Eye allergies, called allergic conjunctivitis, are a common condition that occurs when the eyes react to something that irritates them (called an allergen). The eyes produce a substance called histamine to fight off the allergen. As a result, the eyelids and conjunctiva — the thin, filmy membrane that covers the inside of your eyelids and the white part of your eye (sclera) — become red, swollen and itchy, with tearing and burning. Unlike bacterial or viral conjunctivitis, allergic conjunctivitis is not spread from person to person.
People who suffer from eye allergies usually (though not always) have nasal allergies as well, with an itchy, stuffy nose and sneezing. It is usually a temporary (acute) condition associated with seasonal allergies. However, in other cases, eye allergies can develop from exposure to other environmental triggers, such as pet dander, dust, smoke, perfumes, or even foods. If the exposure is ongoing, the allergies can be more severe, with significant burning and itching and even sensitivity to light.
What are allergic eye conditions?
Allergic conjunctivitis, also called “allergic rhinoconjunctivitis,” is the most common allergic eye disorder. The condition is usually seasonal and is associated with hay fever. The main cause is pollens, although indoor allergens such as dust mites, molds, and dander from household pets such as cats and dogs may affect the eyes year-round. Typical complaints include itching, redness, tearing, burning, watery discharge, and eyelid swelling. To a large degree, the acute (initial) symptoms appear related to histamine release.
The treatments of choice are topical antihistamine drops such as olopatadine (Patanol), decongestants, and the newer mast-cell stabilizer medications. Topical steroids should be used only if prescribed by a doctor for severe reactions and on a short-term basis because of the potential for side effects. In general, oral antihistamines likeloratadine (Claritin) or cetirizine (Zyrtec) are the least effective option, but they are often used for treating allergic rhinitis together with allergic conjunctivitis.
Rubbing itchy eyes is a natural response. However, rubbing usually worsens the allergic reaction due to the physical impact on the mast cells, which causes them to release more mediators of the immune response. Translation: Do not rub your eyes!
Conjunctivitis with atopic dermatitis
Commonly called “atopic keratoconjunctivitis,” this condition is a notorious cause of severe eye changes, particularly in young adults. Atopic keratoconjunctivitis implies inflammation of both the conjunctiva and cornea. “Kerato” means pertaining to the cornea. This form of conjunctivitis usually affects males 3 times more frequently than females and may begin in late adolescence. It’s peak incidence is in males aged 30 to 50. It is more common in those who had atopic dermatitis in early childhood. The condition is characterized by intensely itchy, red areas that appear on the eyelids. A heavy discharge from the eyes can occur, and the skin of the eyelid may show scales and crusts. In severe cases, the eyes become sensitive to light, and the eyelids noticeably thicken. If managed poorly, there can be permanent scarring of the cornea due to chronic rubbing and scratching of the eyes. This scarring can cause visual changes.
The triggers for atopic keratoconjunctivitis appear to be similar to those of atopic dermatitis. A search for common food allergies, such as eggs, peanuts, milk, soy, wheat, or fish is important. Airborne allergens, particularly dust mites and pet dander, have been overlooked as a significant contributing factor and should be evaluated and controlled.
The hallmark of treatment for allergic conjunctivitis is the use of potent antihistamines (similar to those used in atopic dermatitis) to subdue the itching. Topical antihistamines, mast-cell stabilizers, and the short-term use of oral steroids are all beneficial for relief of the itching. Occasionally, an infection of the area (usually with staphylococcus, commonly referred to as “staph”) worsens the symptoms, and antibiotic treatment may help control the itching. Allergy shots are useful in selected cases.
Atopic keratoconjunctivitis can lead to cataract formation in up to 10% of cases. In rare cases, blindness can occur.
Vernal keratoconjunctivitis is an uncommon condition that tends to occur in preadolescent boys (3:1 male to female ratio) and is usually outgrown during the late teens or early adulthood. (Vernal is another term for “spring.”) Vernal keratoconjunctivitis usually appears in the late spring and particularly occurs in rural areas where dry, dusty, windy, and warm conditions prevail. The eyes become intensely itchy, sensitive to light, and the lids feel uncomfortable and droopy. The eyes produce a “stringy” discharge and, when examined, the surface under the upper eyelids appears “cobblestoned.” A closer examination of the eye reveals severe inflammation due to the vast number of mast cells and accumulated eosinophils (a type of white blood cell involved in the allergic response), producing so-called called “Trantas dots.”
Improper treatment of vernal keratoconjunctivitis can lead to permanent visual impairment. The most effective treatment appears to be a short-term course of low-dose topical steroids. Topical mast-cell stabilizers and topical antihistamines can also be beneficial. Wraparound sunglasses are helpful to protect the eyes against wind and dust.
Keratitis, or the inflammation of the cornea, in vernal and atopic keratoconjunctivitis is largely caused by a substance that is released from the eosinophils called major basic protein.
Giant papillary conjunctivitis (GPC)
This condition is named for its typical feature, large papillae, or bumps, on the conjunctiva under the upper eyelid. These bumps are likely the result of irritation from a foreign substance, such as contact lenses. Hard, soft, and rigid gas-permeable lenses are all associated with the condition. The reaction is possibly linked to the protein buildup on the contact lens surface. This condition is believed, in part, to be due to an allergic reaction to either the contact lens itself, protein deposits on the contact lens, or the preservative in the solution for the contact lenses. Redness and itching of the eye develop, along with a thick discharge.
Allergy to contact lenses is most common among wearers of hard contact lenses and is least common among those who use disposable lenses, especially the one-day or one-week types. Sleeping with the contact lenses on greatly increases the risk of developing GPC.
The most effective treatment is to stop wearing the contact lenses. Occasionally, changing the type of lens in addition to more frequent cleaning or using disposable daily wear lenses will prevent the condition from recurring.
The giant papillae on the conjunctiva, which are characteristic of GPC, however, may persist for months despite these measures. Eye medications, such as cromolyn (Opticrom) or lodoxamide (Alomide), often are used in this condition, sometimes for several months. Contact lenses should not be worn while these medications are being used.
Allergy means that the immune system overreacts to something to which it has become sensitive. Symptoms of increased immune activity include redness, wateriness and itching. These are part of the body’s defence mechanism to things it sees as foreign and harmful. Causes include the following:
Seasonal conjunctivitis due to pollens and moulds
Seasonal conjunctivitis occurs at the same time each year. Most cases are due to pollen and occur in the hay fever season. Symptoms tend to last a few weeks each year and may vary with the pollen count. This is a measure of the amount of pollen in the air each day which is often published in the press and in online weather forecasts. Grass pollens tend to cause symptoms in early summer, usually from April through to July in the UK. Tree pollens may cause symptoms as early as February or March or as late as September depending on when the tree species involved shed their pollen. Various other pollens and moulds may cause symptoms later in the summer. Other symptoms of hay fever may also occur at the same time, such as a runny nose and sore throat.
This is a conjunctivitis that persists throughout the year (perennial means through the year). This is most commonly due to an allergy to house dust mite. House dust mite is a tiny insect-like creature that lives in every home. It mainly lives in bedrooms and mattresses, as part of the dust. People with perennial conjunctivitis usually also have perennial allergic rhinitis which causes symptoms such as sneezing and a runny nose. Symptoms tend to be worse each morning when you first wake up.
Allergies to animals
Coming into contact with some animals can cause allergic conjunctivitis. This is usually due to allergy to fur or hair.
Giant papillary conjunctivitis
This is uncommon. It is an inflammation of the conjunctiva lining the upper eyelid. It occurs in some people who have a small object on the eye – most commonly, a contact lens. It affects about 1 in 100 wearers of contact lenses. The exact cause of the inflammation is unclear – it is possibly an allergic reaction to debris caught behind a lens or to poor lens hygiene. It also sometimes develops after eye surgery.
Some people become sensitised to cosmetics, make-up, eye drops or other chemicals that come into contact with the conjunctiva. This then causes an allergic response and symptoms of conjunctivitis. In this condition the skin on the eyelids may also become inflamed. It is then called contact dermatoconjunctivitis.
The diagnosis of ocular allergy is primarily clinical, but there are laboratory tests that can be useful in supporting the diagnosis. Allergists can perform skin testing for specific allergens by scratch tests or intradermal injections of allergen. In-vitro tests for IgE antibodies to specific allergens also exist. There are also commercial tests for total IgE levels in tears. Conjunctival smears can provide supportive evidence of ocular allergy. Conjunctival scrapings can be stained with a variety of stains and viewed under light microscopy. Presence of eosinophils, mast cells, or basophils, would support the diagnosis of ocular allergy.
Most people with eye allergies treat themselves and do so quite effectively with OTC products. Most commonly, home care consists of flushing the eye with water. With exposure to an allergen to the eye, it is important to thoroughly flush the eye with lukewarm tap water or commercially prepared eyewash solution. If these remedies are not working or if there is eye pain, extreme redness, or heavy discharge, you should seek medical advice. Some conditions, for example, are serious with potential sight-threatening complications if required treatment is delayed.
Moistening the eyes with artificial tears helps to dilute accumulated allergens and also prevents the allergens from sticking to the conjunctiva. Tear substitutes may also improve the defense function of the natural tear film.
Topical antihistamines & decongestants
Antihistamine eyedrops work by blocking histamine receptors in the conjunctiva. The histamine, therefore, is unable to attach to the conjunctiva and exert its effects. They are effective in relieving itching but have little impact on swelling or redness. They have two advantages over antihistamine tablets; there is a quicker onset of action and less drying of the eye. The new generation of topical antihistamines includes emedastine difumarate (Emadine) and levocabastine (Livostin). The side effects of these medications include mild stinging and burning of the eyes upon use, headaches, and sleepiness. But treatment with antihistamines at the point of irritation is still preferable than treating systemically with oral antihistamines if possible.
Decongestants take the redness away as advertised. However, they do not help relieve itching. They act by shrinking the blood vessels on the conjunctiva. (They are not really effective against allergic eyes.) The decongestants oxymetazdine (Visine LR) and tetrahydrozoline hydrochloride (Visine Original) are available OTC. They do have a potential for abuse and should not be used by people with narrow-angle glaucoma, an eye disease characterized by elevated pressure within the eye.
The prolonged use of decongestant nasal sprays can produce a rebound phenomenon in which the medication begins to cause more congestion than it relieves. This phenomenon rarely occurs in the eyes with the repeated use of decongestant drops. The mucous membranes of the eye are different from those of the nose. The eyes can become irritated and less responsive to the drops, but unlike the nose, the eyes tend not to develop “rebound” redness.
Combination antihistamine-decongestant preparations can provide quick relief that lasts a few hours. They lessen the itch, redness, and swelling and are very useful for milder symptoms. Common combinations include pheniramine with naphcyoline hydrochloride (Naphcon-A or Opcon-A) and antazoline with naphazoline (Vasocon-A). Side effects are minimal, but the drops may become less effective if used for prolonged periods. They do have a potential for abuse and should not be used by people with narrow-angle glaucoma.
Topical mast-cell stabilizers
Mast-cell stabilizers prevent the release of chemical mediators of inflammation from the mast cells. These are effective for all eye allergies. The first of this class of drug was cromolyn sodium (Crolom or Opticrom), which is available OTC. This topical medicine has been effective for treating mild cases of vernal keratoconjunctivitis and probably mild allergic rhinoconjunctivitis and has no significant side effects. It does have a slow onset of action. The newer agent, lodoxamide (Alomide), is 2,500 times more potent than Crolom and has a faster onset of action. This prescription medicine may be used in children older than 2 years of age and has minimal side effects. One disadvantage is the need to use the drops four times a day, and long-term use is necessary to prevent symptoms.
The most effective mast-cell stabilizer, which also has antihistamine properties, is olopatadine (Patanol). Available by prescription, it is 250 times more effective than Alomide in relieving itching and redness. This drug provides rapid relief of itching and burning eyes. It can also prevent symptoms when used before an exposure or before the pollen season. The drops are very comfortable in the eye and can by used in children as young as 3 years old. The longer duration of action allows dosing of twice a day.
Another new product, ketotifen (Zaditor), also has dual mast-cell-stabilizing and antihistamine effects. It dramatically reduces itching and redness and gives more rapid relief within minutes.
Topical antiinflammatory drugs
Nonsteroidal antiinflammatory drugs (NSAIDS) are particularly useful in treating itchy eyes. They reduce redness and swelling to a lesser degree. Ketorolac (Acular) is a topical NSAID, which may cause temporary stinging and burning in 40% of users.
Steroid antiinflammatory eyedrops are very effective in treating eye allergies, but they are reserved for severe symptoms that are unresponsive to other treatments. They must be used with caution in people with bleeding tendencies because they can increase the bleeding risk. Since there are significant risks with long-term treatment, their use should be supervised by an ophthalmologist.
Caution must be taken, however, because of the potential side effects of the long-term use of steroids, even in eye drop form. Side effects of steroids include elevated pressure in the eyes and cataracts. The elevated pressure in the eyes can become glaucoma and lead to damage of the optic (eye) nerve and loss of vision. Cataracts are a clouding or opacification of the clear natural lens within the eye, which can interfere with vision. The purpose of the lens is to focus the light or images that enter the eye. Remember, however, that the side effects of steroids usually occur with long-term use and that steroid eyedrops may be very effective when used over the short term. Loteprednol etabonate (Alrex) is a short-acting steroid with fewer side effects that shows great promise in the treatment of allergic eye disease.
Topical steroids may cause or worsen glaucoma and result in cataracts with long-term use. About 500 drops of a high-dose preparation can cause cataracts. Also, remember that with topical steroid eyedrops, short-term, low-potency preparations are recommended and should only be used under the supervision of an ophthalmologist.
Oral antihistamines, either OTC or prescription (non- or lightly sedating), may be used for itchy eyes. The OTC products may cause drowsiness, and both can cause drying of the eyes.
In general, treating topical conditions with topical medications is preferable.
Allergy shots (immunotherapy)
When avoidance of offending allergens and local treatments are not effective, allergy shots may be indicated. Your allergist may suggest this form of treatment when other measures have been unsuccessful.
Here are a few general tips worth remembering:
- Eyes that are dry may aggravate eye allergy symptoms. Tear substitutes, such as artificial tears, are an often forgotten but are an effective lubricant.
- Cold compresses may help, particularly with sudden allergic reactions and swollen eyes.
- Keep eyedrops refrigerated since this makes application more soothing.
Seasonal and perennial allergic conjunctivitis
Avoidance of the offending antigen is the primary behavioral modification; specific testing by an allergist will identify the responsible allergen(s) and help the individual to establish ways to avoid the allergen. Contact reactions caused by medications or cosmetics are also treated best by avoidance.
As with most type I hypersensitivity disorders, allergen avoidance should be emphasized as the first-line treatment. Although permanent relocation to a cooler climate is not feasible in many cases, it remains a very effective therapy for VKC.
Maintenance of an air-conditioned environment and control of dust particles at home and work may also be beneficial. Local measures, such as cold compresses and periodic instillation of artificial tears, have also been shown to provide temporary relief.
- Don’t touch or rub the eye.
- Use lubricating eye drops or artificial tears to make your eyes feel better.
- Use artificial tears up to 4-6 times a day.
- Try chilling the artificial tears in the refrigerator for an additional soothing effect.
- Wash your hands before using drops.
- Place a cold washcloth over your eyes to reduce the irritation.
The prognosis is favorable for most patients with eye allergies. Typically symptoms clear up quickly with OTC/home treatment or when the offending allergen is not present any more. Unfortunately the symptoms may reoccur depending on the cause of the eye allergy. Complications are very rare, but medical attentions should be sought immediately for any pain or vision loss that occurs or for symptoms that do not resolve within 12 hours.
Complications of perennial or seasonal allergic conjunctivitis are extremely rare. More of a frustration, than a complication, is the recurrence of symptoms. People with pollen allergies may become annoyed with the annual ordeal.
Allergic conjunctivitis is unpleasant. It can disrupt the smooth running of day-to-day life. Concentration may be affected, especially if symptoms are in the eyes – visual data is crucial for concentration. Experts say that allergic conjunctivitis should have no long-term impact on the sufferer’s health.
Complications of dermatoconjunctivitis and giant papillary conjunctivitis
There is a bigger chance of complications with these two types of conjunctivitis. Even though the risk is greater, it is still small.
There is a risk that the cornea may become inflamed (keratitis). Keratitis can cause ulcers to form on the cornea, significantly raising the risk of scarring, which can cause permanent impairment of vision. Symptoms of keratitis are:
- Intense pain in the eye
- Sensitivity to light (photophobia)
- Blurred vision
- A feeling that there is something in the eye
- Watery eyes.