What is eye allergy
Eye allergies are inflammatory conditions affecting the visual apparatusmainly the conjunctiva. They occur most frequently in individuals who are particularly sensitive to external substances, the allergens: usually harmless molecules that can only trigger an excessive and uncontrolled immune response in some people. Allergies affecting the eyes affect approximately 10% -20% of people worldwide and, if neglected, can have a negative impact on quality of life. Among other things, they are often the cause of school and work absenteeism.
Early diagnosis, preventive measures and timely treatment can reduce the risk of recurrence as well as the possibility of complications.
Common forms of ocular allergies
The conjunctivitis seasonal allergy (SAC) and the Perennial allergic conjunctivitis (CAP) are the most common forms. The first, it arises during spring and/or summer and is triggered by the presence of pollen in the air, generally of grasses. SAC is often also associated with significant symptoms affecting the nasal passages, and in this case we speak of rhino-conjunctivitis.
The second, on the other hand, does not follow a defined seasonality and can occur at all times of the year. The allergens responsible for this form of allergy can be different: dust mites, pet hair or the presence of fungal spores and mould.
Both forms of conjunctivitis lead to a reaction of immediate hypersensitivity type I involving a particular class of antibodies, E-type immunoglobulins, which, following mast cell degranulation, induce the release of histamine, responsible for the initial phase of the allergic response and the activation of inflammatory mechanisms.
Symptoms
The symptomatology of allergic conjunctivitis varies according to the type and/or intensity with which they occur. The most common symptoms include:
-pruritus;
-eye reddening;
-eyelid swelling;
-secretion of mucus;
-lacrimation;
-bruising.
Who is at risk?
In general, all individuals can, during the course of their lives, suffer from allergic conjunctivitis, although these occur more frequently in children and adolescentsas well as in individuals suffering from asthma or rhinitis.
Rare ocular allergic forms
Less common ocular allergic forms include spring keratoconjunctivitis or Vernal (Vernal kerato-conguntivitis, VKC)atopic keratoconjunctivitis (atopic kerato-conjunctivitis, AVK)contact dermoconjunctivitis and gigantopapillary conjunctivitis (giant papillary conjunctivitis, GPC). These allergic forms, unlike common conjunctivitis, trigger both immediate and delayed hypersensitivity, the latter being responsible for the chronicity of the inflammatory condition.
LA VKC is considered a rare condition with an as yet unclear aetiology, affecting both eyes. This results in a fairly severe clinical condition, characterised by a chronic inflammatory condition, with a flare-up period during the spring season, involving both the cornea and conjunctiva. VKC affects males more frequently if it occurs during adolescence; women, if it appears in adulthood; and if it occurs during the first ten years of life, it tends to disappear spontaneously. Symptoms associated with this severe allergic form are, in addition to the common ones, photophobia, the sensation of a foreign body, blurred vision, intense mucus production and the presence of mucous eversions of the conjunctiva.
The AVK is a form of chronic ocular allergy that in some cases can lead to blindness. This form of allergy, which occurs during adolescence or adulthood, is many times associated with other diseases such as blepharoconjunctivitis or herpes simplex virus infections. The symptoms overlap with those of other allergic conjunctivitis, but with a greater severity. In addition, the AVK can lead to complications such as retinal detachment.
The contact dermatoconjunctivitis, as its name implies, is an allergic form that affects both the eyes and the skin. It arises following contact with the skin or eyelids of certain substances or products such as lcontact lenses, cosmetics or make-up tools. For this reason, it occurs more in women and the symptoms are similar to other forms of allergy.
The GPCFinally, it is an inflammatory condition associated with frequent wear of soft, semi-rigid or rigid contact lenses or arises as a result of mechanical trauma combined with a hypersensitivity reaction.
Diagnosis of eye allergy
The diagnosis of different forms of ocular allergies always starts with a acomprehensive namnesi and a careful assessment of symptoms complaining patient and of signs visible to the eye. Burning, Itching, redness of the eyes are symptoms usually associated with common allergic conjunctivitis; photophobia, corneal ulcers, eye pain or loss of vision, on the other hand, suggest more severe allergic forms. The ophthalmologist will make the definitive diagnosis and prescribe the most appropriate treatment.
Hints of treatment
Intervention strategies to combat ocular allergies involve, first of all, removing the agents that cause them. For less severe forms of allergy, the use of artificial tears, antihistamine lubricants and membrane stabilisersIn more severe forms, the specialist will prescribe the appropriate pharmacological treatment, which generally involves the administration of corticosteroids and non-steroidal anti-inflammatory drugs.
Prevention
The prevention through the adoption of a few small measures is possible, especially for allergic forms associated with seasonality. As a first step, if it is spring or summer conjunctivitis, it is good to protecting the eyes using sunglass lenses and instill regularly using lubricants or artificial tears so as to prevent allergens from coming into contact with the ocular surface as much as possible.
In addition, efforts should be made to reduce exposure to the pollen avoiding standing for too long in windy areas. Changing sheets, pillows, blankets and vacuuming frequently may help reduce the concentration of allergens that can inevitably accumulate.
Sources:
–Allergic eye disease. Darshak S Patel DS et al. BMJ, 359:j4706 (2017)
–Epidemiological trends of allergic diseases in adolescents. Silvia de Souza Campos Fernandes. J Bras Pneumol, 43(5):368-372 (2017)
Dr. Carmelo Chines
Direttore responsabile
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