Allergic Conjunctivitis 101 – An Introduction To The Disease

As the name describes, allergic conjunctivitis is a disease the affects the conjunctiva of eye and results due to an allergic reaction. Knowing this condition better will help you understand the basic mechanism behind it and take measures against its occurrence.

allergic conjunctivitis

Exposure to the fur of a pet can cause allergic conjunctivitis in some people.

An Introduction To Allergic Conjunctivitis

‘Conjuctiva’ is a thin, transparent layer that covers the white portion of eye. Conjunctivitis is a term used to refer to the inflammation of the conjunctiva, a condition that occurs due to variety of reasons.

What Causes Allergic Conjunctivitis?

Allergic conjunctivitis is an excessive reaction of the body’s immunological defense system upon exposure to some allergens (allergy-provoking substances). It appears as an inflammation of the conjunctiva and is characterized by allergic conjunctivitis symptoms redness and itchiness in the eyes. Excessive tears, pain, and swollen eyelids may also appear as symptoms in some cases.

Allergic Conjunctivitis – Some  Common Allergens

  • Pollen grains shed by plants, grass, and weeds (they account for most cases of this disease)
  • Fur of animals/pets
  • Objects of regular use, such as perfumes, deodorants, cosmetics, and other makeup materials
  • Air pollution
  • Eye medicines/devices, for example, eye drops and contact lenses

The Mechanism That Triggers Allergic Conjunctivitis 

The basic mechanism that causes the allergic response of the eye is the sensitization of the conjunctiva to a particular substance (allergen). So whenever the conjunctiva is exposed to such an allergen, sensitization sets in to trigger an allergen-specific response, usually during subsequent exposures to such allergens.

Such an allergic reaction is associated with the release of chemicals like histamine, prostaglandins, interleukins, and allergy-specific antibodies (Immunoglobulin E or IgE).

The main cells involved in this cascade are ‘Mast cells’ and ‘T-helper cells’. Mast cells are components of the human body’s defense system and T-helper cells are a part of the white blood cells that protect the body from different foreign particles.

After exposure to allergens like pollen, T-helper cells release IgE antibodies that attach themselves to mast cells and activate them to release various chemical mediators like histamine and prostaglandins.

Histamine is responsible for the dilatation (widening) of the blood vessels of the conjunctiva. Excessively dilated blood vessels in the conjunctiva give it a “reddened look”.

As inflammation sets in, the conjunctiva becomes red and itchy. Excessive watering from the eyes and eye pain may supervene.

When Does Allergic Conjunctivitis Occur?

The symptoms of allergic conjunctivitis normally occur during seasons like summer and early spring, due to the high presence of pollen in the air during these times of the year.

Are You Prone To This Condition?

If you are prone to regular allergies, you might also be prone to allergic conjunctivitis. People with allergic diseases like asthma, hay fever, eczema, urticaria, and allergic dermatitis are also susceptible to allergic conjunctivitis.

Is Allergic Conjunctivitis Contagious?

Allergic conjunctivitis is not a communicable disease. Though other types of conjunctivitis may spread from one person to another, allergic conjunctivitis is restricted only to people with allergic hyper-responsiveness.

Types Of Allergic Conjunctivitis

  • Seasonal Allergic Conjunctivitis

    It is the commonest form of ocular (eye) allergy. Seasons like early spring and summer are associated with the shedding of pollen from trees, weeds, and grass. An allergic response to these particles leads to a condition called ‘hay fever’. Additional symptoms like a runny nose, sore throat or sneezing may be seen. Seasonal allergic conjunctivitis may repeat every year at these particular times. Symptoms typically last for few weeks after the exposure.

  • Giant Papillary Conjunctivitis

    It is a rare form of allergic conjunctivitis seen in contact lens users, usually due to poor maintenance of contact lenses. Allergy to the contact lens material or the debris retained behind contact lenses provokes this response.

  • Vernal And Atopic Conjunctivitis

    Vernal conjunctivitis is seen in children residing in warm climates and atopic conjunctivitis occurs in males between 30 and 50 years of age.

  • Phlyctenular Conjunctivitis

    It occurs as an allergic reaction to certain microorganisms (mainly TB bacilli, Chlamydia, etc.)

The Complications Of Allergic Conjunctivitis

Complications are rare with allergic conjunctivitis, but in cases where the condition is ignored or untreated, an infection may develop, especially if appropriate hygienic measures are not taken.

While it’s not a fatal disease, allergic conjunctivitis can nevertheless cause serious problems for the eye if not countered on time through allergic conjunctivitis treatment measures.

Allergic Conjunctivitis Symptoms – How To Identify The Problem

Allergic conjunctivitis is caused due to the body’s overreaction to allergens (substances that provoke allergies) like pollen, perfumes, and animal fur. Different eye diseases often present similar symptoms, however, certain distinctive allergic conjunctivitis symptoms make it easy to distinguish this condition from other types of conjunctivitis and eye diseases.

allergic conjunctivitis symptoms

Red, itchy, and painful eyes are key allergic conjunctivitis symptoms.

Allergic Conjunctivitis Symptoms – An Overview

Some of the most common allergic conjunctivitis symptoms include:

  • Redness In The Eyes

    The eye’s allergic response is associated with the release of chemical transmitters like histamine, prostaglandins, and interleukins. These substances cause the widening of the small blood vessels of the conjunctiva, and this process, known as vasodilation, makes the eyes appear red.

  • Itchy Eyes

    Intense itching in the eyes is the most common of all allergic conjunctivitis symptoms. It is seen in more than 75% of the cases of allergic conjunctivitis. Itching worsens when the eyes are rubbed. Histamine released from the mast cells (cells that provoke the allergic response of the eyes) irritates the nerve endings and causes an itching sensation in the eyes.

  • Foreign Body Sensation

    The patient is likely to experience a constant feel of something stuck within the eye. Itchiness and swollen eyelids may cause this type of feeling.

  • Painful Eyes

    The patient might experience a sharp pain in his eyes. 

  • Excessive Watering Of The Eyes (Lacrymation)

    The itchiness and inflammation trigger reflex tearing over time, causing the eyes to water.

  • Photophobia (Intolerance To Light)

    As the symptoms worsen, the patient will lose the ability to tolerate bright lights.

  • Trouble With Routine Activities

    Photophobia will make it difficult for the patient to carry out regular activities like driving, writing, reading, and working. 

  • Swollen Eyelids

    The inflamed lids may appear thick and swollen.

  • Nodule/Papillae Over The Eyelids

    These do not appear in every case of allergic conjunctivitis. Nodules are small lumps seen with the phlyctenular type of allergic conjunctivitis.

    Papillae are small, soft, and flat swellings along the insides of the eyelids, and are often seen in the giant papillary type of conjunctivitis.

When Do Allergic Conjunctivitis Symptoms Occur?

Unlike other types of conjunctivitis, allergic conjunctivitis has characteristic triggers for the onset of its symptoms:

  • Seasonal Variation – Allergic conjunctivitis symptoms often occur during seasons like summer or early spring, when the pollen from trees, weeds, and grass are shed into the air. Exposure to such allergens may precipitate the symptoms of allergic conjunctivitis.
  • Exposure To Allergens – Exposure to substances like pollen, animal hair, fur, bird feathers, perfumes, and cosmetics can also trigger this condition.
  • Climate - A warm and dry climate worsens allergic conjunctivitis and aggravates its symptoms. But cool and moist weather conditions are soothing and comfortable for patients.

What Causes Allergic Conjunctivitis Symptoms?

When the conjunctiva is exposed to allergens such as pollen, the mast cells and T-helper cells in the body are activated. These cells release histamine, prostaglandins, and other chemical transmitters. Histamine causes vasodilation i.e. the widening of the blood vessels. It also irritates the nerve endings within the conjunctiva. The overall cascade manifests externally in the form of allergic conjunctivitis symptoms.

Identifying The Main Allergic Conjunctivitis Symptoms

Allergic conjunctivitis presents symptoms that often resemble other types of conjunctivitis and other eye diseases. But it does have certain distinguishing features:

  • Seasonal onset and worsening of symptoms during warm and dry weather
  • Repeated occurrence of the condition, specifically during summer and early spring every year
  • Worsening of symptoms with increased exposure to specific substances like animal hair, feathers, pollen, etc.
  • Association with other conditions like Hay fever, a runny nose, sneezing, and asthma

Laboratory Findings That Point To Allergic Conjunctivitis

  • Eosinophilia

    Eosinophils are components of white blood cells, and they are specifically meant to tackle allergic diseases in the body. Most allergic conditions are characterized by an increased count of eosinophils (Eosinophilia) in the blood during the symptomatic phase. In allergic conjunctivitis, the eosinophil count in the blood is usually found to be higher than normal.

  • Skin Test

    Skin test is a test conducted to evaluate a person’s response to certain allergens. If he/she is allergic to that substance, the skin test appears positive. So, if you have allergic conjunctivitis or any other associated allergic disease like asthma, you are likely to test positive on the skin test.

  • Excess IgE

    Immunoglobulin-E (IgE) is an antibody produced in the body in response to allergen exposure. IgE levels are normally found to be high in the blood of patients with allergic conjunctivitis.

Allergic conjunctivitis is not a not a fatal disease, but it’s still dangerous and could cause serious trouble to your eyes. If you experience some of the allergic conjunctivitis symptoms detailed above, consult your doctor immediately to start allergic conjunctivitis treatment.

Allergic Conjunctivitis Treatment – Measures That You Can Take

Allergic conjunctivitis treatment depends upon the severity of the symptoms in the patient. This is mainly because mild allergic conjunctivitis symptoms may not require much treatment except for the use of cold compresses, while severe symptoms like ocular pain, intense itching, watering, and redness of the eyes need treatment with various medicines.

allergic conjunctivitis treatment

Staying away from allergens like pollen is recommended as part of allergic conjunctivitis treatment.

Allergic Conjunctivitis Treatment – A Look At What’s Involved

Allergic Conjunctivitis Treatment For The Root Cause

An allergy specialist will help you identify the substance that is inducing allergic conjunctivitis. Avoiding exposure to such allergens will automatically reduce the chances of the worsening and recurrence of this condition.

Treating The Symptoms Of Allergic Conjunctivitis

The most commonly preferred mode of allergic conjunctivitis treatment is topical (local or ocular) medication. As the symptoms arise mainly due to the activation of mast cells and the release of histamine, treatment is based on the use of eye drops or eye ointments that contain anti-histaminic and anti-inflammatory properties. Mast cell stabilizer drugs or steroids are also used for treating this condition.

  • Anti-Histaminics

    Allergic conjunctivitis symptoms arise due to the histamine released from the mast cells. Histamine causes redness, itching, and watering of the eyes. Anti-histaminic drugs (like Ketotifen, Cetirizine, Chlorpheniramine) destroy this substance and relieve the symptoms.

  • Mast Cell Stabilizers

    Mast cells are the main cells that initiate the chemical cascade for allergic reactions in the conjunctiva by secreting various chemical transmitters like histamine and interleukins. Exposure to the allergens generally activates the mast cells, and when the mast cells are stabilized, the cascade stops at that particular level and no further symptoms occur.

    Commonly used mast cell stabilizing eye drops contain drugs like Lodoxamide, Sodium Chromoglicate, and Nedocromil. They act by blocking the calcium-mediated gateways that cause the release of histamine from the cells. Mast cell stabilizers take quite a long time to act, but they are well known for their long-lasting action.

  • Dual Action Drugs

    Some drugs have both mast cell stabilizing and antihistaminic effects, and work by performing a dual action. Ketotifen and Olopatadine are examples of this type.

  • Steroids

    Steroids are hormones secreted by the adrenal gland of the body. They work by suppressing the immunological cells and decreasing the production of antibodies. Examples of steroids include Dexamethasone and Fluorometholone.

Essential Information About Steroid Use

Before using steroids, you should know what you’re getting into. Here are some basic facts that you need to know.

  • Steroids must be used cautiously and under a doctor’s observation only.
  • They must be used only in cases of severe allergic conjunctivitis and not for early and mild symptoms of the condition.
  • As the side effects of using steroids may outweigh their curative effects, they must be used with utmost caution.
  • Steroids suppress defensive cells in the body and favor the growth of organisms that cause infections. When used improperly, they may cause severe bacterial growth that affects the eyes, and this might permanently affect your vision.

Allergic Conjunctivitis Treatment – Dealing With The Other Types

  • Giant Papillary Conjunctivitis – Usually seen in contact lens users, this condition can be treated by discontinuing the use of lenses till the symptoms disappear.
  • Contact Conjunctivitis - As this condition is caused by contact with cosmetics and perfumes, it can be treated by avoiding exposure to such allergens.

Desensitization Allergen Immunotherapy

This is a method that involves the gradual desensitization of a person to allergens. The treatment follows the belief that administering allergens below the skin at certain intervals over a period of time can reduce the intensity of the allergic reaction.

This must be carried out only under medical supervision. Not all cases require this kind of treatment, but it is particularly helpful for atopic individuals.

Measures To Prevent Allergic Conjunctivitis

Prevention is always better than cure, so apart from allergic conjunctivitis treatment options, here are tips on preventing the condition. To prevent it, ensure that further exposure to the allergens does not occur, especially if you have had allergic conjunctivitis in the past.

  • Avoid the use of eye make-up materials
  • Do not use ocular (eye) medicines without medical advice. You may be allergic to some of them.
  • Never share your contact lenses with others.
  • Avoid rubbing the eye even if it itches intensely during conjunctivitis.
  • Wash your clothes, linens, and napkins properly so that no allergens are released.
  • Observe if your symptoms aggravate on exposure to your pet, as its hair or fur may be inducing or increasing your allergy.
  • Learn and adapt proper hygienic methods for handling contact lenses.

Never try to follow allergic conjunctivitis treatment measures of your own, no matter how mild it seems. Consulting an eye specialist at the first sign of this condition is highly recommended, in order to prevent the infection from turning severe.