It is estimated that the prevalence of ocular allergies is as high as 30% in the U.S. Sometimes called allergic conjunctivitis, ocular allergy occurs when something you are allergic to irritates the conjunctiva (the surface covering of the eye). Ocular allergies can be seasonal – episodic, related to pollen and leaf molds; or environmental – year-round, related to dust, mold, pet dander. Establishing the triggers for these allergies allows planning to reduce symptoms.
Mechanism of Ocular Allergy
An allergen is a substance that stimulates an allergic response. Allergic conjunctivitis starts when the immune system identifies an otherwise harmless substance as an allergen. This causes your immune system to overreact and produce antibodies called Immunoglobulin E (IgE). These antibodies travel to cells (Mast Cells) that release histamine and other chemicals which cause an allergic reaction. In this case, allergic reactions include eyes that water, itch, hurt or become red or swollen.
Symptoms of Ocular Allergy
Typical symptoms include:
- Watery eyes
- Sensitivity to light
- Eyelid swelling
Diagnosing Ocular Allergy
External Eye Examination – Examination of the ocular surface with a slit-lamp may reveal signs of allergy
Tear IgE Test – Currently not practical. In the future, it may be possible to detect the immunoglobulin (IgE) responsible for the allergic cascade.
Conjunctival Scraping – Staining cells removed from the conjunctiva can show white blood cells (eosinophils and mast cells) which are present in the allergic response.
Skin Scratch Test – Specific allergens are applied to the skin with a special applicator that lightly scratches the skin. This can identify the patient’s allergy triggers (allergens).
Ocular Allergy Skin Test
The knowledge obtained from the skin scratch test results can help physicians identify the offending allergens and aid in developing a customized treatment protocol.
The skin test is a simple, non-invasive procedure that superficially scratches the skin applying allergens to the exposed skin of the upper arm and forearm on each side. The device applies small amounts of the 58 most common allergens in our area along with both a positive and negative control. If you are allergic to an allergen, a small, itchy bump will appear within 20 minutes.
- Tests 58 allergens specific to our region of the country
- FDA-approved, in-office test
- No needles
- Results in 20 minutes
- Objectively identifies the root cause for ocular allergy
- Covered by Medicare and other insurers (may require pre-authorization)
Everyone is unique in their specific allergic triggers, knowing what you are allergic to is important for the effective treatment of allergies.
Treating Ocular Allergy
The mainstay of allergy treatment is avoidance of inciting allergens. About 75% of patients can reduce their symptoms with avoidance alone. Skin testing can identify a patient’s seasonal and environmental allergens permitting avoidance when possible.
Certain over-the-counter and prescription medicines may help reduce environmental allergy symptoms.
Antihistamines come in pill, liquid, nasal spray and eye drop form. They can relieve symptoms by blocking the effect of Histamine. They can reduce itching, tearing, sneezing and a runny nose.
Decongestants are available as pills, liquids, nasal sprays or drops. They help shrink the lining of the nasal passages and relieve nasal stuffiness. Use decongestant nose drops and sprays only for a short time.
Mast Cell Stabilizers. Cromolyn sodium is an eye drop or nasal spray that blocks the release of chemicals that cause allergy symptoms, including histamine and leukotrienes. This medicine has few side effects, but you must take it four times a day.
Corticosteroids are available as eye drops and nasal sprays. They reduce inflammation in the eye and nose and block allergic reactions. They are the most effective medicine type for allergic rhinitis because they can reduce all symptoms, including nasal congestion. Nasal corticosteroids have few side effects. However, long-term use in the eye or nose can increase cataract and increase the pressure in the eye.
Leukotriene Receptor Antagonists block the action of important chemical messengers (other than histamine) that are involved in allergic reactions. These are used for allergic asthma.
Many people with allergies do not get complete relief from medications. This means they may be candidates for immunotherapy. Immunotherapy is a long-term treatment administered by an Allergist that can help prevent or reduce the severity of allergic reactions. It can change the course of allergic disease by modifying the body’s immune response to allergens.
Subcutaneous Immunotherapy (SCIT). Allergy Shots have been around for more than 100 years and can provide long-lasting symptom relief. SCIT is a series of shots that have progressively larger amounts of allergen. An injection of the allergen goes into the fat under the skin. Over time, allergic symptoms generally improve. Many patients experience complete relief within one to three years of starting SCIT. Many people experience benefits for at least several years after the shots stop.
Sublingual Immunotherapy involves placing a tablet containing the allergen under the tongue for 1 to 2 minutes and then swallowing it. In 2014, the FDA approved three types of under-the-tongue tablets to treat grass and ragweed allergies. More are in development. You take SLIT tablets daily before and during grass or ragweed season. This treatment offers people with these allergies a potential alternative to allergy shots.