Eye Allergy (cont.)
In this Article
- Eye allergy introduction
- What is the basic anatomy of the outer eye?
- Why are the eyes an easy target for allergies?
- What are allergic eye conditions?
- What are eyelid allergies (also called contact eye allergies)?
- What conditions can be confused with eye allergies?
- How do we care for allergic eyes?
- Eye Allergy At A Glance
- Eye Allergy Glossary
- Eye Allergy Index
- Find a local Asthma & Allergy Specialist in your town
How do we care for allergic eyes?Most people with eye allergies treat themselves and do so quite effectively with OTC products. 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.
Allergy assistAvoid the triggers
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.
Avoidance is once again the cornerstone of allergy treatment. It is particularly important to avoid both airborne and contact allergens. Remember, rubbing your eyes is a physical trigger and therefore must be avoided.
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.
Allergy assistCombination 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.
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.
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 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 new short-acting steroid with fewer side effects that shows great promise in the treatment of allergic eye disease.
Allergy alertSystemic medications
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.
Allergy assistAllergy shots (immunotherapy)
In general, treating topical conditions with topical medications is preferable. Why involve the whole body when locally effective alternatives are available?
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 and a wonderful treatment.
- Cold compresses may help, particularly with sudden allergic reactions and swollen eyes.
- Keep eyedrops refrigerated since this makes application more soothing.
- Most allergic eye conditions are more irritating than dangerous.
- Allergic or vernal keratoconjunctivitis may result in scarring of the cornea and visual problems.
- Itchy eyes are probably allergic eyes.
- Topical antihistamine/decongestant preparations are effective and safe for mildly itchy, red eyes.
- Patanol, a topical mast-cell stabilizer, is a safe, highly effective, long-acting treatment.
- Topical steroids should be used with caution and under the supervision of an ophthalmologist.
- If in doubt, seek medical advice sooner rather than later.