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Allergic Conjunctivitis

Editor: Eilene E. Kinzer Updated: 5/23/2022 7:26:43 AM


Allergic conjunctivitis is a common, under-appreciated, and largely benign process. It is rarely vision-threatening but can significantly decrease the quality of life for patients. There are three subtypes of simple allergic conjunctivitis: acute, seasonal, and perennial. There is considerable overlap with atopic conjunctivitis (vernal and atopic keratoconjunctivitis) and giant papillary conjunctivitis in both treatment and certain aspects of pathophysiology. As such, these are all considered to be ocular allergies. Initial treatment strategies can be similar, although outcomes and rates of complications vary.[1][2][3]


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Simple Allergic Conjunctivitis: Most cases are secondary to simple allergen exposure on the ocular surface.

Vernal Keratoconjunctivitis: Exact etiology is not well understood, but some combination of climate and allergen is believed to be responsible.

Atopic Keratoconjunctivitis: Etiology is not clear but appears to be a combination of allergen exposure, atopic dermatitis (more than 90% of cases), and\or genetic predisposition.

Giant Papillary Conjunctivitis: Allergen exposure and subsequent response secondary to the ocular foreign body either harboring allergens on its surface or injuring ocular structures that facilitate allergen infiltration. It can be seen with many different ocular foreign bodies (e.g., contact lenses, prostheses, cyanoacrylate glue, sutures).


Simple Allergic Conjunctivitis: It is difficult to estimate how many patients are affected as the symptoms are often under-appreciated, and many patients go without seeking medical care. Simple ocular allergy likely affects between 10% to 30% of the general population. In most cases, onset occurs in patients younger than 20 years old, decreasing prevalence in older populations. Allergic conjunctivitis can be seen as an isolated finding but is often associated with allergic rhinitis, atopic dermatitis, and/or asthma.

Vernal Keratoconjunctivitis: More commonly seen in males (ratio between 2 to 1 and 3 to 1) in dry, warm climates. Most cases occur in patients younger than ten who often have a history of atopy or asthma. Many patients have complete resolution without the return of symptoms after adolescence.

Atopic Keratoconjunctivitis: Not usually seen before adolescence and peaks from 30 to 50 years of age. Most cases are seen in patients with atopic dermatitis. Like vernal keratoconjunctivitis, there is a male to female predominance (between 2 to 1 and 3 to 1)

Giant Papillary Conjunctivitis: Seen most commonly in teens and young adults, most likely because of a temporal relationship with contact lens use. It is most commonly seen in conjunction with soft contact lens use and is present in approximately 5% of that population. The average onset is one to two years after starting soft contact lenses but varies widely with other ocular foreign bodies.[4][5][6]


Simple allergic conjunctivitis (acute, seasonal, and perennial) is an immunoglobulin E (IgE) mediated hypersensitivity reaction (type I) and resultant mast cell degranulation secondary to direct contact with an allergen to the ocular surface. As such, there is an immediate and delayed phase of the reaction mediated by different inflammatory modulators. The exact mechanism involved in vernal keratoconjunctivitis is not well understood. Still, there is likely an IgE mediated hypersensitivity and T cell involvement in the reaction. Atopic keratoconjunctivitis appears to be a combination of delayed-type (type IV) and immediate (type I) hypersensitivity to an ocular allergen exposure. Giant papillary conjunctivitis occurs secondary to direct mechanical irritation/injury and subsequent immune response (type I and type IV). The foreign object may become coated with different allergens or injury epithelial tissue and allow deeper exposure to allergens and provoke an immunological response.[7][8]


Vernal Keratoconjunctivitis will show an accumulation of eosinophils, mast cells, and proliferation of fibroblasts. Biochemical stains will reveal the presence of proteases, chymase, and tryptase. The substantia propria is thickened due to collagen deposition. Both T and B lymphocytes are present, which release IgE and IgG. The overall picture resembles both type 1 and type IV hypersensitivity reactions.

Atopic keratoconjunctivitis will also show a slight increase in eosinophils and mast cells. Tears will contain high levels of IgE. The picture resembles Type 1 hypersensitivity.

Giant papillary conjunctivitis will reveal infiltration of many white cell types, including plasma cells, mast cells, lymphocytes, basophils, and eosinophils. Elevated levels of IgE are found in tears.

History and Physical

Allergic conjunctivitis frequently accompanies seasonal allergy symptoms, specifically known allergy exposures or a history of atopy. As such, recurrent episodes are commonly seen. Practitioners should elicit a personal history of allergies and atopy and a history of similar episodes in the past. Practitioners should ask about specific symptoms from the current and any past episodes. Itchiness and diffuse bulbar and tarsal conjunctival injection are the most commonly reported symptoms and present in allergic conjunctivitis subtypes. Other histories and physical exam findings vary with the specific subtype of allergic conjunctivitis.

Simple Allergic Conjunctivitis: Clear, watery discharge is the most commonly seen discharge and is usually bilateral with minimal crusting in the mornings. Pain and decreased visual acuity are not commonly reported in simple allergic conjunctivitis and should prompt the provider to consider another diagnosis. Eyelid edema and chemosis are not uncommon and can be quite marked.

Vernal Keratoconjunctivitis: Symptoms are usually most severe in the spring and include thick mucus discharge, pain, photophobia, and blurred vision. Patients will also often complain of foreign body sensation. On examination, corneal ulcers and conjunctival infiltrates can sometimes be found. Giant papillae on the tarsal conjunctiva are universally seen on examination.

Atopic Keratoconjunctivitis: Symptoms are usually perennial and include pain, blurry vision, photophobia, and foreign body sensation. Examination reveals findings similar to simple allergic conjunctivitis. The addition of chronic inflammatory changes to the ocular surface (corneal scarring and neovascularization) and varied changes to the eyelids (lower lid more commonly) and peri-orbital skin range from mild atopy to lichenification.

Giant Papillary Conjunctivitis: Symptoms consistent with simple allergic conjunctivitis often give way to worsening itch and discharge that becomes thick mucus instead of clear and watery. Patients usually report worsening pain and blurry vision with the increased sense of foreign body (contact lenses, sutures). The examination reveals findings consistent with simple allergic conjunctivitis as well as giant papillae covering the tarsal conjunctiva.


The diagnosis is made clinically with a thorough history and classic physical examination findings. If there is any concern based on the history and physical examination, fluorescein staining of the cornea can ensure no corneal abrasion. Laboratory testing is generally not needed, although skin prick or serum allergy testing can help mitigate the disease process by identifying the offending allergens so that they can be avoided if possible.[3][9]

Treatment / Management

Simple allergic conjunctivitis: All patients should be educated about general allergic eye care. They should be discouraged from rubbing their eyes, which causes mast cell degranulation and worsening of symptoms. They should be asked to apply artificial tears and cool compresses frequently. If possible, they need to avoid known allergen exposures and remove contact lenses (if applicable). Mild acute forms can be treated over-the-counter antihistamines or antihistamine and vasoconstrictor combination drops for relatively short periods. The patient should be warned against mild rebound conjunctival injection if they use a drop with a vasoconstrictor. Seasonal and perennial allergic conjunctivitis should receive combination antihistamine and mast cell stabilizing drops. Topical nonsteroidal anti-inflammatory drops are more effective than placebo but far less so than antihistamine/mast cell stabilizing drops. For refractory cases, corticosteroid drops are a viable option in short bursts (less than two weeks) in conjunction with a specialist consultation and follow-up. Systemic antihistamines and steroids also have a limited role in refractory cases and cases where the patient has systemic, as opposed to isolated ocular, symptoms.[10][11][12]

Vernal and Atopic Keratoconjunctivitis: Patients should be given the same education about general allergic eye care (avoid rubbing eyes, use artificial tears and cool compresses, avoid allergen exposure) as simple allergic conjunctivitis.  Initial pharmacotherapy is similar to seasonal and perennial allergic conjunctivitis with topical combination antihistamine/mast cell stabilizing drops. Refractory cases should be referred to a specialist who can prescribe topical corticosteroids. If the patient continues to be refractory or cannot be weaned from topical steroid therapy, topical or systemic calcineurin inhibitors can be used.

Giant Papillary Conjunctivitis: First item of management is to remove the mechanical irritant, which is most commonly a contact lens. Patients should be educated and begin the same general allergic eye care used in other subtypes of ocular allergy (avoid rubbing eyes, use artificial tears and cool compresses, avoid allergen exposure). Initial pharmacotherapy is similar to other ocular allergies, for example, topical antihistamine or combination antihistamine and mast cell stabilizing drops. In conjunction with a specialist, topical corticosteroid drops are used in refractory cases (similar to vernal and atopic keratoconjunctivitis), but calcineurin inhibitors have no role in treatment.

Differential Diagnosis

  • Viral conjunctivitis
  • Bacterial conjunctivitis


In most patients, the prognosis is good. Complications are rare, but recurrence of symptoms is not uncommon. For patients who sustain corneal damage, this may be associated with visual loss. The medications used to manage allergic conjunctivitis may sometimes also induce cataracts.


In most cases, allergic onjunctivitis does not present a serious health threat.

Complications of allergic conjunctivitis are rare, but when they do occur, they can be serious and include:

  • Severe cases can result in scarring of the eye.
  • If allergic conjunctivitis progresses to infective conjunctivitis, the infection can spread to other areas of the body, potentially causing serious secondary infections.

Deterrence and Patient Education

Prevention is the key, and this means making lifestyle changes. Today, many allergists can perform skin tests to identify the allergen, allowing one to make a long-term preventive strategy.

Enhancing Healthcare Team Outcomes

The majority of patients with allergic conjunctivitis are first seen by the pharmacist, nurse practitioner, or primary care provider. The patients may be in the pharmacy searching for an over-the-counter treatment; the pharmacist should take this opportunity to educate the patient on lifestyle changes and refer the patient with serious/recurrent symptoms to an ophthalmologist.

Patients with allergic conjunctivitis need to avoid the offending antigen, which requires lifestyle changes. Some patients may need to undergo allergy tests to determine the allergen and then make the behavior changes. Often the wearing of contact lenses may not be possible. In all cases, the patients should receive education on humidifying the home, wearing sunglasses when going out, avoiding mascara and makeup, using artificial tears liberally, and applying cold compresses to the eye.[13][14][15]

While the primary care provider and nurse practitioner may see patients with allergic conjunctivitis as outpatients, they should always be alert for patients with visual changes or severe symptoms. Empirical prescription of topical steroids by the primary care providers is not recommended as these agents can also cause cataracts; referral to an ophthalmologist is prudent.

It is always possible that allergic conjunctivitis is mistaken for a much more serious disease. As a result, the nurse and pharmacists dealing directly with the patient need to be vigilant and report to the clinical team interprofessional leader, the ophthalmologist, or optometrist if they are not improving relatively quickly. The pharmacist and nurse should similarly provide patient education and inform them that close follow-up is necessary if improvement does not occur quickly. The development of pain is always a disconcerting symptom and should require the team to report to the team leader. An interprofessional approach that involves open communication and joint education will result in the best care. If the interprofessional team works together to identify potential treatment failures before developing significant morbidity, potential poor outcomes can be avoided. [Level 5]


PAC and SAC's long-term outcomes are good, but a significant number of people are left with eye discomfort and poor ocular cosmesis. Some individuals develop recurrences leading to conjunctivochalasis-which is secondary to ongoing limbal conjunctival chemosis. Other complications that can occur in VKC and AKC include corneal opacification and ulcer formation. Some patients may develop lid involvement leading to difficulty in wearing contact lenses. Overall, allergic conjunctivitis management also leads to time off work and an increased cost of care because of frequent visits to the eye specialist and the need to buy prescription eye drops. Finally, drugs used to manage allergic symptoms may also lead to adverse reactions like cataracts.[16][17] [Level 5]


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Allergic Conjunctivitis
Allergic Conjunctivitis
Contributed by Katherine Humphries, MD



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