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NORMAL CORNEA HISTOLOGY 1 2 3 1 4 5 epithelium 5 cells Stratified Non-keratinising Bowmans-12 microns thick Non-secretory STROMA keratocytes ARTEFACTUAL CLEFTS Endothelial cells Descemet’s CORNEAL REACTION PATTERNS Atrophy and Oedema Epithelial hyperplasia Bullous lifting Excessive intraepithelial basement membrane Band keratopathy Dystrophic calcification Epithelial hyperplasia Breaks in Bowman’s Stromal thinning Neutrophils in stroma. Acute keratitis Chronic inflammationchronic keratitis Blood vessels Plasma cells Foamy macrophages lipid keratopathy Infective agent-bacteria protozoa Dystrophic deposits Dystrophic deposits Dystrophic deposits GUTTAE Endothelial Cell Loss Ruptured Descemet’s Host-donor interface scar Corneal pathology Case 1 Acute inflammation Bacterial coloniesGram + cocci Diagnosis ? Bacterial acute keratitis Predisposing factors: adnexal infection, entropion, exposure, dry eyes, contact lens, bullous keratopathy, trauma etc G + cocci-s aureus, S. epidermidis, S pneumoniae, S pyogenes, S viridans G – cocci-N gonorrhoeae, M meningitidis G + bacilli-C Diphtheriae, diphtheroids G- bacilli- Moraxella, Acinebacter, E-coli, K pneumoniae, proteus, psuedomanas G+ filamentous bacteria Case 2 History Topical steroids after PK. Drop in vision………………. Gram + cocci without inflammation INFECTIOUS CRYSTALLINE KERATOPATHY Elaboration of biofilm by bacteria-protects them from immune system-therefore no inflammation, but also means poor response to antibiotics. Commonest bugs-strep viridans and staph epidermidis Aso can be caused by fungi and protozoa. CASE 3 Fungal hyphafilamentous branching septate spores Fungal keratitis Penetrate Descemet’s without any problem Common causes of fungal keratitis Trauma with organic material Humid warm conditions Exogenous or endogenous(immunocompromised) Aspergillus Candida Fusarium Sabaraud’s or equivalent medium for culturing Immunocompromised, steroids CASE 4 cyst Trophozoite DIAGNOSIS ? AMOEBIC KERATITIS Amoebic keratitis-cysts and trophozoites-little inflammation Loss of keratocytes PERIODIC ACID SCHIFF (PAS) + GIEMSA + Can use immunohistochemistry Differential: Acanthamoeba, Hartmannella Vahlkampfia, Naegleria Amoeba 10-50 microns Replicate by binary fission Exist as trophozoites and cysts Trophozoites are active, infectious and feed by phagocytosing. Cysts from under hostile conditions and have a double layer. Corneal epithelial trauma predisposes to infection Trophizoites attach to damaged epithelium, multiply and cause cytolysis. Migrate to stroma-elicit inflammation. Trigger keratoneuritis (inflammation follows corneal nerves). Diagnosis Culture-corneal scrapes, biopsies, keratoplasty specimens. Contact lens, cases and solutions. Non-nutrient agar inoculated and seeded with Ecoli-food source for the amoeba. Wet-mount examination of contact lens solution. Can use PAS, calcofluor white, silver stains, immunohistochemistry, EM CASE 5 Stromal thinning chronic Inflammation With giant cells. Bowman’s loss due to ulceration Chronic inflammation Scarring vascularisation Secondary lipid keratopathy Cholesterol clefts=leaky vessels DIAGNOSIS ? Herpes simplex chronic DISCIFORM keratitis HSV DNA VIRUS Type 1 usually, occasionally type 2 Diagnosis-Electron microscopy of affected cells, aspirate from blister, viral cultures, staining paraffin sections with monoclonal antibodies to HSV, PCR on corneal biopsy. HSV Primary infection-self-limiting periocular vesicles and crusting, follicular and papillary blepharconjunctivitis, punctate epithelial keratopathy. Virus lives in trigeminal ganglionreactivation Dendritic ulcer HSV Geographic ulcer Trophic keratitis Stromal infiltrative keratitis Disciform keratitis-type 4 hypersensitivity reaction-immune response to parasitized corneal stromal keratocytes-sets up vicious circle of inflammation-scarringinflammation. Complications Uveitis Glaucoma Episcleritis Scleritis Secondary bacteria infection Perforation Recurrence in corneal graft. CASE 6 Angulated Bowman’s breaks Perl’s stain shows intraepithelial iron deposits-Fleischer’s ring DIAGNOSIS ? KERATOCONUS Associations: Atopy Down’s syndrome Turner’s syndrome Marfan’s syndrome Ehlors-Danlos syndrome Aniridia Retinitis pigmentosa Ectopia Lentis Microcornea Non-specific systemic collagen abnormalities Chronic eye rubbing. Cause of prominent corneal nerves. Ruptured Descemet’s-KC Hydrops-PAS stain CASE 7 Masson’s trichrome stain-deep pink, non-birefringent hyaline bodies in anterior stroma DIAGNOSIS ? GRANULAR DYSTROPHY Masson’s trichrome positive hyaline deposits. Mutations in BIG H3 /TGF-B1 gene-encodes keratoepithelin protein. Exclude Avellino dystrophy (combined Lattice and Granular dystrophy)-by doing a Congo Red. Can recur in corneal graft-due to migration of host keratocytes into donor stroma, with elaboration of abnormal keratoepithelin CASE 8 3 DIAGNOSIS ? LATTICE DYSTROPHY Multiple, discrete, spindle shaped amyloid deposits in superficial, mid and deep stroma. Apple green birefringence of Congo red positive amyloid deposits when cross polarised Type 1,2 and 3 Mutations in BIG H3 / TGF-B1 gene Exclude Avellino by doing Masson’s trichrome stain Other amyloid stains: Thioflavine T, Immunohistochemisty using antibodies to amyloid, Sirius Red. Recurs in graft because of migration of host keratocytes into donor stromaelaboration of amyloid in donor graft. CASE 9 DIAGNOSIS? MACULAR DYSTROPHY Alcian blue positive, deposits. Present in all layers except epithelium. Deposits in keratocytes and between collagen lamellae Material is mucopolysaccharide. Can recur in graft Summary of corneal stains Lattice dystrophy-amyloid-use Congo Red / Sirius red and view under cross polarised light-apple green birefringence Granular dystrophy-hyaline material-use Masson’s trichrome Avellino dystrophy-use both Congo Red and Masson’s trichrome Macular dystrophy-mucopolysaccharide-use Alcian Blue or Hale’s colloidal iron stains or PAS Iron-use Perl’s / Prussian Blue stain- BLUE colour Calcium in band keratopathy- Alizarin Red- Red colour Basemant membranes, Descemet’s, Fungi- PAS stain- great for guttata. Bugs-Gram (bacteria), PAS (Fungi and Amoeba), Grocott silver stains for fungi. CASE 10 Epithelial bullous lifting. Thinned epithelium over bulla Epithelium loses polarity Excessive intraepithelial basement membrane-indication of chronic corneal oedema Endothelial cell loss Thickened Descemet’s-implies chronic endothelial cell loss No obvious guttata Patient had a cataract operation 1 year ago DIAGNOSIS ? Pseudoaphakic Bullous Keratopathy CASE 11 HISTORY 65 YEAR OLD MALE Recent cataract operation Early corneal decompensation. No better PK Fuch’s Endothelial Dystrophy Axial diffuse guttae or excrescences Endothelial cell loss Thickened-multilayered Descemet’s Burried guttata Can get non-guttate forms, with just very thickened Descemet’s. With chronicity, fibrous degenerative pannus formation under epithelium. CASE 12 Multilayered cellsretrocorneal surface No previous surgery or trauma Cytokeratin positive Multilayered cells DIAGNOSIS ? POSTERIOR POLYMORPHOUS DYSTROPHY Autosomal dominant, but can be recessive Circumscribed or total opacities in childhood Cells assume epithelial characteristics (stain for cytokeratin 7) Histological differential diagnosis-epithelial downgrowth, ICE syndrome, CHED (these conditions express cytokeratins) CASE 13 Ruptured and recoiled Descemet’s Shelved / sloping stroma Pauciinflammatory perforation DIAGNOSIS ? Rheumatoid Corneal melt Rheumatoid arthritis Systemic lupus erythematosis Scleroderma Churg-Strauss. Wegener’s granulomatosis Polyarteritis nodosa Giant cell arteritis Relapsing polychondritis Rosacea Dysentery Leukaemias Above are associated with peripheral corneal ulcers and melt Other causes of peripheral corneal ulceration: Marginal, Mooren’s Terrien’s. Imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteinases Enzymes released by keratocytes and epithelial cells to cause dissolution of stromal collagen.