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Allergic conjunctivitis

Updated : January 1, 2024





Background

  • Allergic conjunctivitis is a prevalent ocular condition distinguished by the inflammation of the conjunctiva, a transparent membrane enveloping the front part of the eye and the inner surface of the eyelids. This condition arises when the conjunctiva is exposed to an allergen, leading to the activation of the immune system. 
  • The identification of allergic conjunctivitis typically relies on a comprehensive evaluation of the patient’s medical background and meticulous clinical examination. The onset of an allergen sets off an allergic reaction, thus, the fundamental behavioral adjustment for all forms of allergic conjunctivitis involves avoiding exposure to the triggering allergen. Apart from this, the management of allergic conjunctivitis differs to some extent based on the particular subtype. Various medications such as mast cell stabilizers, topical antihistamines corticosteroids and nonsteroidal anti-inflammatory drugs, can be employed for the treatment of allergic conjunctivitis. 

Epidemiology

  • Simple Allergic Conjunctivitis: It is estimated that a significant number of individuals, approximately 10% to 30% of the total population, experience a common ocular allergy. In general, symptoms tend to manifest in individuals below the age of 20, while their occurrence decreases in older age groups. Although allergic conjunctivitis can manifest as a standalone condition, it is frequently linked to atopic dermatitis, allergic rhinitis, and/or asthma. 
  • Vernal Keratoconjunctivitis: This condition is more commonly found in males, with a ratio of occurrence between 2:1 and 3:1, particularly in dry and hot climates. It primarily affects individuals under the age of ten, often with a background of atopy or asthma. 
  • Atopic Keratoconjunctivitis: Typically, this condition is not observed before adolescence and reaches its peak between the age of 30 to 50 years. Atopic dermatitis is commonly observed in most cases. Like vernal keratoconjunctivitis, there is a higher prevalence among males compared to females (with a ratio lies between 2:1 and 3:1). 
  • Giant Papillary Conjunctivitis: This condition is most seen in teenagers and younger individuals, which is likely due to its temporal association with the use of contact lenses. It is primarily observed in individuals who use soft contact lenses and affects around 5% of that population.  

Anatomy

Pathophysiology

  • Sensitization: Initially, the individual is exposed to an allergen, such as pollen, pet dander, dust mites, or certain chemicals. These allergens are usually harmless substances, but in susceptible individuals, the immune system recognizes them as foreign and mounts an allergic response. During the first exposure, the allergen is recognized by antigen-presenting cells (APCs), which capture the allergen and present it to T-helper lymphocytes. 
  • Activation of T-helper cells: The allergen presentation by APCs activates T-helper cells, specifically type 2 T-helper cells (Th2). This leads to the release of cytokines, such as interleukin-4 (IL-4), interleukin-5 (IL-5), and interleukin-13 (IL-13). 
  • IgE production: The cytokines released by Th2 cells stimulate B-lymphocytes to produce specific IgE antibodies against the allergen. These IgE antibodies have a high affinity for receptors found on mast cells and basophils in the conjunctiva. 
  • Sensitized mast cells and basophils: The IgE antibodies bind to the receptors on mast cells and basophils, sensitizing them to subsequent exposure to the allergen, Sensitized mast cells and basophils are now primed for an allergic reaction.

Etiology

  • Simple Allergic Conjunctivitis: Most cases result from exposure to allergens on the surface of the eye. 
  • Vernal Keratoconjunctivitis: The exact cause is not well known, yet it is likely to be a combination of climate and allergen exposure. 
  • Atopic Keratoconjunctivitis: The cause is not clearly defined, but allergen exposure, atopic dermatitis (found in over 90% of cases), and possibly genetic predisposition. 
  • Giant Papillary Conjunctivitis: It occurs when an ocular foreign body, such as contact lenses, prostheses, cyanoacrylate glue, or sutures, meets the eye and triggers an allergic response. The foreign body may carry allergens on its surface or cause damage to ocular structures that facilitate allergen infiltration. 

Genetics

Prognostic Factors

  • Allergen exposure: The type and level of exposure to allergens play a crucial role in the development and progression of allergic conjunctivitis. A higher exposure to allergens can lead to more severe and prolonged symptoms. 
  • Duration of exposure: The exposure time to allergens can impact the severity of allergic conjunctivitis. Chronic exposure to allergens, such as in individuals with year-round allergies, may result in long-term or recurrent symptoms. 
  • Coexisting conditions: The presence of other allergic conditions, such as allergic rhinitis (hay fever) or asthma, can influence the prognosis of allergic conjunctivitis. These conditions often coexist and can contribute to more severe and persistent symptoms. 
  • Age: Allergic conjunctivitis often develops in childhood and may improve or resolve as a person ages. The children of Younger age tend to have a better prognosis than older adults. 

Clinical History

  • Age Group: 
  • Allergic conjunctivitis can affect individuals of any age group. More in young adults. Children are particularly susceptible to allergic conjunctivitis due to their developing immune systems and increased exposure to allergens in their environment. 

Physical Examination

  • Seasonal and perennial allergic conjunctivitis 
  • Common indications of allergic conjunctivitis include dilation of the blood vessels in the conjunctiva, along with different levels of chemosis (swelling of the conjunctiva) and swelling of the eyelids. 
  • Vernal keratoconjunctivitis 
  • There are two main types of VKC (Vernal Keratoconjunctivitis): palpebral and limbal. In palpebral VKC, a prominent indicator is the presence of giant papillae. The giant papillae have a characteristic flattened top, often described as “cobblestone papillae.” In severe instances, these enlarged papillae can lead to mechanical ptosis, which refers to a drooping eyelid. 
  • Atopic keratoconjunctivitis 
  • AKC can have an impact on various parts of the eye, including the eyelid skin and lid margin, conjunctiva, cornea, and lens. The skin on the eyelids may display symptoms of eczematoid dermatitis, such as dryness, scaliness, and inflammation. Additionally, the lid margins can experience issues like dysfunction of the meibomian glands and keratinization. It is worth noting that staphylococcal colonization is frequently observed in the eyelid margins of individuals with AKC, which can potentially lead to blepharitis. 

Age group

Associated comorbidity

  • Asthma: Allergic conjunctivitis and asthma often go hand in hand. it can be triggered by the same allergens that cause allergic conjunctivitis. 
  • Atopic dermatitis: It is common for individuals with atopic dermatitis to also experience allergic conjunctivitis. 
  • Contact lens use: People who wear contact lenses may be more prone to developing allergic conjunctivitis. The contact lenses can trap allergens and irritants against the eye, leading to inflammation and symptoms of allergic conjunctivitis. 
  • Exposure to allergens: Individuals who live in environments with high levels of these allergens are more likely to develop the condition.

Associated activity

Acuity of presentation

  • The acuity or severity of presentation of allergic conjunctivitis can vary from mild to severe, depending on the individual and the specific triggers involved.  

Differential Diagnoses

  • Bacterial conjunctivitis 
  • Viral conjunctivitis 

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

  • Maintain low humidity: Use a dehumidifier to keep indoor humidity levels between 30% and 50%.  
  • Dust and vacuum regularly: To effectively capture allergens, it is recommended to use a damp cloth for dusting surfaces and a vacuum cleaner equipped with a HEPA filter for thorough cleaning, trapping both dust and other particles. 
  • Avoid exposure to irritants: Keep away from smoke, strong perfumes, and other potential irritants that can trigger or worsen symptoms. 
  • Rinse eyes regularly: Use saline eye drops or artificial tears to rinse your eyes and flush out any allergens that may have come into contact with them. 

  • Antihistamine eye drops are widely prescribed for the treatment of allergic conjunctivitis, which is the most prevalent form of medication for this condition, their mechanism of action involves the inhibition of histamine release, a substance that is discharged during an allergic response. This release of histamine is the primary cause of the inflammation and itching experienced in cases of allergic conjunctivitis. By effectively reducing these symptoms, antihistamine eye drops offer much-needed relief to individuals suffering from this condition. 
  • Another type of medication used for allergic conjunctivitis is mast cell stabilizers. These medications work by preventing the release of histamine and other inflammatory chemicals from mast cells, which are involved in the allergic response. Mast cell stabilizers are often used as a preventative measure to reduce the frequency and severity of allergic conjunctivitis symptoms. 
  • Corticosteroid eye drops may also be prescribed for severe cases of allergic conjunctivitis.  

 

 

  • Consultation with an Eye Care Professional: If you suspect you have allergic conjunctivitis, it’s important to consult with an eye care professional, such as an ophthalmologist or optometrist. They can diagnose your condition and determine the most appropriate treatment plan. 
  • Identification and Avoidance of Allergens: Try to identify the specific allergens that trigger your conjunctivitis symptoms.  
  • Prescribed Eye Drops: Depending on the severity of your symptoms, your eye care professional may prescribe medicated eye drops to help alleviate your allergic conjunctivitis. These eye drops often contain antihistamines, mast cell stabilizers, or corticosteroids to reduce inflammation, itchiness, and redness. 
  • Oral Antihistamines: In some cases, your eye care professional may also recommend oral antihistamines to manage systemic allergic symptoms, such as sneezing or a runny nose. 

  • Acute phase: The main goal during the acute phase is to alleviate the symptoms of allergic conjunctivitis. This phase typically involves the use of medications such as antihistamines, mast cell stabilizers, and nonsteroidal anti-inflammatory drugs (NSAIDs). 
  • Maintenance phase: Once the acute symptoms have been controlled, the management shifts to the maintenance phase. The basic  objective of this phase is to prevent the recurrence of allergic conjunctivitis and maintain symptom control. 
  • Preventative phase: In the preventative phase, measures are taken to minimize exposure to allergens and reduce the risk of developing allergic conjunctivitis. This phase focuses on identifying and avoiding triggers certain chemicals dust mites, pet dander & pollen grains. 

Medication

 

naphazoline/pheniramine 

Solution

Ophthalmic solution

up to 4 times a day

1-2 drops instilled into the affected eye



olopatadine ophthalmic 



Dose Adjustments

Indicated for itching in the eye that is associated with allergic conjunctivitis
0.1% solution- 1 drop twice daily in the affected eye at an interval of 6-8 hours
0.2% solution- Instil 1 drop in the affected eye each day
0.7% solution- Instil 1 drop in the affected eye each day

ketotifen, drug-eluting contact lens 



Dose Adjustments

The disposable lenses are packed with H1 histamine receptor antagonist
Insert 1 lens in each eye each day
Discard the lens after usage each day
Check the instruction guide

nedocromil ophthalmic 

During exposure, apply 1 to 2 drops into each eye twice daily



cenegermin 

associated with ocular itching:

Insert into the canaliculus at the lower lacrimal punctum; a single insert delivers 0.4 mg up to 30 days after insertion.
The insert is resorbable & does not require to be removed; if required, use saline irrigation or just manual expression for removing the insert.



cetirizine ophthalmic 

Put one drop in each affected eye two times a day, with an interval of approximately 8 hours



azelastine ophthalmic 


Indicated for Allergic Conjunctivitis
Apply one drop into the affected eye/eyes two times a day



levocabastine 

Spray the suspension in every eye twice daily
Increase the dose to 3-4 each day if required



pemirolast 


Indicated for Allergic Conjunctivitis
Administer one-two drops into the affected eye four times a day




antazoline 0.5% + xylometazoline HCI 0.05% as ophthalmic solution of 1 to 2 drops given into the affected eye(s) twice or thrice a day



dexbrompheniramine 

Take a dose of 2 mg in combination with pseudoephedrine up to four times a day



antazoline 

Apply 1-2 drops to affected eye(s) every 2 to 3 times a day



 

naphazoline/pheniramine 

<6 years: Not established:


>6 years: 1-2 drops instilled into the affected eye up to 4 times a day



olopatadine ophthalmic 



Dose Adjustments

Indicated for itching in the eye that is associated with allergic conjunctivitis
Safety and efficacy are not seen in pediatrics
For more than 2 years-
0.1% solution- Instil 1 drop twice daily in the affected eye at an interval of 6-8 hours
0.2% solution- Instil 1 drop in the affected eye each day
0.7% solution- Instil 1 drop in the affected eye each day

ketotifen, drug-eluting contact lens 



Dose Adjustments

The disposable lenses are packed with H1 histamine receptor antagonist
For more than 11 years
Insert 1 lens in each eye each day
Discard the lens after usage each day
Check the instruction guide

nedocromil ophthalmic 

<3 years: Safety and efficacy not established
>3 years: During exposure, apply 1 to 2 drops into each eye twice daily



cetirizine ophthalmic 

Safety and efficacy not determined in less than two years old
≥2 years:
Put one drop in each affected eye two times a day, with an interval of approximately 8 hours



azelastine ophthalmic 


Indicated for Allergic Conjunctivitis
Age >3 years
Apply one drop into the affected eye/eyes two times a day
Age <3 years
Safety and efficacy not established



levocabastine 

Spray the suspension in every eye twice daily
Increase the dose to 3-4 each day if required
Discontinue the product if no effect is seen in 3 days



pemirolast 


Indicated for Allergic Conjunctivitis
Age 3-18 years
Administer one-two drops into the affected eye four times a day
Age <3 years
Safety and efficacy not established



dexbrompheniramine 

For >6 years old:
Take a dose of 1 mg in combination with pseudoephedrine up to four times a day



 

Media Gallary

Allergic conjunctivitis

Updated : January 1, 2024




  • Allergic conjunctivitis is a prevalent ocular condition distinguished by the inflammation of the conjunctiva, a transparent membrane enveloping the front part of the eye and the inner surface of the eyelids. This condition arises when the conjunctiva is exposed to an allergen, leading to the activation of the immune system. 
  • The identification of allergic conjunctivitis typically relies on a comprehensive evaluation of the patient’s medical background and meticulous clinical examination. The onset of an allergen sets off an allergic reaction, thus, the fundamental behavioral adjustment for all forms of allergic conjunctivitis involves avoiding exposure to the triggering allergen. Apart from this, the management of allergic conjunctivitis differs to some extent based on the particular subtype. Various medications such as mast cell stabilizers, topical antihistamines corticosteroids and nonsteroidal anti-inflammatory drugs, can be employed for the treatment of allergic conjunctivitis. 
  • Simple Allergic Conjunctivitis: It is estimated that a significant number of individuals, approximately 10% to 30% of the total population, experience a common ocular allergy. In general, symptoms tend to manifest in individuals below the age of 20, while their occurrence decreases in older age groups. Although allergic conjunctivitis can manifest as a standalone condition, it is frequently linked to atopic dermatitis, allergic rhinitis, and/or asthma. 
  • Vernal Keratoconjunctivitis: This condition is more commonly found in males, with a ratio of occurrence between 2:1 and 3:1, particularly in dry and hot climates. It primarily affects individuals under the age of ten, often with a background of atopy or asthma. 
  • Atopic Keratoconjunctivitis: Typically, this condition is not observed before adolescence and reaches its peak between the age of 30 to 50 years. Atopic dermatitis is commonly observed in most cases. Like vernal keratoconjunctivitis, there is a higher prevalence among males compared to females (with a ratio lies between 2:1 and 3:1). 
  • Giant Papillary Conjunctivitis: This condition is most seen in teenagers and younger individuals, which is likely due to its temporal association with the use of contact lenses. It is primarily observed in individuals who use soft contact lenses and affects around 5% of that population.  
  • Sensitization: Initially, the individual is exposed to an allergen, such as pollen, pet dander, dust mites, or certain chemicals. These allergens are usually harmless substances, but in susceptible individuals, the immune system recognizes them as foreign and mounts an allergic response. During the first exposure, the allergen is recognized by antigen-presenting cells (APCs), which capture the allergen and present it to T-helper lymphocytes. 
  • Activation of T-helper cells: The allergen presentation by APCs activates T-helper cells, specifically type 2 T-helper cells (Th2). This leads to the release of cytokines, such as interleukin-4 (IL-4), interleukin-5 (IL-5), and interleukin-13 (IL-13). 
  • IgE pr