BACTERIAL CORNEAL ULCER..

Dr. Bhushan Patil.

DEFINATION

A loss of epithelium with inflammation in the sorrounding cornea is called as corneal ulcer.

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.

NORMAL DEFENCE MECHANISM

Corneal epithelium- mechanical barrier

Conjunctiva- cellular & chemical components

Tear film- biological protective system

Major components of ocular defence system

BARRIERS OF MICROBIAL INFECTION

• Bony orbital rim,eyelids,• Intact corneal & conjunctival

epithelium

Anatomical

• Tear film-mucus layer• Lacrimal system

Mechanical

• Tear film constitutes-IgA, complement components, and enzymes lysozyme, lactoferrin, betalysins have antibacterial effect

• CALT

Antimicrobial

PREDISPOSING FACTORS OCULAR

1. Trauma-

-breach in corneal epithelium

-inoculation of organism

2.Eyelid & adnexal diseases-

- blepharitis, ectropion, entropion, trichiasis, lagophthalmos,

chronic dacryocystitis

Disturbed Tear film Recurrent epithelial erosions

3. Ocular surface disorder-

- Dry eye, Steven-Johnson syndrome, ocular burn, bullous keratopathy.

4. Contact lens use-

-Increased risk of bacterial keratitis with use of Extended soft contact lens corneal hypoxia & decompensation.

- Contamination of CL solution.

5. Local immune suppression due to topical corticosteroids.

6.Ocular surgery- cataract , LASIK.

SYSTEMIC FACTORS

1.Malnutrition

2.Diabetes

3.Immunosupression-Systemic steroids, AIDS

4.Chronic alcoholism

AETIOLOGY OF BACTERIAL ULCER

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

AETIOLOGY OF BACTERIAL ULCER

Most of the bacteria are capable of producing corneal ulcer only when the epithelium is damaged

N Gonorrhoeae, C Diphtheriae, Hemophilus , Shigella

and Listeria Monocytogenes – can penetrate intact corneal epithelium.

ORGANISM SPECIES BACTERIOLOGY

Staphylococcus S.AureusS.Epidermidis

Gram positive cocci 1.Most common organism2.Eyelid diseases3.Dry eye, bullous keratopathy, atopic disease.

Streptococcus S.PneumoniaeS. Viridans

Gram positive cocci chronic Dacryocystitis.Corneal grafts .

Pseudomonas P. Aeruginosa Gram negative bacilli

1.Contact Lens users2.Comatose pt.3.Pt on mechanical ventillator4.HIV

Moraxella M.Lacunata Gram negative diplobacilli

Malnourished, alcoholics , diabetes

Nocardia,Actinomycets

Gram positive bacilli Ocular trauma contaminated by soil

Atypical Mycobacteria

M. Chelonae Acid fast bacilli Following LASIK

PATHOGENESIS

Corneal abrasion Microbes adhere to epithelium, 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 enymesNecrosis & 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

STAGE OF PROGRESSIVE INFILTRATION

Entry and adherance of organism to breached epithelium enters into stroma.

PMNs and lymphocytes infiltrate into stroma and epithelium.

Infective organism multiplies release toxins and enzymes.

STAGE OF ACTIVE ULCERATION

Necrosis occurs due to toxins and enzymes released by infective organism.

Sloughing of epithelium and stroma ulcer.

Ulcer Borders thickening due to infiltrates and edema.

It is associated with iritis due to diffusion of toxins of infecting bacteria into AC.

Sometimes iridocyclitis is so severe that it is accompanied by outpouring of leucocytes from uveal blood vessels and these cells gravitate to bottom of the AC to form hypopyon (sterile).

STAGE OF REGRESSION

Natural host defence & antimicrobial treatment Line of demarcation forms around ulcer which contains

leucocytes which phagocytose the organism & necrotic debris Necrotic material fall off- ulcer becomes larger -> infiltration and

swelling reduce and disappears -> margin & floor becomes smooth.

Vascularization develops from limbus to corneal ulcer to restore lost tissue and to supply antibodies.

STAGE OF HEALING

Vascularization is followed by cicatrization due to regeneration of collagen and formation of fibrous tissue

Newly formed fibers are laid down irregularly, not conforming to normal pattern of stromal fibers. Therefore this fibrous tissue refracts light irregularly and forms opacity.

CLINICAL FEATURES

Clinical signs and symptoms are variable depends on the virulence of the organism duration of infection, pre-existing corneal conditions immune status of host previous use of local steroids

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

WORK-UP

Evaluation of predisposing and aggravating Factors

1. A detailed history.

2. Prior ocular history

3. Review of related medical problems, current ocular medications and history of systemic steroids.

OCULAR EXAMINATION

1.Visual acuity-reduced2.Slit lamp Biomicroscope Lids - edema

Conjunctiva – Ciliary congestion

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.

Iris- muddy

Toxin induced iritis

Pupil – miotic

Other:

-Sac syringing

-corneal sensation

-Fluorescein staining

Grading of corneal ulcer

Features Mild Moderate Severe

Size <2mm 2-5mm >5mm

Depth of ulcer

<20% 20-50% >50%

Stromal infiltrate1.Density2.Extent

DenseSuperficial

DenseUpto mid- stroma

DenseDeep stromal

Scleral involvement

present

Harrison SM. Grading corneal ulcers. Ann Ophthalmol 1975;7:537-9, 541-2.

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.

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.

BACTERIAL ULCER WITH HYPOPYON

HYPOPYON.

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.

4. Streptococcus viridans

Infectious crystalline keratopathytype 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.

Seen in following corneal grafts , prolonged use of topical steroid.

COMPLICATIONS OF CORNEAL ULCER 1. Spread of ulcer horizontally and depth-wise, leading to

thinning of cornea

2. Descemetocele – This appears as transparent vesicle surrounded by grayish zone

of infiltration.It represents condition of impending perforation of cornea

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 .

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

INVESTIGATIONS

Routine – Hemogram

BSL

HIV

Specific – Corneal scraping

Gram stain, Culture &

Antibiotic sensitivity

Culture of contact lens & solution

TREATMENT OF UNCOMPLICATED ULCER

Hospitalization

Treat the underlying cause/predisposing factor

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

Combination therapy with fortified broad spectrum antibiotics

1.Cephalosporin – gram positive cocci & some gram negative rods

Cefazolin 50mg/ml OR Ceftazidime 50mg/ml

2.Aminoglycoside - gram negative bacilli Tobramycin 14mg/ml

OR

Fluoroquinolone – broad spectrum-gram negative + gram positive

Moxiflox 5mg/ml

Topically every 30-60 min initially In severe cases- every 5 min for 30 min as a loading dose.

Vancomycin- reserved for very severe or recalcitrant infections (50mg/ml)

Amikacin (10-20mg/ml) for AF-bacilli

Fluoroquinolone monotherapy – 4th generation

< 3mm in diameter, peripheral & not associated with thinning

SYSTEMIC ANTIBIOTICS-FLUOROQUINOLONE

Indications Severe keratitis Scleral involvement hypopyon Impending perforation Frank perforation with risk of intraocular spread Infection in children P.aeruginosa infection

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 intra-ocular tension .

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

TREATMENT OF IMPENDING PERFORATION

TREATMENT OF NON HEALING ULCER Removal of any known cause.

->LOCAL

->SYSTEMIC Mechanical debridement of ulcer. Cauterisation of ulcer. Bandage soft contact lens.

TREATMENT OF PERFORATED CORNEAL ULCER

Tissue adhesives Conjunctival flap Soft bandage Keratoplasty

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

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

Signs of non-response- Increase in infiltration, epithelial defect, height of hypopyon,

Corneal thinning, perforationTreatment Re-evaluate for

Drug toxicityNon-infectious causes orUnusual 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

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

Monitor pt at 24 & 48 hrs after initiation

SURGICAL TREATMENT

1.Tissue adhesives

Cyanoacrylate glue- small perforations< 3mm

-descemetocele

2. Patch graft

-perforation –

5mm in diameter

3 . Therapeutic keratoplasty

-large areas of perforation, necrosis

-Non-healing ulcer

Thank you..