Allergic Conjunctivitis

Allergic conjunctivitis is a type of conjunctivitis caused by allergens such as pollen or house dust.
There are various symptoms, including eye redness, eye discharge, and itchy eyes.

In this article, we will cover the following topics:

・Types and symptoms of Allergic Conjunctivitis
・How to treat Allergic Conjunctivitis
・How to prevent and treat Allergic Conjunctivitis

Allergic conjunctivitis refers to conjunctivitis caused by allergens such as pollen or house dust.
Allergies are the body’s overprotective response to a foreign substance that enters the body. Allergic conjunctivitis can occur at any age, but studies have shown that it is most common in people in their 40s, followed by teenagers.
*Source: Prevalence survey by the Japanese Society of Ophthalmic Allergies, 2017.

The prevalence of allergic conjunctival disease is 48.7%, which means that one out of every two people in Japan has some kind of conjunctival symptoms.

The conjunctiva is a translucent membrane that covers the surface of the white eye and the back of the eyelid. The conjunctiva is what allows the eyeball to move any direction without adhesion between the eyeball and eyelid. At the same time, the conjunctiva separates the outside from the inside of the eye and making it susceptible allergens, viruses, and bacteria.
Allergic conjunctivitis is an inflammation of the conjunctiva caused by allergens, and unlike infectious conjunctivitis caused by viruses or bacteria, it is not contagious from person to person.
*For information on conjunctivitis (infectious), please refer to this article.

Allergic conjunctivitis is caused by a variety of allergens, some seasonal allergens, such as pollen, and some perennial, such as house dust mites.
It’s a general term for allergic diseases of the eye, and the following subjective symptoms may occur.

・Inflammation of the conjunctiva
・Itchy conjunctiva
・Redness of the eye (Hyperaemia)
・Gritty sensation of the eye (foreign body sensation)
・Eye discharge
・Heavy tearing
・Bumps (papillae) on the back of the eyelids

Redness of the eye

The redness of the eye caused by conjunctivitis is due to the dilation of blood vessels on the surface, which causes the eye to appear red and bloodshot. When the conjunctiva is hyperemic, the surrounding area of the white eye becomes red.

Eye discharge

Tears contain a component called mucin. When mucin binds to the epithelium, cells in blood, and pathogens on the surface of the eye, it causes eye discharge.
If you see a lot of eye discharge/ mucus not only when you wake up but also during the day, you should pay attention. In allergic conjunctivitis, clear or white, jelly-like eye discharge may appear from both eyes for a month or more.

Foreign body sensation and gritty feeling in the eye

The sensation of a foreign body (grittiness sensation) is a symptom that occurs not only when a foreign body enters the eye, but also when the cornea or conjunctiva is inflamed.
Recently, dry eye symptoms caused by long-time contact lens wear or computer operation (VDT work) are also a common cause.

*Please click here to read the article on VDT syndrome, which has been increasing in recent years.

Itchy eyes

When the conjunctiva becomes inflamed, the eye feels itchy. Sometimes the whites of the eyes may swell into a blister-like appearance. If itching symptoms persist, it’s better to consult an ophthalmologist.

Allergic conjunctivitis can be classified into several types depending on the allergen and the symptoms.

Hay fever

Allergies caused by pollen lead to conjunctivitis. Cedar (spring), weeds from the grass family (summer), and ragweed (fall) are well-known examples, but in fact, pollen of all kinds is flying all year round except during the winter season.
In particular, pollen from trees such as cedar and cypress is known to be carried by the wind for distances of more than 100 kilometers.
Pollen allergy is caused by the body overreacting and releasing chemical messengers such as histamine. In addition to various symptoms that appear in the eyes, nasal symptoms such as sneezing, runny nose, and nasal congestion are often associated.

*Edited by our company based on the guidelines for nasal allergy treatment (Japanese Society of Otorhinolaryngology, Immunology and Allergy and Infectious Diseases).

House Dust

House dust refers to tiny particles of dirt that are barely visible to the naked eye, such as dust mites, mite corpses and excrement, human dandruff, hair, and mold mixed in with the dust.
Conjunctivitis occurs when airborne house dust particles adhere to the conjunctiva, just like pollen. The symptoms of conjunctivitis are similar to those of hay fever. However, unlike seasonal hay fever, conjunctivitis is a chronic condition that continues all year round. This is because house dust particles are always around us.
Therefore, it is important to remove antigens through environmental improvements such as cleaning, removing mites, and ventilation.

Vernal Keratoconjunctivitis

Vernal keratoconjunctivitis is a chronic, severe allergic conjunctivitis that occurs primarily in prepubertal boys, and is an inflammatory disease of the cornea and conjunctiva. It is now associated with atopic dermatitis and can cause severe symptoms even in people in their 20s.
The eyes become extremely itchy, and numerous small scratches appear on the surface of the cornea, causing intense itching, roughness, and sensitivity to light. In addition, a papilla shaped like a stone may appear on the upper eyelid, and a white cloudy layer may appear on the cornea. As the condition progresses, the epithelium of the cloudy area may peel off, leading to a corneal ulcer.

Giant papillary conjunctivitis

Giant papillary conjunctivitis is a condition in which numerous papillae develop and become inflamed behind the upper eyelid. An allergic reaction to proteins in dirty contact lenses can also cause this condition.
This condition is characterized by a foreign body sensation, blurred vision, eye discharge, and in severe cases, a tendency for the contact lens to slip upwards.

Atopic Keratoconjunctivitis

Conjunctivitis occurs in people with skin lesions on the face and eyelids caused by atopic dermatitis, causing chronic year-round itching and eye discharge.

Treatment and prevention of allergic conjunctivitis includes symptomatic treatment to suppress the allergy and treatment to prevent the allergic reaction.

Use eye drops

Two types of eye drops with anti-allergic effects are used: histamine H1 antagonist eye drops and mediator release inhibitor eye drops.
Histamine H1 antagonist eye drops directly block the action of histamine and are used when the itching is severe. On the other hand, mediator release inhibitor eye drops take about two weeks to have an effect of suppressing the increase of histamine, so they must be used before symptoms appear.
For people who suffer from hay fever at certain times of the year, using eye drops before you experience symptoms such as itching can not only prevent hay fever, but also reduce the symptoms when it does occur.
Eye drops that reduce the histamine receptors that cause itching are also effective as initial treatment. In severe cases, steroid eye drops may be used, but because they increase intraocular pressure, they must be used after an ophthalmologist measures intraocular pressure.

Take Anti-allergic medication

If eye drops alone do not improve symptoms, oral anti-allergy medication may be used. If the symptoms of vernal keratoconjunctivitis are severe, steroid or immunosuppressant eye drops may also be effective.

Allergen immunotherapy

Conventional hyposensitization or desensitization therapy is not a symptomatic treatment but a method to improve the allergy itself.
Sublingual immunotherapy preparations and subcutaneous injection preparations are used to prevent allergic reactions to dust mites and cedar pollen.

We will explain preventive measures to reduce the unpleasant symptoms of allergic conjunctivitis, such as itching and redness.

Blocking pollen

It is effective to reduce the opportunities for pollen to reach the cornea and nasal mucosa as much as possible. In addition to avoiding going outside on days and times when pollen is high, it is a good idea to wear goggle-type glasses and a pollen prevention mask when going outside.

Eliminate mould and dust mites

It is important to eliminate mold and dust mites that can cause allergies.

・Vacuum slowly and carefully.
・Wash and dry bedclothing often
・Use an air purifier

Keep the room temperature below 20°C and humidity below 50%, and improve ventilation to prevent the breeding of dust mites. Even in summer, keeping humidity below 70% will help prevent mold from growing.
In winter, condensation is likely to cause mold, so it’s a good idea to wipe down frequently and use insulation to prevent condensation.

Use eye drops and eye washes

To clean pollen and house dust that has gotten into the eyes, it’s important to use eye drops or eye washes that do not contain preservatives.
Rinsing with tap water washes away tears from the surface of the eye, which can result in damage to the cornea.

How long does it take for allergic conjunctivitis to heal?

In most cases, symptoms subside within one to two weeks with the use of anti-allergic eye drops and measures such as reducing contact with allergens. If symptoms persist, visit an ophthalmologist as other diseases may be complicating the condition.

Are you worried about spreading allergic conjunctivitis to others?

Allergic conjunctivitis is not contagious from person to person. It is caused by contact with allergic substances such as house dust or pollen, which is different from infectious conjunctivitis caused by viruses.

Can I wear contact lenses if I have allergic conjunctivitis?

If you have symptoms of conjunctivitis, it is safer not to wear contact lenses or to wear them for a short period of time.
When wearing contact lenses, proteins or pollen on the lenses can come into contact with your eyes, which can worsen conjunctivitis.
As conjunctivitis worsens, protein secretion to the ocular surface increases, making the contact lenses even more susceptible to contamination. This can lead to a vicious cycle of increased allergies.