Dr. Maria Benova: Allergic Conjunctivitis Can Lead to Irreversible Vision Damage

Allergic diseases have increased drastically over the past decades. Ocular allergy is one of the most common eye conditions encountered in clinical practice, faced by allergologists and ophthalmologists. This is highlighted by Dr. Mariya Benova, ophthalmologist at the Specialized Eye Clinic “PENTAGRAM”.

20% of the global population is affected by some form of allergy, with 40-60% of allergy patients also experiencing ocular symptoms. Nonetheless, allergic conjunctivitis often remains unrecognized and therefore inadequately treated. This is why efforts must be directed toward properly understanding the symptoms of ocular allergic diseases, selecting appropriate and timely therapy to avoid complications, and improving the quality of life for patients.

Dr. Benova, what is allergic conjunctivitis and who does it most commonly affect?

Allergic conjunctivitis is a disease with increasing prevalence that affects both children and adults. It significantly impacts the quality of life of these patients and can sometimes lead to irreversible vision damage. Various forms of the disease exist, some of which are allergen-induced, such as seasonal and perennial allergic conjunctivitis, giant papillary conjunctivitis, and contact allergic blepharoconjunctivitis, while others are not always associated with allergen exposure, such as vernal keratoconjunctivitis and atopic keratoconjunctivitis.

Allergic conjunctivitis is a group of diseases caused by a reaction of the eye, particularly the conjunctiva, to environmental allergens. They are common, affecting 10-20% of the population. The prevalence of allergies is increasing, and currently approximately 20% of the global population is affected by some form of allergy, with up to 40-60% of allergy patients also experiencing ocular symptoms.

The most widespread form of allergic conjunctivitis is seasonal and perennial acute conjunctivitis. Seasonal or perennial refers to the course of the disease, which is observed in both sexes and affects between 15% and 40% of the population. The seasonal form, also known as hay fever conjunctivitis, is an acute disease usually caused by an external allergen, such as pollen from grasses, and for this reason, it manifests only during specific periods of the year, which may vary depending on the seasons and climate.

Perennial conjunctivitis, on the other hand, is chronic, with periods of exacerbation and remission, and is usually caused by indoor air antigens, such as dust mites or pet dander. The difference between the two conditions lies in the periodicity of the symptoms. Seasonal allergic conjunctivitis typically occurs more frequently from spring through fall and subsides during the colder months, whereas perennial conjunctivitis occurs throughout the year and is generally milder. Both forms can be mild, moderate, or severe, depending on the intensity of the symptoms and their impact on the quality of life. However, more than half of patients report daily symptoms, and about 75% consider their symptoms severe.

Seasonal and perennial allergic conjunctivitis are the ocular forms of systemic allergic disease (type 1 hypersensitivity, IgE-mediated), which typically manifests as allergic rhinitis and/or asthma.

Allergic asthma, rhinitis, and conjunctivitis share a common pathophysiological mechanism, representing an IgE-mediated reaction to airborne antigens. In sensitized patients, allergen-specific IgE binds to the surface of mast cells, so when the antigen binds to it, the release of histamine and other preformed inflammatory mediators, such as leukotrienes, prostaglandins, and others, is triggered. This activates an inflammatory response and within 30 minutes an acute reaction is observed, followed by a second delayed phase associated with the accumulation of additional mast cells, eosinophils, and other inflammatory cells in the conjunctiva, which sustains the symptoms.

In this form of conjunctivitis, itching and chemosis (eye irritation) are key symptoms. It is characteristic that they are disproportionate to the degree of hyperemia. The itching is usually more pronounced in the nasal half of the conjunctiva, and the secretion is watery and sometimes mucinous (slimy). Corneal involvement is rare in seasonal and perennial conjunctivitis, although it may occur in more severe cases. Spring keratoconjunctivitis is a bilateral chronic inflammatory disease that is usually observed in areas with tropical or warm climates. According to literature data, in Europe, there are between 1.2 and 10.6 cases per 10,000 people. It affects school-age children, predominantly boys. It often develops seasonally, with peak frequency at the end of spring and the beginning of summer, suggesting a hypersensitivity reaction to pollen.

Is there a connection with other atopic diseases?

In 15 to 60% of affected children, other atopic diseases are also detected. Only 50% of them have sensitivity to aeroallergens. For this reason, it is believed that this disease has a complex etiology, including hypersensitivity to allergens, as well as sensitivity to various other environmental stimuli such as sunlight, wind, and dust. The microbiome of the ocular surface also plays a role in the disease’s etiology. The influence of genetic and endocrine factors is also noted in relation to the predisposition of males, family history of the disease, and racial differences in disease progression.

Spring keratoconjunctivitis is clinically classified as tarsal, limbal, or mixed. The tarsal form is more common in Europe and North and South America, while the limbal form is characteristic of African countries. In the tarsal form, giant papillae (>1 mm) appear in the tarsal conjunctiva, which may increase in size over time and resemble a cobblestone, surrounded by mucinous strands.

Spring keratoconjunctivitis can be complicated by corneal involvement in the form of punctate erosions, which usually affect the upper part of the cornea in more severe cases, and plaques and ulcers may form.

Symptoms include itching, redness, and tearing, sometimes with mucinous discharge as in all other forms of ocular allergy, but also photophobia and a foreign body sensation, without affecting the eyelid margin. Although spring keratoconjunctivitis has a relatively more severe course, the disease is self-limiting and tends to subside around the age of 20. It has a good prognosis, although up to 6% of patients develop complications that threaten vision. Atopic keratoconjunctivitis is the ocular manifestation of atopic dermatitis and is the most severe form of chronic allergic conjunctivitis. This is an inflammatory chronic keratoconjunctivitis that affects not only the ocular surface but also the eyelids.

Atopic keratoconjunctivitis is more common in men and can occur at any age, but it peaks in patients between the ages of 20 and 50. The percentage of patients with atopic dermatitis who develop atopic keratoconjunctivitis ranges from 25% to 42%.

Patients complain of severe itching for most of the year, which is usually more intense during the winter months. There is also discharge, which is more watery compared to vernal keratoconjunctivitis.

Atopic keratoconjunctivitis is a type 4 hypersensitivity immune reaction, predominantly involving Th1 cells, and it is considered to be at least partially IgE-dependent.

In contact blepharoconjunctivitis patients develop acute inflammation of the eyelid skin and conjunctiva, irritation, burning, itching, and watery discharge in relation to a product applied locally to the eyelids or conjunctiva. The reaction may develop several days after the first exposure to the allergen. This is a delayed type 4 hypersensitivity reaction initiated by an exogenous allergen and mediated by Th1 and Th2 lymphocytes, which secrete inflammatory cytokines. Giant papillary conjunctivitis is a chronic inflammatory disease characterized by giant papillae on the upper tarsal conjunctiva. There are controversies about including it as part of ocular allergic diseases since it is caused by chronic mechanical stimulation of the conjunctiva. Symptoms of giant papillary conjunctivitis include itching, foreign body sensation, watery or mucous discharge, mild conjunctival hyperemia, and the development of a papillary reaction on the upper tarsal conjunctiva.

What are the most common symptoms that can help us determine the type of conjunctivitis?

Allergic conjunctivitis usually affects both eyes as the most common symptoms are: itching, which is a distinctive sign of allergic ocular involvement, a foreign body sensation in the eye, and the presence of serous or mucous discharge.

Symptoms can be differentiated into those that appear predominantly in the early or late phase of the disease. Early signs are caused by the binding of histamine to its receptors and include tearing, itching, redness, and swelling. Late signs appear hours later and are characterized by epithelial infiltration with various cells: lymphocytes, neutrophils, basophils, and eosinophils.

This later phase leads to chronic inflammation, manifesting with photophobia, pain, decreased vision, and discharge. Each form of allergic conjunctivitis, in addition to common characteristics, has specific features in its clinical course that are important to recognize for proper diagnosis, prognosis, and adequate treatment.

Why is it important for patients to consult an eye specialist at the first symptoms? With what other serious eye disease can allergic conjunctivitis be confused?

Although allergic conjunctivitis generally does not lead to decreased vision, it manifests with numerous symptoms that significantly reduce the quality of life of affected patients. However, in some forms of the disease, vision impairment is possible, especially when the cornea is affected, as this can lead to the formation of corneal opacities, including vascular growth (pannus).

Such complications are more commonly observed in spring and atopic keratoconjunctivitis. In atopic keratoconjunctivitis, scarring of the palpebral conjunctiva and adhesions between the palpebral and bulbar conjunctiva may occur, leading to potential ocular complications. Therefore, it is important for these conditions to be diagnosed early and treated correctly to improve patients’ quality of life, reduce the number of relapses, and avoid potential complications.

Diseases of the ocular surface, such as dry eye syndrome, blepharitis, ocular rosacea, ocular toxicity from preservatives, or meibomian gland dysfunction, are included in the differential diagnosis of seasonal and perennial conjunctivitis.

What is the treatment? 

The treatment of allergic conjunctivitis is complex. Completely avoiding the allergen is the best option, but often difficult to achieve. Cold compresses, saline solution, and cold artificial tears or ointments are helpful because they relieve symptoms and dilute the allergen, especially in cases of acute allergic conjunctivitis.

The use of alpha-adrenergic agonists such as naphazoline, tetrahydrozoline, or brimonidine tartrate is applied in cases of hyperemia but is not recommended for adolescents and children. They act quickly and can be used for episodic itching and redness, but they have a short duration of action and many side effects, such as tachyphylaxis and local intolerance. They are rarely indicated and should be used sparingly and only as a short-term solution.

Among the local antihistamine medications, levocabastine, pheniramine maleate, and azelastine are most commonly used. Oral antihistamines like loratadine and desloratadine are very effective in cases of allergic rhinoconjunctivitis. However, they have more systemic side effects, such as sedation, compared to local antihistamines, and they also decrease tear production, which can have an adverse effect.

Mast cell stabilizers inhibit the degranulation of mast cells and are used for prevention, with a loading period of about 2 weeks before the expected effect.

Local dual-activity medications are clinically superior in terms of symptom relief and tolerance. They are considered first-line therapy and are the most frequently prescribed treatments. They block H1 receptors and inhibit mast cell degranulation. These include azelastine, alcaftadine, and ketotifen, which are approved for the treatment of itching, and olopatadine, which is approved for all signs and symptoms of ocular hypersensitivity. Olopatadine is safe, effective, and has been shown to be clinically superior to ketotifen.

Nonsteroidal anti-inflammatory drugs affect symptoms of allergic conjunctivitis, but patients report a burning/stinging sensation upon application, and therefore their use is not widespread.

Although corticosteroids are the most effective anti-inflammatory agents for allergic conjunctivitis, they should be administered by an ophthalmologist only in severe or very acute forms of conjunctivitis and in short courses due to frequent and severe ocular side effects.

The group of immunomodulators includes topical calcineurin inhibitors – cyclosporine A and tacrolimus. These medications are particularly effective in giant papillary conjunctivitis, vernal, and atopic keratoconjunctivitis to avoid steroid therapy and are useful when these conditions become steroid-dependent.

Another approach in the treatment of allergic conjunctivitis is immunotherapy, which aims to reduce the symptoms and signs of rhinitis and conjunctivitis caused by known allergens and to prevent their recurrence. Allergen-specific immunotherapy is considered when standard treatment fails or as a modifier of the natural course of the disease.

Biological preparations for systemic application such as omalizumab and dupilumab show good effects on some symptoms of allergic conjunctivitis in clinical trials but are not routinely used. In theory, biological treatment could lead to better outcomes because it blocks the main pathways of inflammation by binding to specific biological molecules, while other medications use non-specific ways to reduce conjunctival inflammation.

Two other new molecules, Insunakinra and Lifitegrast, which are inhibitors of interleukin-1 receptors, have shown effectiveness in treating allergic symptoms from the ocular surface.

Dr. Maria Benova is an ophthalmologist at the Specialized Eye Hospital “PENTAGRAM“. Her professional interests are in the field of diagnosis and treatment of anterior segment diseases glaucoma, cataract, as well as in the field of medical retina and oculoplastics. They possess diverse experience acquired in some of the largest hospitals in our country, including UMHAT ‘Aleksandrovska’, USBAL ‘Acad. Iv. Penchev’, UMHAT ‘Tsaritsa Yoanna – ISUL’, UMHATEM ‘N. I. Pirogov’.

Source: credoweb.bg