conjunctivitis%20-%20allergic,%20seasonal%20-and-%20perennial
CONJUNCTIVITIS - ALLERGIC, SEASONAL & PERENNIAL

Conjunctivitis is the inflammation of the conjunctiva.

Allergic conjunctivitis happens when the direct exposure of the ocular mucosal surfaces to the environment causes an immediate hypersensitivity reaction in which triggering antigens couple to reaginic antibodies (IgE) on the cell surface of mast cells and basophils, leading to the release of histamines that causes capillary dilation and increased permeability and thus conjunctival injection and swelling.
Seasonal allergic conjunctivitis is the most common form of allergic conjunctivitis in temperate climates. It usually occurs and recurs at a certain period of the year (eg summer).
Perennial allergic conjunctivitis manifests and recurs throughout the year with no seasonal predilection. It is most common in tropical climates.

Diagnosis

  • Allergic conjunctivitis are usually diagnosed by history & clinical presentation

History

  • 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
      • House dust mites, animal dander, & feathers are the major allergens implicated in PAC & AKC
    • Occupational exposure
    • Travel
    • Use of eye care products, topical medications, solutions or contact lenses

Physical Examination

  • Clinical signs are usually bilateral & vary based on patient’s age, mediating cell type & association with other conditions
  • Conjunctival chemosis, hyperemia & a predominantly papillary conjunctival reaction

Laboratory Tests

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

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, spread on slide & stain
  • Allergic response is indicated by presence of eosinophils, neutrophils &/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
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