Ocular Allergies - Causes, Symptoms, and Management

Introduction

The eyes are in constant contact with the environment and, hence, vulnerable to different irritants. Allergy is an immune response to a foreign substance. Ocular allergies, also called eye allergies, comprise various clinically different conditions that can be considered hypersensitivity disorders. These include acute allergic conjunctivitis, atopic conjunctivitis, seasonal hay fever (seasonal allergies), giant papillary conjunctivitis, vernal conjunctivitis, etc. Classifying these conditions can be challenging as they are complex, and their epidemiology is not adequately studied. Ocular allergies can be debilitating for patients and difficult for physicians to diagnose and treat. However, there are many ways to manage or prevent ocular allergies so they do not affect the individual’s routine activities.

What Are Ocular Allergies?

Ocular allergy or eye allergy is a hypersensitive response of the eyes when it comes in contact with any allergen or other irritating substances. It is a broad term that includes a group of allergic conditions causing inflammation of the conjunctiva (a clear membrane lining the eyelids and covering the white portion of the eyes) or its surrounding structures. It occurs due to the exposure of the ocular surface to a wide variety of allergens, making it highly susceptible to allergic reactions. The condition ranges in severity from mild to severe and has the potential to cause impairment of vision. One of the most common ocular allergies is allergic conjunctivitis (inflammation of the conjunctiva due to allergy).

What Are the Types of Ocular Allergies?

There are different clinical forms of ocular allergies, mainly divided into two main groups; the first group includes seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC). These are more frequent forms and are diagnosed by general practitioners or eye specialists. SAC is more prevalent during spring seasons or when the pollen levels are high, whereas PAC can present throughout the year as it is caused by dust, mold, animal dander (shed skin cells), etc. The second group includes atopic keratoconjunctivitis (AKC) (inflammation of the eyelids) and vernal keratoconjunctivitis (VKC) (recurrent bilateral conjunctivitis). These are less frequent, chronic, and severe forms of ocular allergy that must be carefully diagnosed and managed by expert ophthalmologists in association with allergic specialists. These may even lead to corneal damage by causing ulcers or scarring (marks on the skin) of ocular tissues. Contact lenses or ocular prosthesis-associated (artificial components) ocular allergies are called giant papillary conjunctivitis (GPC) (formation of bumps in the inner eyelids).

What Are the Causes of Ocular Allergies?

When the eyes contact the allergens, the immune system reacts and produces immunoglobulin (IgE) antibodies. The mast cells produce a chemical substance called histamine, resulting in the eyes becoming itchy, red, and swollen. Ocular allergies are not contagious and do not spread to other people.

• Some predisposing factors of ocular allergy are environmental allergens, hot or dry environments, and genetic predisposition to allergic reactions.

• Some outdoor allergens, such as weeds, grass, pollen, cigarette smoke, and exhaust fumes, and indoor allergens, such as dust, mold, and pet dander, can trigger ocular allergies. Symptoms may worsen in people with seasonal allergies, especially outdoors or during high pollen counts.

• Allergic reactions can also occur due to cosmetics, household detergents, perfume, and specific medications or preservatives.

• Sometimes, the eyes do not come in direct contact with the allergens but can react to irritants such as insect bites, stings, or certain food products.

What Are the Signs and Symptoms of Ocular Allergies?

Symptoms of ocular allergies can be very annoying and can cause temporary blindness. Some of the common symptoms of ocular allergies include:

• Itching.

• Redness.

• Watery eyes.

• Swollen eyelids.

• Sensitivity to light.

• A feeling of dirt or grit in the eyes.

• Burning sensation in the eyes.

• Blurred vision.

• Some associated symptoms include sneezing, coughing, headache, and runny nose.

How Are Ocular Allergies Diagnosed?

The symptoms of ocular allergies can be similar to other eye diseases; hence, making an accurate diagnosis is imperative. A physician or an ophthalmologist can diagnose ocular allergies by its symptoms, and medical and family history. A comprehensive eye examination is conducted to rule out eye infections. In some cases, blood or skin tests can be recommended to identify the specific allergen causing the reaction. In some severe cases, the doctor may scrape a sample of the conjunctival tissue to examine the ocular cells under a microscope.

How Are Ocular Allergies Managed?

According to the Centers for Disease Control and Prevention (CDC), ocular allergy symptoms mostly improve after avoiding exposure to allergens. Certain medications and eye drops also help in reducing the symptoms. Some of the treatment measures for ocular allergies include:

• Oral medications (antihistamines) such as Fexofenadine, Cetirizine, Loratadine, etc., or anti-allergy eye drops such as Ketotifen, Emedastine, Bepotastine, Azelastine, etc. These are available both over-the-counter (OTC) or with a prescription. Corticosteroid eye drops may be prescribed temporarily in some severe cases to reduce inflammation and immune response.

• A cold compress on the eyelids with a cotton cloth soaked in cold water to soothe the eyes.

• Artificial tears to help remove the allergens.

How Can Ocular Allergies Be Prevented?

The best way to prevent ocular allergies is by avoiding the exposure to allergens. However, it may be difficult to identify them specifically. Some of the preventive measures include:

• Staying indoors, especially during mid-morning and early evenings or windy environments.

• Using eye-protective glasses when outdoors.

• Rubbing of eyes must be avoided as it can worsen the condition.

• Vacuum cleaning the house, especially carpets, curtains, soft toys, and furnishings.

• Installing an air purifier.

• Using scent-free household products or cosmetics.

• Wash one’s hands thoroughly with soap and water after handling pets.

• Discuss the symptoms with an ophthalmologist or allergic specialist to determine the allergen or suitable treatment options to manage the condition.

Conclusion

Ocular allergy is a broad spectrum of eye disorders ranging from common inflammatory reactions seen in outpatient clinics to less common and potentially sight-threatening diseases. It is characterized by symptoms such as itching, redness, watery eyes, and swollen eyelids. It can be managed by oral medications and antihistamine eye drops, but it is always better to consult a doctor or an eye specialist as the symptoms mimic several eye disorders. An important factor in managing ocular allergies is to avoid or limit contact with the allergens. However, new therapeutic strategies are still required to manage the complex pathogenesis of severe forms of ocular allergies.