This document discusses bacterial corneal ulcers. It begins by defining a corneal ulcer and describing the signs and symptoms which may include pain, watering, photophobia, blurred vision, redness, swelling and a well-established ulcer with an irregular yellowish-white area and overhanging margins. It then covers the etiology, noting that epithelial damage and infection can lead to ulcer formation. Common causative organisms include Staphylococcus and Pseudomonas. The pathogenesis involves stages of infiltration, active ulceration, regression and cicatrization. Clinical examination may reveal inflammation, congestion and opacity.

1. BACTERIAL CORNEAL ULCER.
PATHOGENES
IS
PATHOLOGY.
CLINICAL
FEATURES.
BY:-
DR.AYESHA SARWAR.

2. CORNEAL ULCER:-
CORNEAL ULCER MAY BE DEFINED AS A DISCONTINUATION
IN THE NORMAL EPITHELIAL SURFACE OF THE COREA
ASSOCIATED WITH NECROSIS OF THE SURROUNDING CORNEAL
TISSUE.
CHARACTERISED BY EDEMA & CELLULAR INFILTRATION.

3. BEING THE MOST ANTERIOR PART OF THE EYEBALL,
THE CORNEA IS EXPOSED TO ATMOSPHERE AND HENCE
PRONE TO GET INFECTED EASILY.
AT THE SAME TIME CORNEA IS PROTECTED FROM DAY-
TO-DAY MINOR INFECTIONS BY NORMAL DEFENCE
MECHANISMS PRESENT IN THE TEARS (Present in the
form of lysozyme and other proteins)
THERFORE, INFECTIVE BACTERIAL ULCER MAY
DEVELOP WHEN:-
Either the local defence mechanism is jeopardised.
Presence of local ocular predisposing disease.
Host’s immunity is compromised.
The causative organism is very virulent.

4. ETIOLOGY OF BACTERIAL CORNEAL ULCER:
THERE ARE 2 MAJOR FACTORS IN THE PRODUCTION OF A
PURULENT ULCER:-
A]CORNEAL
EPITHELIAL
DAMAGE
B]INFECTION
OF THE
ERODED AREA
HOWEVER, THE FOLLOWING 3
ORGANISMS CAN INVADE AN
INTACT CORNEAL EPITHELIUM
AND PRODUCE ULCERATION....
Neisseria gonorrhoea
N.meingitidis
Corynebacterium diptheriae.

5. CORNEAL EPITHELIAL DAMAGE:
PREREQUISITE TO PRODUCE CORNEAL
ULCERATION & MAY OCCUR IN THE
FOLLOWING CONDITIONS:-
1. CORNEAL ABRASION: Foriegn
body, misdirected
cilia, concretions and trivial
trauma.
2. EPITHELIAL DRYING: Xerosis &
exposure keratitis.
3. NECROSIS OF EPITHELIUM:
Keratomalacia.
4. DESQUAMATION OF EPITHELIUM: corneal
edema in bullous keratopathy.
5. EPITHELIAL DAMAGE DUE TO TROPHIC
CHANGES: Neuroparalytic keratitis.
CORNEAL
ABRASION.

7. SOURCE OF INFECTION
1] EXOGENOUS INFECTION:- Conjuctival sac, lacrimal sac, infected
foriegn bodies, water or air borne infections.
2] FROM THE OCULAR TISSUE: Owing to the direct anatomical
continuity diseases spread from...
•Conjuctiva to the corneal epithelium.
•Sclera to stroma
•Uveal tract to endothelium of cornea.
3] ENDOGENOUS INFECTION: Rare

8. CAUSATIVE ORGANISMS:
STAHYLOCOCCUS
AUREUS
PSEUDOONNAS
PYOCYANEA
STREPTOCOCCUS
PNEUMONIAE
E.COLI
PROTEUS
KLEBSIELLA
N.GONORRHOEA
N.MENINGITIDIS
C.DIPTHERIAE

9. PATHOGENESIS:
ONCE THE CORNEAL EPITHELIUM IS INVADED BY THE OFFENDING
AGENTS, THE SEQUENCE OF CHANGES OCCURING IN THE
DEVELOPMENT OF A ULCER CAN BE DESCRIBED UNDER 4 STAGES:-
1. STAGE OF INFILTRATION
2. STAGE OF ACTIVE ULCERATION
3. STAGE OF REGRESSION
4. STAGE OF CICATRIZATION.
DEPENDING UPON THE CIRCUMSTANCES, THE COURSE OF THE
BACTERIAL ULCER MAY TAKE ONE OF THE 3 FORMS:-
A. ULCER MAY HEAL & BECOME LOCALIZED.
B. PENETRATE DEEP LEADING TO CORNEAL PERFORATION.
C. SPREAD FAST IN THE WHOLE COREA AS A SLOUGHING CORNEAL
ULCER.

10. PATHOGENESIS.....

11. PATHOLOGY OF BACTERIAL
CORNEAL ULCER.....

12. 1]STAGE OF PROGRESSIVE INFILTRATION:
CHARACTERIZED BY INFILTRATION F LYMPHOCYTES INTO THE
EPITHELIUM FROM THE PERIPHERAL CIRCULATION & THE
UNDERLYING STROMA.
SUBSEQUENTLY, NECROSIS OF THE INVOLVED TISSUE MAY
OCCUR.

13. 2]STAGE OF ACTIVE ULCERATION:
ACTIVE ULCERATION RESULTS FROM NECROSIS & SLOUGHING
OF THE EPITHELIUM, BOWMAN’S MEMBRANE & THE INVOLVED
STROMA.
THE WALLS OF THE ULCER PROJECT OWING TO SWELLING OF
THE LAMELLAE BY IMBIBITION OF FLUID & PACKING OF MASSES
OF LEUCOCYTES BETWEEN THEM.
HYPEREMIA OF CIRCUMCORNEAL VESSELS RESULTING IN
ACCUMULATION OF PURULENT EXUDATES O THE CORNEA.
EXUDATION INTO THE ANTERIOR CHAMBER FROM VESSELS OF
IRIS & CILIARY BODY LEAD TO HYPOPYON FORMATION.
ULCER MAY FURTHER PROGRESS AS FOLLOWS:
By lateral extension resulting in diffuse superficial ulceration
Or it may progress by deeper penetration leading to
decemetocoele fomation & a possible corneal perforation.

15. 3]STAGE OF REGRESSION:-
INDUCED BY NATURAL HOST DEFENCE MECHANISMS & TREATMENT
THAT AUGMENTS THE NORMAL HOST RESPONSE.
A LINE OF DEMARCATION DEVELOPS AROUND THE ULCER WHICH
CONSISTS OF LEUCOCYTES THAT PHAGOCYTOSE THE OFFENDING
AGENTS.
THE DIGESTION OF NECROTIC DEBRI MAY RESULT IN INITIAL
ENLARGEMENT OF THE ULCER.
THIS PROCESS MAY BE ACCOMPANIED BY VASCULARIZATION THAT
INCREASES THE IMMUNE RESPONSE.
THE ULCER NOW BEGINS TO HEAL & EPITHELIUM BEGINS TO GROW
OVER THE EDGES.

17. 4]STAGE OF CICATRIZATION:-
IN THIS STAGE, HEALING CONTINUES BY PROGRESSIVE
EPITHELIZATION WHICH FORMS A PERMANENT COVERING.
BENEATH THE EPITHELIUM, FIBROUS TISSUE IS LAID DOWN, PARTLY BY
THE CORNEAL FIBROBLASTS & PARTLY BY THE ENDOTHELIUM OF NEW
VESSELS.
THE STROMA THUS THICKENS, PUSHING THE EPITHELIAL SURFACE
ANTERIORLY.
THE DEGREE OF SCARRING FROM HEALING VARIES:-
If the ulcer was very superficial involving only the epithelium, it
heals without scar .
When the ulcer involves Bowman’s membrane, the ulcer is called
a NEBULA.
MACULA results from ulcers involving 1/3rd of corneal stroma.
LEUCOMA results from ulcers involving more than 1/3rd of the
stroma.

18. MACULA OF THE CORNEA VS NEBULA &
LEUKOMA
The 3 words - all from latin-
NEBULA, MACULA & LEUKOMA, are
the words used to describe the
appearance of a corneal scar.
NEBULA (fog/mist) describes a
hard to see corneal scar- one where
slit lamp detection is required.
MACULA (stain/spot) is typified by
the scar in the photo... It can be seen
by proper illumination.
LEUKOMA (white) is a white scar
that is easily seen just by looking at
the eye.

19. LEUKOMATOUS CORNEAL ULCERATION WITH
FATTY INFILTRATION

20. ON PRESENTATION- Eye highly
inflamed with circum corneal congestion
as well as a large nebula macular grade
central corneal opacity.

22. Stages of corneal ulceration..
Regressive
 Progressive
Cicatrization
Leucocytic infiltration
PMN leucocytic infiltration
vascularisation
Active
Ulceration

23. CLINICAL PICTURE (SIGNS AND SYMPTOMS)....
A 50year OLD MAN COMES WITH A HISTORY OF........
PAIN AND FOREIGN BODY SENSATION
WATERING FROM THE EYE
PHOTOPHOBIA
BLURRED VISION
REDNESS OF EYES.
SWOLLEN LIDS.
MARKED BLEPHAROSPASM.
CHEMOSED CONJUCTIVA.
A WELL ESTABLISHED CORNEAL ULCER (characteried
by):-
Yellowish white area of ulcer...may be
oval/irregular.
Margins of ulcer oval and overhanging.
Floor of the ulcer covered by necrotic material.
Stromal oedema present surrounding the ulcer area.