Cytologic Changes in Tears During the Late Type of Secondary Conjunctival Response Induced by Nasal Allergy

Abstract

Allergic conjunctivitis (AC),a disorder of the conjunctiva in which an allergic component plays a key role, affects approximately 15-25% of the adult and pediatric population 1-8. Estimates in the literature indicate that the seasonal allergic conjunctivitis (SAC) occurs most frequently, followed by atopic keratoconjunctivitis (AKC), vernal keratoconjunctivitis (VKC), perennial allergic conjunctivitis (PAC), whereas giant papillary conjunctivitis (GPC) occurs only sporadically 1-9. However, according to our clinical experience, the PAC occurs most frequently, followed by SAC, AKC and VKC, whereas the GPC represents only 0.51% of all AC cases 10-17. The allergic conjunctivitis (AC) can be divided into two basic forms with respect to the localization of the antigen-antibody or antigen-sensitized Th1 cell interaction with subsequent steps (allergic reaction) 10-16 In the primary form of AC, the allergic reaction due to the direct exposure of conjunctiva to an external allergen takes place primarily in the conjunctiva,. In this case, the conjunctiva is the primary site of the allergic reaction which results in the development of the primary (or classical) AC form. The secondary form of AC is induced by the allergic reaction occurring primarily in the nasal mucosa due to the exposure of nasal mucosa to an external allergen via various possible mechanisms which are described in the discussion. Moreover, the initial allergic reaction in the nasal mucosa usually can, but does not necessarily, cause also the concomitant nasal response characterized by nasal mucosal edema resulting in nasal obstruction, hypersecretion and sneezing 10, 12. Various hypersensitivity types, such as immediate type (type I, IgE-mediated), late type (type III) or delayed type (type IV, cell-mediated) can participate both in the primary and in the secondary form of AC.1, 3, 5, 6, 10-36 The involvement of various hypersensitivity mechanisms in AC may result in development of three basic types of conjunctival response (CR), an immediate (ICR), a late (LCR) or a delayed (DYCR) type, and two supplementary types of CR, such as dual late (DLCR), being a combination of an immediate and a late CR, and a dual delayed (DDYCR), a combination of an immediate and a delayed CR.1, 6, 8, 9, 10-16, 19, 20, 24, 25, 28, 3640 Additionally, the non-specific hyperreactivity resulting from direct stimulation of mucosal, glandular, or neurogenic receptors/elements in the nasal mucosa and/or conjunctival tissue by non-specific agents might also participate in the conjunctivitis complaints/response, however, usually to a lesser degree.3, 12, 41