PKC Flashcards
Define PKC
PKC is a characteristic modular affection (phlycten) occurring as an allergic response of conjunctival and corneal epithelium to some ENDOGENOUS allergens to which they have become sensitised
Other name for PKC
Microbial allergic conjunctivitis ; called so because it is believed to be a delayed hypersensitivity reaction(type 4) to endogenous microbial proteins
What are the causative proteins / allergens of PKC ?
Staphylococcus proteins - now the most common cause
Tuberculous protein - previously the most common cause
Other allergens - proteins of moraxella axenfeld bacillus and certain parasites ( such as worm infestations )
PKC is more common in whom
Girls are more commonly affected than boys
While in VKC boys are most commonly affected
Pathology / stages of PKC
Stage of nodule formation - occurs due to exudation and infiltration of leukocytes into the layers of conjunctiva leading to nodule formation ; in the nodules the Central cells are neutrophils and peripheral cells are lymphocytes
Stage of ulceration - necrosis at the apex of nodule forming ulcer
Stage of granulation - floor of the ulcer covered by granulation tissue
Stage of healing - occurs with minimal scarring
Is PKC unilateral or bilateral condition ?
Usually UNILATERAL unlike VKC which is usually bilateral
Signs of PKC
Simple PKC
Nodular PKC
Miliary PKC
Features of simple PKC
Most common variety
Here there will be mostly one or rarely to pinkish white nodules usually around the limbus surrounded by hyperaemia of the bulbar conjunctiva ; rest of the conjunctiva is normal
Features of necrotising PKC
Presence of very large phlycten with ulceration and necrosis leading to pustular conjunctivitis
Miliary PKC
Multiple phlycten are arranged haphazardly or in the form of a ring around the limbus forming ring ulcer
Phlyctenular keratitis types
Ulcerative
Diffuse infiltrative
Dd of PKC
Episcleritis
Scleritis
Conjunctival foreign body granuloma
Investigations of PKC
Done in recurrent cases
For ruling out tuberculous and parasitic infections
For ruling out tuberculous infection - chest x ray , TLC , DLC ,ESR,mantoux test
For ruling out parasitic infection - stool examination for cyst and ova
Treatment of PKC
Local therapy - topical steroids , topical antibiotic (for secondary infection) , atropine 1% ointment for corneal involvement
Specific therapy - ATT (for tuberculous focus) , surgical removal or systemic antibiotic for septic focus , complete eradication if parasitic infestation is found
General measures - improve hygiene , supplement vit a, c , d
