DefinitionAllergic conjunctivitis occurs when the clear layer of tissue lining the eyelids and covering the white of the eye (conjunctiva) become swollen or inflamed due to a reaction to pollen, dander, mold, or other allergy-causing substances.
Alternative NamesConjunctivitis - allergic seasonal/perennial; Atopic keratoconjunctivitis
Causes, incidence, and risk factorsWhen your eyes are exposed to anything to which you are allergic, histamine is released and the blood vessels in the conjunctiva become swollen. Reddening of the eyes develops quickly, along with itching and tearing.The pollens that cause symptoms vary from person to person and from area to area. Tiny, hard-to-see pollens that may cause hay fever include:GrassesRagweedTreesThe amount of pollen in the air can affect whether you develop symptoms. There is more likely to be increased amounts of pollen in the air on hot, dry, windy days. On cool, damp, rainy days most pollen is washed to the ground.Allergies tend to run in families, although they are not inherited in any obvious way. It is hard to know exactly how many people have allergies, because many different conditions are often lumped under the term allergy.
SymptomsSymptoms may be seasonal and can include:Intense itching or burning eyesPuffy eyelids, especially in the morningRed eyesStringy eye dischargeTearing (watery eyes)Widened (dilated) vessels in the clear tissue covering the white of the eye
Signs and testsYour health care provider may look for the following:Certain white blood cells, called eosinophilsSmall, raised bumps on the inside of the eyelids (papillary conjunctivitis)Positive skin test for suspected allergens on allergy tests
TreatmentThe best treatment is to avoid what causes your allergy symptoms. It may be impossible to avoid all of your triggers. However, you can often take steps to reduce your exposure to triggers such as:DustMoldPollenLubricating eye drops can help decrease symptoms. You can relieve discomfort by applying cool compresses to the eyes. Over-the-counter oral antihistamines can provide more relief. However, they can sometimes make the eyes dry. If home-care measures do not help, you may need treatment by a health care provider. This may include:Antihistamine or anti-inflammatory dropsMild eye steroid drops (for more severe reactions) You may also use eye drops that prevent certain white blood cells, called mast cells, from releasing histamine. These drops are given along with antihistamines for more severe symptoms. They work best if you take them before coming into contact with the allergen.
Expectations (prognosis)Treatment often relieves symptoms, but they can return if you continue to be exposed to the allergen.
ComplicationsThere are no serious complications, although discomfort is common.
Calling your health care providerCall for an appointment with your health care provider if you experience allergic conjunctivitis and it does not respond to over-the-counter treatment.
ReferencesHaq SM, Singh S, Song BJ, Trocme SD. Ocular allergic disorders. In: Tasman W, Jaeger EA, eds. Foundations of Clinical Ophthalmology. 2012 ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2012: vol 2, chap 30.Bielory L, Friedlaender MH. Allergic conjunctivitis. Immunol Allergy Clin North Am. 2008;28(1):43-58.Stock EL, Meisler DM. Vernal keratoconjunctivitis. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology On DVD-ROM. 1st ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2012:chap 9.