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Ferdous bacterial keratitis copy

Review on Bacterial Keratitis

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Ferdous bacterial keratitis copy

  1. 1. Dr Md Ferdous Islam
  2. 2. Introduction • Bacterial keratitis usually develops when ocular defens have been compromised. •Host cellular and immunologic responses to offending agent which may be bacterial, viral, fungal or protozoal organisms leads to formation of ulcer. •Sight threatening condition and should be considered as ocular emergency.
  3. 3. Barriers Of Microbial Infection • Bony orbital rim,eyelids, • Intact corneal & conjunctival epithelium Anatomical • Tear film-mucus layer • Lacrimal systemMechanical • Tear film constitutes-IgA, complement components, and enzymes lysozyme, lactoferrin, betalysins • CALT Antimicrobial
  4. 4. Risk Factors • 1. TRAUMA -breach in corneal epithelium -refractive surgery -agricultural injury -inoculation of organism • 2. OCULAR SURFACE DISEASES - blepharitis, ectropion, entropion, trichiasis, lagophthalmos, chronic dacryocystitis • 3.CONTACT LENS WEAR • 4. LOCAL IMMUNE SUPPRESSION DUE TO TOPICAL CORTICOSTEROIDS
  5. 5. Systemic Factors 1.Malnutrition 2.Diabetes 3.Immunosupression-Systemic steroids, AIDS 4.Chronic alcoholism
  6. 6. Aetiology • Caused by organisms which produce toxins causing tissue death i.e. necrosis characterized by pus formation. • Such purulent keratitis is usually exogenous due to infection by pyogenic bacteria such as -Pseudomonas, -Staphylococcus, -Streptococcus, -N. gonorrhoeae and -C. diphtheriae
  7. 7. Aetiology • Most of the bacteria are capable of producing corneal ulcer only when the epithelium is damaged. • N. gonorrhoeae, C. diphtheriae, Haemophilus , N. meningitidis can penetrate intact corneal epithelium.
  8. 8. Pathogenesis Corneal abrasion Microbes adhere to epithelium, cloning ,invasion to stromal lamellae,release toxins & lytic enzymes Host response PMNs at the site of ulcer from tears & limbal vessels release of cytokines & interleukins  progressive invasion of cornea & increase in size of ulcer Phagocytosis Release of free radicals, proteolytic enymes Necrosis & sloughing of epithelium, Bowman’s membrane & stroma A saucer shaped defect with projecting walls above the normal surface due to swelling of tissue resulting from fluid imbibition by corneal stroma with grey zone of infiltration
  9. 9. Presentation 1. Diminution of vision, depending on location of corneal ulcer 2. Watering due to reflex lacrimation 3. Photophobia 4. Pain due to exposed nerve endings 5. Mucopurulent / purulent discharge
  10. 10. Ocular Examination 1.Visual acuity-reduced 2.Slit lamp Biomicroscope Lids - edema Conjunctiva – Ciliary congestion
  11. 11. 4. Cornea -Location of the ulcer- central, paracentral peripheral,total. -Size , shape, depth, margins & floor- depends on stage of ulcer. -Density and extent of stromal infiltration. 5. Anterior chamber - Cells/flare, mobile Hypopyon.
  12. 12. Iris- muddy Toxin induced iritis Pupil – miotic Other: -Sac syringing -corneal sensation -Fluorescein staining
  13. 13. Special Features 1.Staphylococcal • Central,oval, opaque • Distinct margins. • Mild oedema of remaining cornea. • Stromal abscess in longstanding cases. • Mild to moderate AC reaction. • Affects compromised corneas e.g. Bullous keratopathy , dry eyes , atopic diseases.
  14. 14. 2.Pneumococcal • Ulcer serpens is greyish white or yellowish disc shaped ulcer occuring near center of cornea. • starts at periphery & spreads towards centre • Tendency to creep over the cornea in serpiginous fashion- Ulcus Serpen. • Violent iridocyclitis is often associated with it. • Hypopyon – always present • It has great tendency for PERFORATION.
  15. 15. 3. Pseudomonas • Rapidly spreading. • Extends periphery & deep within 24 hrs. • Stromal necrosis with shaggy surface • Spreads concentrically and symmetrically to involve whole depth of cornea-Ring ulcer. • Greenish-yellow discharge. • Hypopyon is present. • Untreated  corneal melting.
  16. 16. 4. Streptococcus viridans • Infectious crystalline keratopathytype of stromal keratitis. • Crystalline arborifoem (needle like) white opacities in stroma , not associated with infiltration & ocular inflammation • Due to proliferation of bacteria between the stromal lamellae.
  17. 17. Complications Of Corneal Ulcer 1. Spread of ulcer horizontally and depth-wise, leading to thinning of cornea 2. Descemetocele 3. Perforation of ulcer – sudden exertion such as coughing, sneezing, straining at stool or firm closure of eyes increase in intra-ocular pressure (IOP) perforation a) Peripheral perforation -iris prolapse through opening. Exudation takes place on prolapsed tissue an  adherent leucoma .
  18. 18. b) Central perforation  anterior chamber collapse  lens comes in contact with corneal endothelial surface  anterior capsular cataract  repeated healing and perforation leading to corneal fistula formation c) Sloughing of whole cornea: prolapse of iris  pupillary block and exudation on iris  pseudocornea  anterior synechiae  angle of anterior chamber is occluded leading to secondary glaucoma  anterior staphyloma . d) Intra-ocular purulent infection: due to perforation bacteria enter in the eye and causes endophthalmitis / panophthalmitis
  19. 19. Investigations Specific – Corneal scraping Gram stain, Culture & Antibiotic sensitivity Culture of contact lens & solution Conjunctival Swab
  20. 20. Gen Consideration • Hospitalization • Discontinuation of contact lens wear • Eye shield
  21. 21. LOCAL TREATMENT Control of infection with appropriate antibiotic(s) a. based on clinical judgment b. based on finding of smear examination c. based on culture and sensitivity report • Antibiotic Monotherapy -fluroquinolone -Ciprofloxacin or Ofloxacin -New generation fluroquinolone
  22. 22. •Antibiotic duotherapy •Subconjunctival antibiotics •Mydriatics •Steroids
  23. 23. Systemic Antibiotics Indications • Severe keratitis • Scleral involvement • Hypopyon • Impending perforation • Frank perforation with risk of intraocular spread • Infection in children • P. aeruginosa infection • N. meningitidis infection • H. influenzae • N. gonorrhoeae infection
  24. 24. Adjuvant Therapy 1.Cycloplegic : Atropine 1% or cyclopentolate 1% or Homatropine 2%- prevents ciliary spasm, relieves pain, breaks adhesions and prevent synechia formation. 2.Analgesic anti-inflammatory 3. Oral vitamin C 4. Acetazolamide Tab - impending perforation or perforated corneal ulcer and in cases where there is raised IOP
  25. 25. Treatment Of Impending Perforation 1. Straining should be avoided. 2. Pressure bandage 3. Lowering of IOP 4. Tissue adhesive glue (cynoacrylate) 5. Conjunctival flap 6. Soft contact lens Bandage 7. Penetrating keratoplasty
  26. 26. Treatment Of Perforated Corneal Ulcer • Tissue adhesives • Conjunctival flap • Soft bandage • Keratoplasty
  27. 27. • Modification of initial antimicrobial therapy: -Should be based on clinical response not on culture sensitivity • If pt is responding  no change in initial treatment • If pt is not responding/ worsening drugs are changed according to antimicrobial sensitivity
  28. 28. • SIGNS OF HEALING :  -resolution of lid edema, congestion  -decreased density of stromal infiltrate  -reduction of corneal oedema  -reduction in AC reaction/hypopyon  -re-epithelization  -corneal vascularization • Antibiotic frequency-tapered to 4hrly after 72 hrs
  29. 29. • SIGNS OF NON-RESPONSE - Increase in infiltration, epithelial defect, height of hypopyon, Corneal thinning, perforation Treatment • Re-evaluate for Drug toxicity,Non-infectious causes or Unusual organisms • Modification of anti-microbial therapy according to antimicrobial sensitivity • Scraping of ulcer floor followed by cauterization with pure (100%) carbolic acid or 10-20% trichloracetic acid. • Therapeutic keratoplasty
  30. 30. Topical Corticosteroids • Controversial in bacterial keratitis • The rationale for using steroids - to decrease tissue destruction. CRITERIA FOR TOPICAL STEROIDS IN ULCER -- 1.Must not be used in presence of active infected corneal ulcer 2.If bacteria shows in-vitro sensitivity to the antibiotic being used 3.Patients compliance for follow-up 4. No other virulent organism is found
  31. 31. Surgical Treatment • 1.Tissue adhesive-Cyanoacrylate glue- small perforations< 3mm - descemetocele • 2. Patch graft –perforation- 5mm in diameter • 3 . Therapeutic keratoplasty -large areas of perforation, necrosis -Non-healing ulcer

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