Immunopathogenesis of ocular allergy: a schematic approach to different clinical entities

Abstract

A review of the recent literature allows us to better understand the mechanisms involved in the development of ocular allergy and to guide us toward a more schematic approach, which could possibly be useful in forming a new classification, standardizing clinical phases and individuating new treatment targets.

Cellular changes in tears associated with keratoconjunctival responses induced by nasal allergy

“…These links allow the nasal allergic reaction to affect the conjunctiva in various ways upon the involvment of various mechanisms. [3][4][5][7][8][9][10][12][13][14][15][16][17][18][19][20][21][22][29][30][31]37 Diagnostic confirmation of hypersensitivity mechanism(s) underlying the allergic keratoconjunctivitis consists usually of (1) an ophthalmologic examination, evaluation of the cornea by slit-lamp vital staining with fluorescein, and cytologic examination of the conjunctiva using brush, impression, or scraping techniques; (2) determination of specific Keratoconjunctival response-cytologic changes in tears Z Pelikan…”

“…[3][4][5][6][7][8][9][10][12][13][14][15][16][18][19][20][21][22]25,[33][34][35][36] The conjunctiva has manifold anatomic and functional relationships with nasal mucosa, such as connection through the naso-lacrimal duct, facilitating the tear drainage into nasal cavity, and links through the blood vessel, lymphatic, and neurogenic network. These links allow the nasal allergic reaction to affect the conjunctiva in various ways upon the involvment of various mechanisms.…”

“…13,[16][17][18][19][20][21][22]28,34 These techniques generate data concerning the cellular aspects of allergy mechanism(s) in the epithelial and sub-epithelial layers. However, their disadvantages, except the brush method, are the use of anesthetics, some traumatizing effects of the ocular tissues, and stimulation of the neurogenic receptors causing undesirable reflexes.…”

“…These tests, performed on a certain organ, may definitely (1) confirm the existence of an allergic component in the particular and/or related organ(s); (2) demonstrate that a certain allergen causes indeed a certain response type in the particular organ, which can be measured quantitatively in its dynamic course; (3) to confirm the causal role of an allergic reaction occurring initially in one organ, in the secondarily induced response of another organ 7,9,10,26,[38][39][40][41] The conjunctival provocation tests with allergens are a suitable technique to demonstrate the primary conjunctival/keratoconjunctival responses resulting from direct exposure of the ocular tissue to an external allergen. 4,11,16,17,20,25,33,35,36,38,[42][43][44] However, they are unable to detect conjunctival/keratoconjunctival responses induced secondarily by an allergic reaction occurring initially in the nasal mucosa. These responses can only be detected by the NPT with allergens, in combination with registration of ocular features.…”

“…3,4,[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][28][29][30][31]34,37,43,44 This is also an exfoliative process leading to release of various cells into the particular media, such as tears or nasal secretions. [1][2][3][4][5][6][7][8][9][10][11]13,[16][17][18][19][20][21][22]25,26,[28][29][30]34,…”