The key to instilling drops in children is to not frighten or trick them. But once you broach the subject, be ready to instill the drops. The longer you wait, the harder it will be.

We see patients with external allergic reactions almost every day. This isn’t surprising, considering it occurs in an estimated 20% to 25% of the population—and in up to 40% of children.¹ But confirming and then treating a diagnosis of allergy is more difficult in children, for all the obvious reasons. Because we need to differentiate and diagnose allergic presentations with such frequency, here is a brief review of allergic conjunctivitis revolving around the pediatric population.

Pathophysiology
Allergic reactions generally arise from prior exposure to an allergen, resulting in sensitization. Upon re-exposure, allergen-specific IgE antibodies bind to receptor sites in mast cells. This causes a release of chemical mediators from the mast cells and mast cell degranulation. While there are a number of agents released from the mast cells, histamine plays a major role in the “immediate allergic response,” resulting in increased vascular permeability, chemosis and redness.²

With degranulation there is some degree of accompanying inflammatory response, with IgE cross-linking leading other mediators to recruit cells for a “late allergic response,” some six to 12 hours later.

The allergic immune response is complex and, in children, may begin before a baby is born. Allergic disease in infants is influenced by the maternal immune response during pregnancy. Genetic, environmental, nutritional and immunologic factors during pregnancy play a role in a child’s propensity to develop allergic sensitization and subsequent allergic disease.³

What’s the Diagnosis?
As always, making the appropriate diagnosis leads to the best choice of treatment. This is no different for allergic disease in children. Children have active immune systems, and allergic reactions in children, with varied presentations, are quite common. We must first differentiate allergic disease from viral, bacterial and dry eye presentations. (See “Basic Differential Diagnoses for Ocular Allergy.”) Then, we must differentiate the type of allergic reaction. Most ocular allergic reactions (greater than 80%) are mild, but allergic reactions can range from mild to severe conditions, such as atopic keratoconjunctivits and vernal conjunctivitis, which can have more serious consequences.

Basic Differential Diagnoses for Ocular Allergy
	Allergy	Viral	Bacteria	Dry Eyes
History	allergen exposure	upper respiratory infection	other family member	systemic disease
Duration	often chronic	recent onset	acute recent onset	chronic
Symptoms	itching	foreign body sensation, irritation, pain	irritation, low-grade pain	sandy, foreign body sensation
Hyperemia	mild to moderate	often moderate to marked	moderate to marked	mild
Discharge	watery, stringy	watery	mucopurulent	tearing
Papilla	marked	mild	mild to moderate	minimal to mild
Follicles	moderate	moderate to marked	varied	minimal to mild

• History. Differential diagnosis starts with history. Admittedly, history can be misleading, with the limitation that it must sometimes be obtained from the parents, but it can lead directly to the correct diagnosis. Remember that none of the following is a rule inviolate, only a general guide.

Ask pointed questions to obtain specific answers. A history of exposure to a known allergen for that patient—for example, “My daughter was playing with her friend’s Persian cat”—can lead to a diagnosis of acute allergic conjunctivitis. The history that “my child gets red watery eyes every year at this time,” can lead to a diagnosis of seasonal conjunctivitis (associated with seasonal exposure to known allergens). The history that “my child’s eyes are red and tearing all year long,” can lead to a diagnosis of chronic allergic conjunctivitis (with the known or unknown allergen being environmental in nature). Kids who suffer from perennial allergic conjunctivitis often have a history of allergic rhinitis, atopic dermatitis and/or asthma.

Because most viral and bacterial conjunctivitides are of limited duration, the chronicity of the problem may point to allergy—unless you can locate a source of re-infection, such as in canaliculitis or chronic blepharitis.

While dry eye in children may cause long-term problems, there usually is an associated systemic etiology or the presence of chronic blepharitis.

Although only about 1.5% of healthy children have dry eye symptoms, the presence of a symptom such as burning is an indication of possible systemic disease.⁴ A health history of systemic disease, such as rheumatoid juvenile arthritis or Sjögren’s syndrome, may point to dry eye, but a history of asthma or atopic dermatitis may lend credence to a diagnosis of an allergic etiology. Conversely, a history of recent upper respiratory infection, or of a recent eye infection in a sibling, may point to a bacterial or viral etiology.

• Patient symptoms. The symptoms presented aid diagnosis as well. Complaints of itching are strongly associated with allergic conjunctivitis, while complaints of burning and foreign body sensation are associated with dry eye. Complaints of lids matted together, along with irritation and soreness, point to a bacterial etiology. Irritation and pain suggest a viral etiology. Photophobia is more commonly associated with the corneal involvement seen with viral etiologies.

Remember that allergic conjunctivitis is almost always bilateral, while viral conjunctivitis is bilateral but often asymmetric, and bacterial conjunctivitis can be unilateral. The bilateral symmetry of dry eye problems in children vary based on the etiology.

In short, symptoms of itching with a stringy and watery discharge suggest allergy. Watery discharge and photophobia suggest a virus. Mucopurulent discharge suggests a bacterial cause. And, dry eye is usually accompanied by tearing.

• Clinical signs. The diagnosis of allergic conjunctivitis is a clinical decision that is not based on laboratory findings. So, the clinician must garner a series of careful observations to construct a presentation, which then leads to the appropriate diagnosis.

In acute allergic conjunctivitis, bilateral lid edema is common in association with marked conjunctival chemosis. Bilateral lid edema is also seen with viral conjunctivitis, but usually with a lesser degree of conjunctival chemosis. As with many allergic diseases, clinical manifestations decrease with age. Thus, chronic allergic conjunctivitis leads to milder lid edema and conjunctival chemosis over time. Kids who suffer from chronic allergic conjunctivitis can develop dark discoloration below their eyes, called allergic shiners.

If possible, evert and inspect the upper lid. This may not be possible with all children, of course. But, if you pull up the lid high enough and you look from down below, you can often get an idea of the underlying conjunctival mosaic. Children with allergic conjunctivitis usually show a marked papillary reaction, but also demonstrate some follicles. The absence of petechial conjunctival hemorrhages—as is sometimes seen in viral disease or in association with the vascular fragility caused by some bacteria—helps to rule against an infectious etiology.

Pay careful attention to the papillary reaction, as the degree of the reaction can point to a more serious diagnosis. Severe papillary reaction asymmetrically involving the upper tarsal plate may indicate vernal conjunctivitis.

Vernal conjunctivitis is a recurrent seasonal disorder seen most frequently in young males and more prevalent in warmer climates.⁵ It is characterized by an extensive papillary reaction disproportionately involving the upper tarsal conjunctiva, limbal involvement with the accumulation of eosinophils and cellular debris forming yellow/white mounds (Horner-Trantas dots), and may lead to corneal neovascular intrusion and the development of a sterile corneal shield ulcer (so called because of its shape).

Atopic conjunctivitis often starts at a young age, but can be seen in the pediatric or adult population. It is seen in association with asthma and atopic dermatitis. Check the periocular skin and lids for an atopic reaction, such as redness, blisters, drying or thickening with a superficial crusting rash. There is a marked papillary reaction, which sometimes is manifested more inferiorly.

Hyperemia is typical in any form of conjunctivitis. In the common form of allergic conjunctivitis, it is usually mild. Marked hyperemia is more common in viral and bacterial conjunctivitis.

Corneal involvement in allergic conjunctivitis is most often minimal or limited to superficial punctate keratopathy. In the rare extremes of vernal or atopic disease, corneal involvement is significant, with the potential for a permanent effect on vision.

What’s the Treatment?
Making the appropriate diagnosis directs us to the appropriate course of treatment. Remember, prevention or avoidance of the allergen is always the first and usually the most effective course of action. For children who are allergic to cat dander, do not let them play with cats. For children with seasonal allergies, try to limit their exposure to known allergens—is going to the botanical garden really a good idea at this time in the season? For children with chronic allergy, consider removing potential environmental allergens of dust mites or mold spores.

Once exposed, the treatment reflects the severity of the presentation.

• Mild presentations. For mild allergic presentations, artificial tears and cool compresses work well. The artificial tears help flush allergens out of the eye, and decrease rubbing by increasing comfort. Cool compresses decrease swelling and blood flow to the area, thereby inhibiting the allergic response. Artificial tears and cold compresses do not treat the underlying allergic response, but can provide relief from ocular symptoms in mild cases. This may be the most appropriate choice for very young children under age two when there is no pediatric-approved topical ophthalmic drug.

Topical vasoconstrictors are of limited value, although more effective when used in combination with a topical antihistamine. Mast cell stabilizers prevent degranulation, thus interrupting the allergic cascade at a later point. This also means that mast cell stabilizers have a slower onset of action—typically five to 14 days.² For this reason, they are best used in advance of the known approach of seasonal allergic conjunctivitis.

• Moderate presentations. Today, the mainstay of treatment is the family of combination antihistamine-mast cell stabilizers. A number of these medications are available, most approved for children age three and older, and two approved for children as young as two years of age. These have a rapid therapeutic onset, and they can be safely used over an extended period of time. They provide effective relief for most forms of allergic conjunctivitis. (See “Topical Ophthalmic Anti-allergy Medications.") Allergy meds with daily or twice-daily dosing obviously are better for both kids’ and parents’ schedules.

Antihistamine is the fast-acting component and the mast cell stabilizer is slower acting but prevents the allergic cascade from occurring. For those children who suffer yearly from seasonal allergies, starting a topical antihistamine-mast cell stabilizer six weeks ahead of allergy season can often prevent a child from having seasonal ocular allergic reactions.

• Severe presentations. The use of steroids is reserved for when it is clearly indicated, such as for acute and chronic forms of allergic conjunctivitis, and then only for a limited period. A topical steroid may help the patient with a marked reaction to an allergen (i.e., acute allergic conjunctivitis) more rapidly regress toward a normal baseline.

Acute reactions can be treated with a steroid for a short period of time, usually three to five days. This can then be followed up with the use of an antihistamine-mast cell stabilizer. In seasonal chronic disease, breaking the cycle of allergic reaction may take longer, requiring steroids for seven to 10 days.

In the more severe forms of allergic conjunctivitis, such as vernal or atopic keratoconjunctivits, the use of a mild steroid, such as fluorometholone or loteprednol, is indicated.⁶ In these cases, we must increase comfort and delimit the progression of these diseases as quickly as possible. Treat with a steroid for seven days at minimum; however, the steroid may be required for even longer—two weeks or more—to reach a reasonable baseline. After improvement of symptoms, you can switch the patient to an antihistamine-mast cell stabilizer combination drop.

With adjunctive corneal involvement, an aggressive approach is warranted (e.g., concurrent use of prednisolone eye drops q.i.d. and a topical antibiotic drop as indicated).⁵ When there are concurrent signs of allergy, such as conjunctival chemosis or eyelid edema along with itching, use steroids.

Be mindful, as always, of the steroid’s adverse effects, including increased intraocular pressure, viral infections and cataract formation.

While allergic eye disease is most often not serious or vision threatening in nature, it can profoundly affect a child’s quality of life (and the parents’ as well).

Considering its prevalence in the pediatric population, it’s up to us to recognize these signs and symptoms, and intercede in an appropriate manner.

Dr. Thau is the owner of a group practice in New York, which has a special emphasis on children’s vision and vision therapy. She is a Trustee of the American Optometric Association and a founder of AOA’s InfantSEE public health program. She is also an associate clinical professor at the SUNY College of Optometry. Dr. Chung is an associate professor at SUNY, specializing in pediatric optometry. She is president-elect of the College of Optometrists in Vision Development. Dr. Richter is an associate professor at SUNY within the Pediatric, Infant’s Vision and Ocular Disease Services.

1. Abelson MB, Granet D. Ocular allergy in pediatric practice. Curr Allergy Asthma Rep. 2006;6(4):306-11.
2. Rosario N, Bielory L. Epidemiology of allergic conjunctivitis. Curr Opin Allergy Clin Immunol. 2011;11(5):471-6.
3. Warner JA. Primary sensitization in infants. Ann Allergy Asthma Immunol. 1999 Nov;83(5):426-30.
4. Kotaniemi KM, Salomaa PM, Sihto-Kauppi K, et al. An evaluation of dry eye symptoms and signs in a cohort of children with juvenile idiopathic arthritis. Clin Ophthalmol. 2009;3:271-5.
5. Dimov V. Ocular allergy: Allergic conjunctivitis and related conditions, brief review. Updated Feb. 2, 2012. Available at: http://allergycases.org/2005/02/ocular-allergy-allergic-conjunctivitis.html. Accessed June 13, 2012.
6. Bielory L, Katelaris CH, Lightman S, Naclerio R. Treating the ocular component of allergic rhinoconjunctivitis and related eye disorders. Medscape General Medicine. 2007;9(3):35. Available at: www.medscape.com/viewarticle/560750_5. Accessed July 29, 2012.