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6 layers of cornea Response of cornea to injury Abrasion vs ulcer Corneal opacity- grades

Re-cap of last class. 6 layers of cornea Response of cornea to injury Abrasion vs ulcer Corneal opacity- grades Corneal transparency- causes. Keratitis - Bacterial. Dr. Soujanya K MBBS, MS, DNB, FPRS Assistant Professor YMCH. Specific learning objectives.

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6 layers of cornea Response of cornea to injury Abrasion vs ulcer Corneal opacity- grades

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  1. Re-cap of last class • 6 layers of cornea • Response of cornea to injury • Abrasion vs ulcer • Corneal opacity- grades • Corneal transparency- causes

  2. Keratitis- Bacterial Dr. Soujanya K MBBS, MS, DNB, FPRS Assistant Professor YMCH

  3. Specific learning objectives • Classification of keratitis • Predisposing factors for bacterial keratitis • Clinical features • Stages of bacterial keratitis • Complications ans sequel of bacterial keratitis • Management of bacterial keratitis

  4. Keratitis Classification: • Based on location: • Superficial • Deep

  5. Keratitis Classification: • Based on Aetiology: • Infectious • Non- infectious • immune-mediated • degenerative • neoplastic • traumatic (including chemical and thermal injuries).

  6. Infections affecting cornea

  7. Aetiological agents: Keratitis

  8. Normal cornea Highly virulent organisms usually NOT present Tear film & resistance of normal tissue protects against infection

  9. Bacteria causing keratitis • Organisms which invade de-epithelised or injured cornea- • Staphylococci • Pneumococci • Enterobacteriaceae • Atypical mycobacteria

  10. Bacteria causing keratitis • Organisms which invade intact cornea- • Gonococci • Diphtheria bacilli

  11. Predisposing factors

  12. Lagophthalmos

  13. Trichiasis

  14. Y DRY EYE CONTACT LENS USE TRAUMA KERATOMALACIA

  15. Symptoms of bacterial keratitis

  16. Photophobia Lacrimation Diminution of vision

  17. Signs

  18. Blepharospasm

  19. Discharge

  20. Circum corneal congestion Corneal Infiltration + saucer shaped ulcer Hypopyon

  21. Suppurativekeratitis • Due to organisms that produce toxins which cause tissue death (necrosis) and pus formation in the corneal tissue. • Nearly always exogenous

  22. localized necrosis of the anterior layers of the cornea Epithelium desquamates & Bowman’s membrane -damaged

  23. Desquamated tissue adheres to ulcer floor

  24. Epithelium regenerates

  25. Stages of bacterial ulcer

  26. Progressive stage

  27. Infiltration by leucocytes

  28. Progressive stage Walls: project above the normal surface of the cornea owing to swelling caused by the fluid imbibed by the corneal lamellae. Surrounding area is packed with leucocytes and appears as a greyzone of infiltration.

  29. Some of the toxins produced by the bacteria diffuse through the cornea into the anterior chamber Exert an irritative effect upon the vessels of the iris and ciliary body resulting in keratouveitis. If the irritation is great, leucocytosis takes place, and polymorphonuclear cells poured out by the vessels pass into the aqueous and gravitate to the bottom of the AC & form hypopyon

  30. Regressive stage

  31. Regressive stage Line of demarcation forms : wall of polymorphonuclear leucocytes

  32. dissolve the necrotic tissues

  33. Surrounding infiltration & swelling disappear, floor and edges become more smooth and transparent

  34. vascularization • Restore the loss of substance • Supply antibodies • Play an important role in resolving bacterial infections

  35. Cicatrization

  36. The healing of a corneal ulcer Cicatrization: Regeneration of collagen and the formation of fibrous tissue. The newly formed fibres are not arranged regularly, hence they refract the light irregularly and the scar is therefore opaque

  37. Summary of stages of bacterial ulcer

  38. Progressive stage Regressive stage Vascularization and scaring

  39. Quick revision • Classification of keratitis • Predisposing factors for bacterial keratitis • Clinical features • Stages of bacterial keratitis

  40. Complications

  41. Ectatic cicatrix Marked thinning of the entire cornea at the site of the ulcer so that it bulges under the influence of the normal intraocular pressure secondary keratectasia

  42. Some ulcers extend rapidly in depth uptoDescemet's membrane

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