Ocular allergies: reactions of the immune system caused by foreign substances (antigens) with which the eye has already been in contact and to which it is therefore already "sensitised".
Indeed, when eyes are exposed to allergens, antibodies are produced. If the allergens come into contact again with the antibodies present in the conjunctiva, an allergic reaction occurs, for which inflammatory chemical substances (such as histamines) are released from the cells, causing the symptoms of allergic conjunctivitis.
The most common ocular allergy is seasonal and perennial conjunctivitis, which affects young people and adults of all ages. The seasonal form is commonly associated with rhinitis and is characterised, in the period in which allergens sensitising the subject itself are present in the environment, typical symptoms include: itching, hyperaemia (redness), tearing, mild eyelid edema (swelling of the eyelids). In case of allergens with no particular seasonality (such as animal epithelia or some moulds) seasonal conjunctivitis presents itself, however, as an occasional form of short duration. It is considered perennial conjunctivitis if the symptoms are persistent or chronic. In rare cases the cornea may be involved: this is called "keratoconjunctivitis", also characterised by photophobia (eye sensitivity to light) and filamentous and viscose secretions.
The most common symptoms of ocular allergies are itching; hyperaemia (redness), tearing, mild eyelid edema (swelling of the eyelids). In severe cases (keratoconjunctivitis) photophobia (eye sensitivity to light) and filamentous and viscous secretions are also present.
The first step is to remove the allergen that causes the allergy.
The basic treatment of all forms of allergic conjunctivitis involves the use of artificial tears, decongestants, membrane stabilisers, antihistamines or, in more severe forms, anti-inflammatories, above all corticosteroids.
The use of allergy vaccines can be considered in cases of recurrent ocular allergies in association with asthma and rhinitis.