Allergic conjunctivitis is the inflammatory process of the conjunctiva of immunological origin as an excessive response to substances that irritate and inflame it. Allergic conjunctivitis is an inflammation of the conjunctiva (the membrane that lines the ocular surface and the inside of the eyelids) caused by an excessive response of our body to an external agent (allergen). Allergic conjunctivitis affects 25% of the general population and can occur alone or accompanied by other allergic diseases such as rhinitis, eczema or asthmatic bronchitis. When the allergen comes in contact with the eye, the immune system triggers an allergic inflammatory response that activates eosinophils and mast cells and others that release IgE and histamine, which are responsible for the appearance of the characteristic symptoms.

Causes and Symptoms

Main Causes for allergies are:

  • Pollen of flowers and grasses
  • Dust mites
  • Cosmetics
  • Animal hair
  • Antibiotics: penicillin, sulfonamides, streptomycin, ...

Allergic conjunctivitis can be seasonal (some months of the year) or perennial (throughout the year) and is usually bilateral and is characterized by symptoms of:

  • Itching
  • Red eye
  • Lachrymation
  • Watery mucosal discharge
  • Eyelid edema
  • Photophobia (discomfort with light)
  • Foreign body sensation


The diagnosis of allergic conjunctivitis is mainly made by a clinical examination of the conjunctiva finding the redness and the presence of papillae in the tarsal conjunctiva using the slit lamp, but the suspicion is based mainly on the analysis of the characteristic symptomatology referred by the patient, especially the itching accompanied by tearing.

In the most severe cases, it may be useful to carry out immunological studies to try to establish the possible allergens and the type of response they can generate in the patient by making studies of immunoglobulins, eosinophils and skin tests.


It is aimed at the relief of symptoms and control of the inflammatory response. Initially avoid rubbing the eyes and use cold compresses as many times as necessary. When it is required, the medical treatment must also be started using substances that make it possible to wash or dilute the allergen, such as artificial tears. In addition, management can be initiated with drugs that regulate the inflammatory and immunological response such as topical antiallergics ranging from sodium cromoglycate, olopatadine, bepotastine besilate, and others to the use of topical steroids that should only be formulated and controlled by the ophthalmologist. It should be remembered that in the allergic process there may be an early phase in which the main mediator is histamine and therefore drugs that inhibit or block histamine are very useful, but then there may be a late phase in which mediators are other substances such as leukotrienes, prostaglandins, platelet inhibiting factors and cytokines among others; then in these cases other drugs are more useful, such as dual action antiallergics that block not only the release of histamine but also the inflammatory cascade with the mediators mentioned. Normalmente no se recomienda el uso de antihistamínicos o antialérgicos sistémicos pues es poco el efecto sobre el ojo y si pueden producir resequedad y empeorar los síntomas.

It is very important to prevent Allergic Conjunctivitis trying to establish that triggers in each case in particular and thus avoid exposure to the allergen.

  1. 2016-2017 Basic and Clinical Science Course, Section 8, External Diseases and Cornea, Print ISBN: 978-1-61525-735-5