Phylcten is due to

Phlyctenular keratoconjunctivitis is a characteristic nodular affection occurring as an allergic response of the conjunctival and corneal epithelium to some endogenous allergens to which they have become sensitized. It is believed to be a delayed hypersensitivity (Type IV-cell mediated) response to endogenous microbial proteins.Causative allergens1. Tuberculous proteins were considered, previously, as the most common cause.2. Staphylococcus proteins are now thought to account for most of the cases.3. Other allergens may be proteins of Moraxella Axenfeld bacillus and ceain parasites (worm infestation). ManagementIt includes treatment of phlyctenular conjunctivitis by local therapy , investigations and specific therapy aimed at eliminating the causative allergen and general measures to improve the health of the child. Phlyctenular keratoconjunctivitis (PKC), Phlyctenular conjunctivitis, Phlyctenulosis or phlyctenular eye disease (PED) is an endogenous type IV delayed hypersensitivity (T cell-mediated) allergic reaction to an antigen. It is an inflammatory condition which causes marked photophobia and mucopurulent discharge. Ref: Khurana; 4th ed; Pg: 78