Allergy

Allergy is the body's defense syndrome against an allergen

Allergy is an exaggerated reaction of the immune system to a substance foreign to the body. The eye, in direct contact with the environment, is very often affected by allergic reactions, and this applies to the whole of the exposed area, since the eyelids and conjunctiva can be affected, sometimes complicating corneal damage. Ocular allergies are common (around 40-60% of allergy sufferers have ocular symptoms) and are often embarrassing for sufferers because they recur.¹⁻²⁻³

What are the main forms of ocular allergy?

Allergic conjunctivitis

The most common ocular allergy in both adults and children is allergic conjunctivitis⁴⁻⁵, which manifests itself as a hypersensitivity reaction to environmental allergens. To better understand this condition, we need to know that it involves the conjunctiva, i.e. the membrane surrounding the white of the eye².

There are different types of allergic conjunctivitis, with different symptoms:

Seasonal allergic conjunctivitis is a disease caused by hypersensitivity to certain pollens².
Allergic conjunctivitis predominates in spring and early summer. For the rest of the year, symptoms diminish or disappear. It is most often associated with allergic rhinitis⁴.
Permanent allergic conjunctivitis (perennial conjunctivitis) mainly affects adults. Its manifestations are constant with periods of recrudescence⁴. Household allergens are particularly implicated in this form of conjunctivitis.
Atopic conjunctivitis is also caused by a reaction to the environment, and manifests as general signs of atopy such as eczema or asthma².
Learn more about allergic conjunctivitis

Keratitis

Allergic keratoconjunctivitis is another form of ocular allergic reaction. Much less frequent, this type of allergy can be responsible for more severe eye damage.

Vernal keratoconjunctivitis, also known as children's spring conjunctivitis, is a form of severe allergic conjunctivitis in children. It mainly affects boys¹⁻²⁻³⁻⁴.
Like other forms of allergy, it is a hypersensitivity reaction to environmental factors, but genetic factors are also thought to be involved¹.

Eyelid allergies

Allergy can also manifest itself through eyelid involvement: most frequently, this is palpebral eczema, but it is common to find multiple pathological mechanisms responsible for chronic blepharitis (inflammation of the eyelids) in adults, among which allergy plays a key role¹⁻⁴.

The causes of eyelid allergies are many and varied.

There are also different methods of treating these allergies. In the first instance, contact with allergens should be avoided wherever possible; otherwise, local (eye drops) or general (oral) treatments may be prescribed by the ophthalmologist⁵⁻⁴.

Bibliography

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