Conjunctivitis is “pinkeye” – an inflammation of the lining of the eye. The conjunctiva is the clear membrane that lines the outside of the eye. Conjunctivitis usually affects both eyes but it can be only one sided because of the asymmetric way the lymph vessels supply the eyes.
The usual causes of conjunctivitis are bacteria, virus, allergy and chemical. Allergic and viral causes of conjunctivitis are most common.
Symptoms that may arise
Symptoms of allergic conjunctivitis include:
- Itching (always)
- Redness (always). The small blood vessels in the conjunctiva dilate.
- Discharge (usually)
- Clear, may be light yellow of green. Usually thin.
- Crusting (rare). The nasolacrimal duct drains tears and eye secretions. It clogs here, preventing drainage of the increased secretions. At night it accumulates and dehydrates making a clear or light yellow sticky material.
- Swelling (often). The conjunctive itself becomes edematous. Occasionally the upper eyelid swells from inflammation of the upper conjunctiva and rubbing.
- Runny nose (often)
- Clear nasal discharge from allergic rhinitis often accompanies allergic conjunctivitis
The allergic response which occurs with an inherited allergy creates a reaction on cell membranes, when exposed to certain proteins. These protein molecules are allergens that, when inhaled or make direct contact to the eye from the environment, start the process. When the allergen interacts with a receptor it produces changes in the cell membrane.
Mast cells are then stimulated to release histamine, cytokines and other substances that stimulate inflammatory responses in tissue. The result is red, itchy, weepy eyes.
Allergic versus Infective Conjunctivitis
Especially in the early stages of development allergic, viral or bacterial conjunctivitis can appear similar. Discrimination between the two is important for appropriate treatment and potential isolation requirements for infective conjunctivitis.
Subtle differences can be perceived in symptom presentation.
- Pain: Infective conjunctivitis is more likely to have pain with increased itching and irritation. Severe allergic conjunctivitis can mimic infective closely.
- Photophobia: The bright light can be annoying in allergic but severe photophobia is usually indicative of infective conjunctivitis.
- Discharge: Drainage tends to be more copious, thicker and more yellow or dark greenish in infective conjunctivitis.
- Injection: The redness appears more “angry” in infective conjunctivitis.
- Infective Conjunctivitis occurs randomly compared to the recurrent nature of allergic.
Types of Allergic Conjunctivitis
- Seasonal (SAC) and Perennial Allergic Conjunctivitis (PAC) are both mast cell mediated. The only difference is in the timing associated with recurrent symptoms.
- Vernal Keratoconjunctivitis (VKC) and Atopic Keratoconjunctivitis (AKC) are both associated with the more cytotoxic cells released. Both are usually seen in males. The only difference is in the age of presentation. VKC occurs in childhood while AKV is usually between the ages of 30-50.
Any protein can potentially be an allergen to any given individual genetic makeup. Common inhalant allergies are to ragweed, animal dander’s, pollen, and molds.
Treatment of the problem
Treatment is supportive and topical to interrupt the allergic reaction.
- Wash hands before and after eye contact. The local inflammatory changes make the tissues more open to infection with pathogens in the environment. Limit potential auto-inoculation by washing hands and keeping hand sanitizer close by.
- Avoid rubbing.
- Apply a cool damp compress for comfort. Dab eyes without rubbing to remove discharge.
- Short term use of a nasal decongestant can improve ocular symptoms.
- Warm compress to the inside corners of the eye by the nose can help open blocked nasolacrimal ducts.
Prescription and over the counter (OTC) eye medications will contain one or a combination of antihistamine, mast cell stabilizer or steroid compounds.
Mast cell stabilizers take a longer time to become effective than antihistamines but have fewer side effects. While this is more pronounced when taken orally it also applies to topical administration. Examples of mast cell stabilizers are Alomide (Lodoxamide) by prescription and Alocril (nedocromil).
Steroid preparations for ophthalmic use are usually reserved for severe or chronic eye conditions. Decadron (dexamethasone) and Durezol (difluprednate) are two examples. Several steroid/antibiotic combinations exist.
Many herbs contain phytochemicals (phyto-plant) that are bioactive. They generally provide both antihistamine and anti-inflammatory actions. Several herbs are used as a cool infusion and dropped into the inflamed eye. The herbs can be used singly or in combination: Chamomile (Matricaria recutita), fennel seed (Foeniculum vulgare) and marigold (Calendula officinalis). Soaked plantain leaves as a compress can provide relief from itching.
For severe or chronic allergic conjunctivitis treating allergies systemically may be required. In addition to the same classes of medications commonly recommended for topical use e.g. antihistamine, mast cell stabilizers and steroids, there are two other types of oral medications. Drugs that interrupt the allergic events early on can include Leukotriene inhibitors. Drugs such as Singulair prevent mast cell release of histamine. Decongestants can improve ocular symptoms by vasoconstriction.
If the allergic condition is severe or chronic effects are developing allergy desensitization is available. This is usually a series of injections that are designed to modulate the body’s response to a specific allergen. Over time the body reacts milder and may stop allergic symptoms completely to that specific allergen.
Summary – A Common Condition
Seventy per cent of people with allergic conjunctivitis seek treatment. Treatment of infective conjunctivitis may require antibiotic or other therapeutic measures. Long term damage can occur from chronic allergic conjunctivitis.
Good treatments are available. If symptoms persist or change reevaluate with your health care provider.