Types of Eye Allergies and Their Symptoms

For those of us with allergies, eye allergies can be especially troublesome. Not only can eye allergies drive us crazy, but they can also be debilitating to some. In some people, ocular allergies can be a real threat to vision. Allergies tend to involve the eye frequently because just like the nose, the eye contains mucous membranes that can be exposed to the atmosphere and to potential allergy triggers.

Types of Eye Allergies

When we think of eye allergies we tend to think of itchy, irritated eyes. However, depending on the type of allergies, other symptoms can also be present. In medical terms, most eye allergies are referred to as "allergic conjunctivitis." The conjunctiva is the clear membrane that covers the eye and lines the inner eyelids. There are four basic types of allergic conjunctivitis and each has slightly different symptoms.

Perennial and Seasonal Allergic Conjunctivitis

Perennial and seasonal allergies is the most common type of eye allergy. Seasonal allergies (SAC) occur during certain times of the year when there are high levels of pollen or mold in the air. Perennial allergic conjunctivitis (PAC) tends to occur year-round and has milder symptoms.

People who suffer from these types of allergies are easy to spot as they are rubbing their eyes vigorously and their eyes appear swollen. Doctors recognize these patients because they tend to have dark areas under their eyes, referred to as allergic shiners.

What affects the eyes often affects the nose, so people who suffer from these types of allergies also tend to have a runny nose, nasal congestion, and may sneeze a lot. These types of allergies are usually caused by mold, dust mites, pet dander, or other allergens found around the house. People with these type of allergies complain of itching, swollen eyelids, redness, stringy, white or clear watery discharge, and burning.

Vernal Keratoconjunctivitis

Vernal keratoconjunctivitis (VKC) can be triggered by pollens, dust mites, mold, and animal dander. It can affect the cornea, the clear dome-like structure spanning the front of the eye, as well as the mucous membranes in the conjunctiva.

VKC most often affects males and usually develops before age 10. It's most common in subtropical, dry climates. People who have vernal keratoconjunctivitis also tend to have asthma and skin conditions, such as eczema.

Symptoms may include severe itching, tearing, ropy, white discharge, ptosis (a condition where the upper eyelid may hang down lower than normal), cobblestone bumps under the eyelid called papillae, and light sensitivity.

VKC can also cause a unique reaction called Horner-Trantas Dots, which are small bumps of inflammatory cells around the limbus, the tissue located at the edge of the cornea. As mentioned before, VKC can also affect the cornea. One very important concern for people with VKC is the development of shield ulcers on the cornea. The body develops shield ulcers in reaction to the cobblestone bumps under the eyelid and from the over-reacting immune system. VKC can put an individual at risk of losing vision if not treated properly.

Atopic Keratoconjunctivitis

Atopic keratoconjunctivitis (AKC) is a severe form of eye allergy that can involve the cornea of the eye as well as the inner lining of the lower eyelids. AKC usually affects young adults, starting in the late teens to the early twenties, and can persist for decades. The majority of people with AKC also have atopic dermatitis, allergic rhinitis, and/or asthma. Severe AKC can lead to complications including cataracts, eye infections, and blindness.

Symptoms of AKC can include severe itching, light sensitivity, thicker, stringy discharge, skin reactions around the eyes, and large papillae (bumps under eyelids). AKC can also affect the cornea. People with AKC may develop new blood vessels in the cornea. Also, small collections of white blood cells may develop in the cornea. There is also a relationship between AKC and a condition called keratoconus. Keratoconus is a condition in which the cornea becomes extremely steep and may eventually cause very distorted vision. The cornea also becomes very thin, causing significant changes in vision, scarring, and distortion of the cornea.

Although keratoconus is thought to be inherited, some believe that keratoconus is actually caused by the intense "rubbing of the eye" associated with severe forms of eye allergies.

Giant Papillary Conjunctivitis

Giant papillary conjunctivitis (GPC) is mostly associated with wearing contact lenses. It is thought to be an allergy-related to proteins that are often present in our tears. Normally, they may not be a problem. However, when contact lenses are frequently worn, these proteins can bind to the surface of the contact lenses.

When chronically exposed to this protein, symptoms that are very similar to allergies begin to appear. Very large papillae begin to form on the underside of the upper eyelid. These papillae act like little fingers and begin to grab or stick to the contact lens, causing the lenses to move much more than normal.

One method optometrists use to reduce the change of GPC is to fit patients into daily, disposable contact lenses that can be worn for one day and then thrown away. They receive a fresh, brand-new lens every day.

Symptoms of GPC include itching, mucus discharge, blurred vision, uncomfortable or moving contact lenses, and foreign body sensation.

Diagnosis

Primary care and allergy doctors are well versed in diagnosing and treating allergies. However, when allergic eye symptoms begin to become more severe, it is usually a good idea to involve an optometrist or ophthalmologist. Eye doctors have better medications in their allergy arsenal and are better equipped for dealing with allergic conjunctivitis. Also, they have special instrumentation and education that allow them to inspect the eye in order to rule out severe complications that can sometimes affect the eye and threaten vision.

Treatment

Treatment of eye allergies is multi-faceted. The first and most important part of an eye allergy treatment plan is to remove the trigger causing the allergies. The trigger is an antigen that your body has become allergic to.

Try staying indoors when pollen is at a peak for the area in which you live. Also, avoid going outdoors during certain times of the day when pollen counts may be higher, such as early morning and early evening. To reduce potential exposure while indoors, keep windows closed and use a good filter on your air conditioner.

To reduce allergy triggers that may be indoors, try to lower your exposure to dust mites in your bedroom. Wash bedding frequently in hot water and run it through the dryer on a high heat setting.

Consider purchasing special covers for your pillows that keep mites away. Take a shower before going to bed to wash off pollen and other antigens that may collect on your skin or hair during the day or if you've been outdoors for an extended period.

When eye allergies become more significant, eye drops or oral medications may be an option. One common recommendation made by eye doctors before prescribing prescription medications is to instruct the allergy-sufferer to instill chilled, over-the-counter, artificial tears several times a day.

This serves to rehydrate and lubricate your eye and dilutes the numbers of antigens present in your tears. A cold artificial tear is like applying a cold compress to your eye but it goes directly into your eye. This constricts blood vessels and feels great on an irritable, itchy eye.

When eye allergies become more severe, prescription eye drops and oral medications may be indicated. High-quality prescription antihistamine eye drops are available that control allergies often with just one drop per day. 

Depending on how miserable a patient is feeling or how much inflammation is present from the allergies in the eyes, eye doctors will sometimes prescribe corticosteroid eye drops. While these drops quell the inflammation quickly, they must be used very carefully and you must be monitored by an eye doctor.

Long term corticosteroid use can cause glaucoma and cataracts in some patients. Oral antihistamines are also sometimes prescribed and are available over-the-counter and by prescription. In more severe allergies and in people who may also suffer from asthma, leukotriene modifiers are prescribed. These are drugs that block leukotriene chemicals. Leukotrienes are chemicals released by our body when we come into contact with an allergy trigger.

Allergy shots (immunotherapy) can be a very effective treatment for allergic eye diseases, including allergic conjunctivitis, AKC and VKC.