Allergic conjunctivitis

What is allergic conjunctivitis

Allergic conjunctivitis is an inflammation of the eyes due to hypersensitivity to certain external agents, called allergens, which cause an allergic reaction, whose symptoms affect in particular the conjunctiva, or the thin membrane that covers the eyeball and the inner surface of the eyelid.

It can occur in an acute form, as in the case of grass pollen allergy, the most common form among allergic conjunctivitis, or chronic, with less severe but more lasting symptoms.

Since its appearance occurs in response to the presence of allergens, it is distinguished from viral and bacterial conjunctivitis, which are caused by infections.

Redness and itching in the eyes are the main symptoms and can last from a few minutes to a few days. Other manifestations typically related to this disorder are:

• swelling of the eyelids
• burning, pain and discomfort in the eyes
• feeling like a foreign body in your eye, like grains of sand
• hypersensitivity to light, which in severe forms results in photophobia
• Persistent tearing
• secretion of a whitish and filamentous liquid.

Normally, allergic conjunctivitis involves a pharmacological treatment that resolves the symptoms in a short time; Only in the most serious cases can it worsen, coming to cause an inflammation of the skin called eyelid dermatitis, or a lesion of the cornea called corneal ulcer, resulting in eye injuries and blurred vision.

Causes of allergic conjunctivitis: why the eyes itch

The causes of an allergic reaction in the eyes can be varied. In fact, precisely according to the triggering cause, different forms of allergic conjunctivitis are distinguished:

• spring or seasonal allergic conjunctivitis, associated with rhinitis (the so-called hay fever) and due to pollen of some plants; It usually disappears in winter and exacerbates in spring, but can also occur in summer or early autumn, depending on the life cycle of the plant causing the allergic reaction.
• perennial allergic conjunctivitis, caused by mold, pet dander, dust mites, etc., which can cause symptoms throughout the year, regardless of the season
• allergic contact conjunctivitis, which arises as a result of the use of certain types of eye drops, cosmetics, detergents, etc.
• gigantopapillary allergic conjunctivitis, which causes inflammation of the inner surface of the eyelid and is generally due to the use of contact lenses or eye prostheses
• atopic allergic conjunctivitis, typical of young males; The causes are not fully known, but it is often related to other disorders such as dermatitis and eczema.

All these allergic forms cause redness, itching and burning and suffer mainly in subjects who already have other allergic symptoms, such as atopic dermatitis, asthma and allergic rhinitis.

In all forms of allergic conjunctivitis, symptoms are caused by an abnormal response of the immune system to a foreign substance, which is mistakenly identified as harmful to the body. When allergens come into contact with the eye, the immune system produces IgE antibodies, which stimulate mast cells to produce histamine in particular, the main mediator of the allergic reaction. Eye itching, redness and activation of the tear duct are consequences of this mechanism, as well as any other disorders that may affect the nasal mucosa, respiratory tract and skin.

It should also be noted that, given the high sensitivity to light of allergy sufferers, exposure to sunlight is a trigger for acute conjunctivitis.

Remedies for allergic conjunctivitis

The diagnosis of allergic conjunctivitis is made by the specialist following an eye examination. The doctor examines the patient’s eyes, especially the conjunctival area, and checks the state of inflammation, the presence of skin lesions and symptoms such as dilation of the blood vessels of the eyeball.

The intervention of the ophthalmologist and the execution of specific laboratory tests are fundamental steps to accurately determine the causes of the problem and distinguish allergic reactions from infectious forms or other diseases involving the eye, thus identifying the most suitable treatment for conjunctivitis for the individual case.

Contact lens wearers should also discontinue use until symptoms resolve to prevent inflammation from escalating into injury in the eye.

The treatment of conjunctivitis foresees in the first place, if and when possible, to avoid any contact with the allergens responsible for the symptoms.

As far as pharmacological therapies are concerned, the administration of different types of drugs may be envisaged, such as:

• antihistamines to combat redness and itchy eyes, generally in the form of ointment or drops (eye drops), but also in tablets especially if associated with rhinitis
• Corticosteroid eye drops
• decongestants and vasoconstrictors to inhibit the action of blood vessels
• stabilizers of mast cells, i.e. the cells that produce the substances that trigger the allergic reaction, first of all histamine
• NSAIDs (nonsteroidal anti-inflammatory drugs), to reduce inflammation.

The use of corticosteroids, in particular, must take place under strict medical supervision and cannot be “self-prescribed”. Although cortisone has a powerful healing action even in the worst cases of conjunctivitis, it has numerous side effects. Among them, the most important are the increase in eye pressure, the risk of corneal perforation and the development of glaucoma or cataracts.

Another treatment option for allergy sufferers is immunotherapy. This type of treatment aims to lead the body to develop a certain degree of tolerance to allergens. Desensitization therapy should be administered when the allergy is not in the acute phase. In the case of chronic form, however, this treatment is often not completely decisive.

To reduce swelling and inflammation, so-called artificial tears or chamomile compresses can also be useful. These remedies may partially relieve the symptoms, but they are not an effective cure for the problem.

In case of ascertained conjunctivitis, it is also necessary to follow some precautions:

• wash your hands frequently, especially before touching your eyes
• Do not rub your eyes forcefully
• Do not use contact lenses
• avoid exposure to sunlight and wear sunglasses with ultraviolet filters
• Do not wear makeup until symptoms resolve (and, in general, use hypoallergenic cosmetics).

These indications apply even more in the treatment of allergic children, who must not touch their eyes with dirty hands even in case of intense itching, must follow a balanced diet and must be protected from smoke and sunlight.

How to prevent allergic conjunctivitis

Prevention of allergic conjunctivitis, like its treatment, is possible in the first place by determining what the triggering agent is and reducing contact with it as much as possible.

If the allergy is due to substances such as makeup or contact lenses, it will be sufficient to avoid their use, while in case of seasonal allergic conjunctivitis in spring the patient can adopt the following strategies:

• avoid frequenting meadows, fields, parks and woods
• Keep your home windows and car windows closed and use air conditioners with pollen filters
• Wash your hair once you get home, as it may retain allergens.

To escape pollen allergy it is also necessary to know the flowering period of the “offending” plants. During the months most at risk, additional avoidance strategies may be envisaged, such as the use of masks on bicycles or motorcycles and protective sunglasses, or antihistamine eye drops, taken as a preventive measure before the start of flowering.

In the event of a perennial allergic conjunctivitis caused by dust or animal hair, however, to prevent allergic reactions you will have to create a protected home environment. The main expedients are:

• ventilate your home often
• eliminate hard-to-wash furnishings that facilitate the accumulation of mites and hair, such as carpets, draperies, carpets and upholstered sofas, but also open bookcases, dried flowers and wallpaper
• pay particular attention to the bedroom, changing and washing linen often (in case of allergy to mites, at temperatures above 60 ° C)
• use the vacuum cleaner often, preferably equipped with a special HEPA filter (High-Efficiency Particulate Air).