Conjunctivitis%20-%20allergic,%20seasonal%20-and-%20perennial Diagnosis

• Allergic conjunctivitis are usually diagnosed by history and clinical presentation

• Personal or family history of other allergic conditions (eg atopic dermatitis, allergic rhinitis, asthma)

Determine Possible Trigger Factors

• Review history with regards to:
  • History of exposure to allergens
  • Occupational exposure
  • Travel
  • Use of eye care products, topical medications, solutions or contact lenses

• Clinical signs are usually bilateral and vary based on patient’s age, mediating cell type and association with other conditions
• Conjunctival chemosis, hyperemia and a predominantly papillary conjunctival reaction
• Slit-lamp biomicroscopy may be done to confirm or rule out diagnosis and exclude complications from other forms of ocular allergies

• Rarely needed to make diagnosis of SAC or PAC 
• Usually done for academic or confirmatory purposes

Allergy Skin Testing

• Skin prick testing and pollen IgE determination help to identify specific target allergens for immunosuppression
• May consider serum specific IgE measurement if skin testing is not advised (eg patients on antihistamine) or contraindicated or results are inconclusive (eg presence of dermatographism)

Conjunctival Allergen Challenge

• Also known as conjunctival allergen provocation test (CAPT)
• A procedure wherein the conjunctiva is subjected to undergo exposure to increasing levels of a particular antigen (to which the patient previously had a positive skin test) until an ocular reaction is observed
• For determination of ocular hypersensitivity conditions that are IgE-mediated
• Usually used in studies
• Indications:
  • For allergen identification
  • To evaluate inconsistency between history and allergen sensitization
  • To gauge the effectiveness of immunotherapy prior to allergy season
  • To evaluate drug therapies
• Contraindications:
  • Performed within the pollen season
  • Medication that can affect allergen response
  • Other ocular disorders
  • Ocular surgery in the past 6 months
  • Uses contact lens
  • Pregnant and lactating women
  • Uncontrolled and severe systemic diseases-
  • Allergy to medications used during or after CAPT
  • Ocular disorders that are non-IgE-mediated
• Primary results: Ocular pruritus (evaluated by the patient) and erythema (evaluated by the physician)
• Secondary results (which are not always present in a positive CAPT): Lacrimation, eyelid edema and conjunctival chemosis

Conjunctival Scrapings

• If positive for eosinophils it is strongly suggestive of allergy
• Negative scraping is inconclusive

Cytological Exam of Tear Fluid

• Collect tear sample with capillary tube, then spread on slide and stain
• Allergic response is indicated by presence of eosinophils, neutrophils and/or lymphocytes
  • Tear histamine or tryptase levels can also be measured

Immunoassay Testing of Tear Fluid

• Measure mast cell’s activity by determining the level of tryptase using immunoassay testing
• IgE measured in tears may be used in diagnosing allergic conjunctivitis and in evaluating its severity