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Bacteriology of Corneal ulcer (Etiology (Causative organism (Gram + Cocci…
Bacteriology of Corneal ulcer
Etiology
Corneal epithelial damage
Corneal abrasion due to foreign body / Misdirected cilia / Trivial trauma in contact lens wearers
Xerosis
Keratomalacia (Necrosis of epithelium)
Bulluous keratopathy ➡️Corneal Edema ➡️Desquamation
Tropic changes in Neuroparalytuc keratitis
Sources of infection
Exogenous
Conjunctival / Lacrimal sac
infected forien bodies / Vegetative material
From ocular tissue
Conjunctive
Sclera
Uveal tract
Causative organism
Gram + Cocci
Staph aureus (COMMON)
Strep pneumococcus (COMMON)
Staph epidermidis
Gram +bacilli
C Diphtheria
C Xerosis
Bacilus cereus
P acne
Clostridium
Gram - Cocci
Neisseria Gonorrhoeae
& Meningitidis ( Common )
Gram -bacilli
P Aeruginosa (COMMON)
Enterobacteriaceae (COMMON)
Moraxella lacunata (DIPLOBACILLUS)
H Influenzae ( COCCIBACILLUS) :
Gram+ filamentous
Actinomycetes , Nocardia
Mycobacterium
Pathogenesis
Of Localised ulcer
Stage of Progressive infilteration of Polymorphonuclear cells into epithelium
➡️Necrosis
Stage of active ulceration
Due to necrosis & sloughing of epithelium , Bowman membrane , storms of cornea
Floor & margin of ulcer shows GREY INFILTERATION & SLOUGHING due to imbibition of fluid & leucocytes
Surrounding Hyperaemia
Purulent Exudates
Vascular congestion of iris & Ciliary body
Diffuse superficial ulceration
Descematocele formation & impending perforation
Stage of regression
Cellular & Humoral immune response
Phagocytosis of offending organism & necrotic Cellular debris
Neovascularization
Healing
Stage of Cicatrization
Progressive epithelization
Fibrosis by corneal fibroblasts & thickening of stroma
Scarring
Nebula ( Bowman membrane & superficial stroma )
Macula ( 1/3 of stroma )
Leucoma ( > 1/3 of stroma )
Of perforated ulcer
Descematocoele formation
Perforation due to straining by Coughing / sneezing /.Stool strain
Aqueous escapes
⬇️ IOP
Plugging by iris ➡️ Cicatrization ➡️ Adherent leucoma
Of Sloughing Corneal ulcer
Sloughing of cornea
Prolapse & inflammation of iris
False cornea develops
Pseudocirnea develoos due to fibrosis & corneal epithelization
Bulges forward due IOP
Ecstatic Cicatrix
Anterior staphyloma ( Bunch of Black rapes)
Clinical features
Symptoms
Pain & foreign body sensation
Watering from eye
Photophobia
Redness of eye 👁 due to congestion
Sign
Swelling of lids
Blepharospasm
Chemosis of conjunctiva
Characteristic Corneal ulcer
Oval yellowish white ulcer
Swollen margins
Necrotic material at floor of ulcer
Surrounding stroma edema
Yellowish white opaque ulcer with surrounding clear cornea ( Staph aureus & Strep Pneumoniae
Greenish mucopurulent exudate & liquefaction necrosis with surrounding ground glass cornea ( P Aeruginosa )
Shallow greyish white ulcer with stroma opalescent & ring shaped corneal infilterate ( Enterobacteriacae )
Muddy iris
⬆️ IOP