticosteroids or cyclosporine for recalcitrant cases
Sometimes, oral antihistamines
Avoidance of known allergens and use of cold compresses and tear supplements can reduce symptoms of allergic conjunctivitis; antigen desensitization is occasionally helpful. Topical over-the-counter antihistamines (eg, ketotifen) are useful for mild cases. If these drugs are insufficient, topical prescription antihistamines (eg, olopatadine, bepotastine, azelastine, cetirizine), mast cell stabilizers (eg, nedocromil, cromolyn), or nonsteroidal anti-inflammatory drugs (eg, ketorolac) can be used separately or in combination. Topical corticosteroids (eg, loteprednol, fluorometholone 0.1%, prednisolone acetate 0.12% to 1% drops 3 times a day) can be useful in recalcitrant cases or when quick relief of symptoms is important. Because topical corticosteroids can lead to a flare-up of latent ocular herpes simplex virus infections Herpes Simplex Keratitis Herpes simplex keratitis is corneal infection with herpes simplex virus. It may involve the iris. Symptoms and signs include foreign body sensation, lacrimation, photophobia, and conjunctival... read more , possibly leading to corneal ulceration and perforation and, with long-term use, to glaucoma Overview of Glaucoma Glaucomas are a group of eye disorders characterized by progressive optic nerve damage in which an important part is a relative increase in intraocular pressure (IOP) that can lead to irreversible... read more and possibly cataracts Cataract A cataract is a congenital or degenerative opacity of the lens. The main symptom is gradual, painless vision blurring. Diagnosis is by ophthalmoscopy and slit-lamp examination. Treatment is... read more , their use should be initiated and monitored by an ophthalmologist. Topical cyclosporine drops may be helpful. Corticosteroid or tacrolimus ointment applied to the skin is very effective in the treatment of eyelid atopic dermatitis Atopic Dermatitis (Eczema) Atopic dermatitis is a chronic relapsing inflammatory skin disorder with a complex pathogenesis involving genetic susceptibility, immunologic and epidermal barrier dysfunction, and environmental... read more . Oral antihistamines (eg, fexofenadine, cetirizine, or hydroxyzine) can be helpful, especially when patients experience other allergic symptoms (eg, rhinorrhea).
Seasonal allergic conjunctivitis is less likely to require multiple drugs or intermittent topical corticosteroids.
Allergic conjunctivitis is usually caused by airborne allergens and can be seasonal or perennial.
Symptoms tend to include itching, eyelid edema, stringy or watery discharge, and sometimes a history of seasonal recurrence.
Diagnosis is usually clinical.
Treatment includes tear supplements and topical drugs (usually antihistamines, vasoconstrictors, nonsteroidal anti-inflammatory drugs, mast cell stabilizers, or a combination).