Phlycten is due to -
Phlyctenular conjunctivitis - Endogenous allergy It is believed to be a delayed hypersensitivity (Type IV cell mediated) response to endogenous microbial proteins. Causative allergens are :- (i) Staphylococcus proteins (most common); (ii) Tuberculous proteins and (iii) Proteins of Moraxells axenfeld bacillus and ceain parasistes. Vernal keratoconjunctivitis - Exogneous allergy Reference : AK khurana 7th edition
Exogenous allergy
Endogeneous allergy
Viral keratitis
Fungal keratitis
Conjunctiva