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Three Coats of Eye Ball

Three Coats of Eye Ball. 1.OUTER COAT 2.MIDDLE COAT 3.INNER COAT. Outer Coat. Tough Fibrous Coat Post 5/6 th of Globe White & Opaque Sclera Radius---12mm. Outer Coat. Tough Fibrous Coat Ant 1/6th of Globe Transparent Cornea Radius---8mm. Corneoscleral Limbus.

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Three Coats of Eye Ball

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  1. Three Coats of Eye Ball 1.OUTER COAT 2.MIDDLE COAT 3.INNER COAT

  2. Outer Coat Tough Fibrous Coat Post 5/6th of Globe White & Opaque Sclera Radius---12mm

  3. Outer Coat Tough Fibrous Coat Ant 1/6th of Globe Transparent Cornea Radius---8mm

  4. Corneoscleral Limbus Junction of Cornea and Sclera Contains 1.Trabecular Meshwork 2.Canal of Schlemn

  5. Size of Cornea Verticle-------10.6 mm Horizontal---11.7 mm Thickness Central portion----0.52 mm Peripheral portion----1 mm

  6. Structure Three Layers 1. Epithelium & its Basement 2. Stroma & its ant condensation ( Bowman Zone) 3.Endothelium & its Basement (Descemet Membrane)

  7. Structure From Anterior to Posterior 1. Epithelium 2. Bowman Zone 3. Stroma 4. Descemet Membrane 5. Endothelium

  8. Epithelium • 50-60 µm thick • Covers the stroma anteriorly • Continuous with epithelium of conjunctiva • Life of epithelial cells is 7 days • Prevent aqueous solutions to penetrate

  9. Epithelium • Surface cell layer • Wing cell layer • Basal cell layer • Basement membrane

  10. Stroma 90% of the corneal thickness • Bowman Zone • Lamellar Stroma Once deformed its typical structure is not restored

  11. Inner Lining • Descemet membrane (Regenerates) • Endothelium Single layer of cells Cells are tightly bound together Responsible for dehydration Never regenerates

  12. Blood supply • Central cornea is avascular • Corneoscleral limbus is generously supplied by anterior conjuntival branches of the anterior ciliary arteries • Aqueous humor and tear film provides nutrients

  13. Nerve Supply • Branches of the ophthalmic division of trigeminal nerve and are solely sensory • Most are concentrated in the anterior stroma beneath the Bowman zone and send branches forward into epithelium • Descemet membrane and endothelium are not innervated

  14. Cornea • The microvilli of the anterior surface of the squamous cell layer are wet by the mucin of tear film • These cells are joined by tight junctions that exclude water soluble substances

  15. Transparency • Tight junctions of the epithelial cells • Endothelial pump mechanism • Absence of blood vessels • Absence of pigments • Scarcity of cell nuclei in stroma • Regular structure of stroma

  16. Signs of Corneal Disease Superficial 1.Punctate epithelial erosions Tiny ,slightly depressed, epithelial defects which stain with flourescein but not with rose Bengal PEE are non specific and may develop in a wide variety of keratopathies

  17. Signs of Corneal Disease Superficial 2.Punctate epithelial keratitis It is the hallmark of viral infections. • Swollen epithelial cells • Visible unstained • Stains with rose bengal

  18. Signs of Corneal Disease Superficial 3.Epithelial Oedema Sign of • Endothelial decompensation • Severe acute elevation of IOP

  19. Signs of Corneal Disease Superficial 4.Filaments Small coma shaped mucus strands lined with epithelium. One end attached with epithelium

  20. Signs of Corneal Disease Superficial 5.Pannus Inflammatory or degenerative ingrowth of fibro vascular tissue from limbus

  21. Signs of Corneal Disease Stromal Lesions 1.Infiltrates Focal areas of active stromal inflammation 2. Oedema Increased corneal thickness Decreased transparency 3. Vascularization

  22. Signs of Corneal Disease Lesions of Descemet Membrane • Breaks Corneal enlargement Keratoconus Birth trauma 2. Folds (Striate Keratopathy) Surgical trauma Ocular hypotony Stromal oedema

  23. PRINCIPLES OF MANAGEMENT OF CORNEAL DISEASE • Control of infection • Control of inflammation • Promotion of re-epithelialization – lubrication – lid closure – bandage soft contact lens • Prevention of perforation – tissue adhesive glue – conjunctival flap – systemic immunosuppressive agents • Corneal grafting

  24. MICROBIAL KERATITIS( Bacterial) • Ocular surface disease: Trauma, post-herpetic corneal disease, bullous keratopathy, corneal exposure, dry eye and diminished corneal sensation. • Contact lens wear

  25. MICROBIAL KERATITIS( Bacterial) Pathogens which can produce corneal infection in intact epithelium. • 1.Neisseria gonorrhoeae • 2.Corynebacterium diphtheriae • 3.Listeria • 4.Haemophilus

  26. Staph. aureus and strep. pneumoniae • Oval, yellow-white, densely opaque stromal suppuration surrounded by relatively clear cornea

  27. Psuedomonas • Thick mucopurulent exudate, diffuse liquefactive necrosis and semi-opaque ground glass appearance of adjacent stroma

  28. Enterobacteriaceae • Shallow ulceration, grey-white pleomorphic suppuration and diffuse stromal opalescence. Endotoxins may induce ring-shaped corneal infilterates

  29. MANAGEMENT • History • Clinical examination (including staining and sensitivity) • Hospitalization • Corneal scrapping • Treatment

  30. Treatment • Topical antibiotics – combination therapy with fortified amino glycoside and fortified cephalosporin or monotherapy with fluoroquinolone. Initial instillation at hourly intervals. • Subconjunctival injections • Systemic ciprofloxacin 750mg BD

  31. Cycloplegics • Steroid therapy (controversial) • Corneal biopsy or excisional keratoplasty

  32. Poor response to treatment • Wrong diagnosis • Wrong treatment • Drug toxicity

  33. FUNGAL KERATITIS • Filamentous fungal keratitis –Aspergillus - Fusarium

  34. History of vegetable matter injury • Greyish-white ulcer with indistinct margins • Surrounded by feathery infilterates • Ring infilterate • Endothelial plaque • Hypopyon

  35. Candida keratitis • Usually develops in pre-existing corneal disease or immunocompromised patient • Yellow-white ulcer • Dense suppuration

  36. D/D of fungal keratitis • Suppurative bacterial keratitis • Herpetic stromal necrotic keratitis

  37. MANAGEMENT • Culture • Biopsy • Antifungal therapy – Initially broad-spectrum econazole 1% topically – Then depending upon sensitivity natamycin or imidazole for 6 weeks • Systemic ketoconazole • Therapeutic penetrating keratoplasty

  38. ACANTHAMOEBA KERATITIS • Protozoan –active (trophozoite) –dormant (cystic) • Common in swimmers and CL wearers

  39. CLINICAL FEATURES • Blurred vision and disproportionate pain • Patchy anterior stromal infilterates • Perineural infilterates (radial keratoneuritis) • Infilterates coalesce –ring abcess, ulceration and hypopyon • White satellite lesions

  40. MANAGEMENT • Corneal scrappings stained with calcoflour white • Corneal biopsy • Treatment with chlorhexidine, polyhexamethylenebiguanide drops, dipropamidine and propamidine. • Therapeutic penetrating keratoplasty

  41. HERPES SIMPLEX KERATITIS Primary ocular herpes: - Blepharoconjunctivitis - Keatitis (punctate epithelial)

  42. DENDRITIC ULCER • Opaque cells arranged in a course punctate or stellate pattern • Central desquamation leads to a linear branching ulcer. –Fluorescein stain – Rose Bengal stain –Diminished corneal sensitivity • Anterior stromal infilterates • Geographical or amoeboid ulcer

  43. Differential diagnosis • Herpes zoster keratitis • Healing corneal abrasion • Pseudodendrites due to soft contact lens • Acanthamoeba keratitis • Drug toxicity

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