Each of us sees patients who present with itchy eyes. Often this symptom is the only apparent problem these patients have. But before we arbitrarily choose a drop to stop the itch of allergic conjunctivitis, we need to understand the pathology of the allergy. That understanding will enhance our treatment success and the comfort of our patients, as this month's case shows.

THE CASE: It was obvious from across the room that Cathy's red, puffy eyes were in rough shape. She told me that 3 days earlier, her eyes had begun to itch and tear. Since then, the symptoms had rapidly progressed to the point where Cathy wanted "to rub my eyeballs out of my head."

She told me that the itching had worsened and now her eyes hurt; lights bothered them, too. I asked her about discharge. She said that she had a mild amount of "stringy stuff" throughout the day. Occasionally, the mucus blurred her vision.

Cathy suffered from seasonal allergies that had progressed to the point where there was no more off-season. She used mometasone furoate (Nasonex Nasal Spray) qd and fexofenadine (Allegra) b.i.d. to control her allergic symptoms. Her eyes had still itched and teared sometimes, but never as badly as they did now. Cathy also took oral contraceptives. She'd worn soft contact lenses for 10 years but not for the past 9 months due to ocular discomfort.

Examining Cathy's eyes

With her myopic correction, Cathy saw 20/20-2 OD and 20/25 OS. This didn't improve with the pinhole occluder or a refraction. External examination was normal. When I evaluated Cathy with a slit lamp, I discovered a host of problems.

The lids of both eyes were slightly edematous with mild lid debris OU. The bulbar conjunctiva showed Grade 2 injection OU, and Grade 2 papillae appeared on the upper and lower palpebral conjunctivae in each of Cathy's eyes.

Long mucus strands were present in the inferior fornix of each eye. These strands sometimes migrated onto the surface of the eyes and remained there through a few blink cycles. They were easily removed with a moist cotton swab.

Even without a slit lamp, I saw that that Cathy had excessive amounts of tears. I applied sodium fluorescein dye (NaFl) using a sterile strip. The dye highlighted a lacrimal lake greater than 2 mm in height OU and a great deal of corneal staining. Small superficial punctate-type staining defects were evident diffusely throughout both of Cathy's corneas. The remainder of her exam, including the fundus, optic nerve and tonometry, was normal.

From her symptoms and clinical findings, I felt that Cathy had severe allergic conjunctivitis.

The immunology of allergy

An allergic reaction is an organ's exaggerated immune response to a foreign substance, or antigen like pollen, cat dander, smoke or molds. The body recognizes these antigens as "non-self" and marks them with immunoglobulins specific for each antigen. The immunoglobulins present the antibodies to certain cells on an organ and begin a "self versus non-self" reaction, which triggers the inflammatory cascade.

IgE is the immunoglobulin that's most responsible for this process in the eye. IgE is found in minute concentrations on the goblet cells of the conjunctiva. It binds to mast cells on the conjunctival surface. When sensitized, IgE causes the mast cells to degranulate. This then causes the release onto the ocular surface of the chemical mediators that cause allergy symptoms, including prostaglandins and leukotrienes and platelet activating factor.

As the allergic response proliferates, more mediators are released and the clinical presentation worsens, with redness, mucus, swelling and itchiness.

Playing the options

Treatment for ocular allergic conditions entails not only treating the symptoms but also short-circuiting the inflammatory cascade. To choose the most appropriate therapy, you must understand how each topical drug does this. Here's an explanation:

�         Mast cell stabilizers. These agents prevent the further release of chemical mediators by preventing degranulation of mast cells. They don't have any effect on the histamine already released; thus, their therapeutic action is delayed, which limits their use in acute cases. They're useful in chronic conditions. Examples include cromolyn sodium (Opticrom) and pemirolast potassium 0.1% (Alamast).

�         Topical antihistamines. These work well in acute cases of allergic disease. These agents bind to histamine receptors on the ocular surface, blocking histamine from these sites and diminishing the histamine response rapidly and effectively. The new generation topical antihistamines, which include olopatadine HCl (Patanol) and ketotifen (Zaditor), work like combination drugs. Olopatadine and ketotifen possess mast-cell-stabilizing capabilities and have secondary anti-inflammatory properties, which enhance their usefulness.

�         Non-steroidal anti-inflammatory drugs (NSAIDs).Helpful against severe ocular allergies, NSAIDs affect the inflammatory cascade and prevent prostaglandin formation, which limits inflammation and makes the patient more comfortable. Examples include: diclofenac sodium (Voltaren Ophthalmic) and ketorolac tromethamine (Acular).

�         Topical steroids. Topical steroids work as NSAIDS do, and are useful in more severe cases. Ocular steroids also limit inflammation by short-circuiting the inflammatory cascade. They're useful in severe allergic conjunctivitis and when there's corneal involvement.
"Soft steroids" don't cause intraocular pressure increase or corneal melting and are good in short bursts for very uncomfortable patients. They include loteprednol etabonate (Alrex), rimexolone 1% (Vexol) and fluorometholone acetate 0.1% (eFlone). They should be used q.i.d. to q4h initially and then tapered quickly when symptoms have subsided.

To the rescue

Cathy's condition was severe, so I had to treat it aggressively.

To quiet the corneal inflammation and dampen the symptoms, I prescribed loteprednol etabonate OU q4h. I also urged Cathy to continue the mometasone furoate and fexofenadine. I re-examined her in 5 days, and she felt much better. She had no more superficial punctate keratitis. The redness had decreased to a grade 1, and the mucus discharge had ended. Papillae were still present.

The steroid had defused the inflammatory cascade, so I tapered her off it over the next week. In its place I prescribed ketotifen OU b.i.d. to minimize the effect of histamine. I'll see her in another week to assess the effectiveness of the ketotifen. If she's not as comfortable as before, I'll try another topical antihistamine or an NSAID.

Cathy will remain on whichever agent makes her most comfortable. I've also referred her to an allergist to check her systemic treatment.

Seeing the light

Allergic conjunctivitis conditions are among the most common cases you'll see.

Understand what's going on and decide what you want to treat so your success rate will improve.

Contributing Editor Eric Schmidt, O.D., is director of the Bladen Eye Center in Elizabethtown, N.C.

CLINICAL PEARLS

More than 50 million people suffer from ocular allergies. Seasonal allergic conjunctivitis (SAC) is the most common presentation. Here are some tips to aid you in caring for patients with SAC.

�         The symptoms may be much more severe than the clinical signs.

�         Treatment depends upon the severity of both the clinical signs and symptoms.

�         Prescribed eyedrops are safer and more effective than over-the-counter remedies.

�         Make the patient aware that treatment may be prolonged.

�         Allergy patients require frequent follow-up.

�         Patients with chronic allergic conjunctivitis probably need systemic antihistamine therapy as well.

�         Punctal occlusion has been shown to diminish symptoms in chronic SAC patients.

�         Remember that SAC isn't always seasonal. It can be a chronic disease.