Eye allergy, also known as ocular allergy or allergic conjunctivitis, occurs when something you are allergic to causes irritation to the conjunctiva. The conjunctiva is a fragile membrane that makes up the outer surface of the eye and inside of the eyelid. When the eye is exposed to an allergen, it elicits a reaction and causes symptoms such as itching, redness, tearing, or swelling.
Allergic conjunctivitis is most commonly caused by seasonal allergens, which include pollen and mold spores. With seasonal allergens, symptoms tend to worsen while outdoors and on days where pollen counts are found to be high. Perennial or indoor allergens, such as pet dander and dust mite, also contribute to allergy symptoms. These types of allergens are experienced year-round and can be exacerbated around pets or while cleaning the house. Air pollution is another contributing factor, as the various chemical components present in pollution can irritate mucous membranes and increase the occurrence of allergic symptoms.
The tear film is the first line of defense for the eye, protecting the eye from allergens as a barrier, washing away allergens, and diluting allergens and inflammatory substances released by immune cells on the eye. However, with the increased visual tasking such as computer and handheld device use, more people have compromised tear films and ocular surfaces. This trend, combined with increasing issues of pollution and decreased air quality, contributes to rising rates of allergy and impact of allergies.
Most allergy symptoms, while bothersome, pose minimal threat to eyesight. However, some individuals can develop an allergic condition known as atopic keratoconjunctivitis (AKC). AKC has been identified in about <1-8% of the adult population and is not commonly diagnosed. Patients with AKC have an increased number of immune cells at the surface of the eye, causing them to exhibit a hyper immune response to allergens. AKC symptoms of eye redness, itching and tearing can often resemble seasonal and perennial allergic conjunctivitis, but AKC is more progressive and severe. It has more of an inflammatory component, with toxic substances released from immune cells on the eye that create tissue damage. It also involves the cornea (clear front surface of the eye), which becomes more susceptible to damage, as well as the eyelids, which can become red and very itchy, and ultimately manifest other signs of atopic dermatitis allergy. AKC’s type of heightened response causes deterioration to the eye’s surface and can eventually lead to vision loss, if not treated appropriately. This condition should be monitored by an eye doctor to keep under control.