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

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

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

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

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

13. Predisposing factors

14. Lagophthalmos

15. Trichiasis

16. Y DRY EYE CONTACT LENS USE TRAUMA KERATOMALACIA

17. Symptoms of bacterial keratitis

18. Photophobia Lacrimation Diminution of vision

19. Signs

20. Blepharospasm

21. Discharge

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

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

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

25. Desquamated tissue adheres to ulcer floor

26. Epithelium regenerates

27. Stages of bacterial ulcer

29. Progressive stage

30. Infiltration by leucocytes

31. 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.

33. 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

35. Regressive stage

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

37. dissolve the necrotic tissues

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

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

41. Cicatrization

42. 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

44. Summary of stages of bacterial ulcer

45. Progressive stage Regressive stage Vascularization and scaring

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

47. Complications

48. 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

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