2. *Keratitis is a descriptive term for any type of corneal
inflammation
*Characterized by corneal edema, cellular infiltration and ciliary
congestion
*Microbial Corneal ulcer is corneal epithelial defect caused by
microorganisms with underlying stromal infiltrate
*Microbial Keratitis is one of the leading causes of preventable
blindness
*
4. *
A) Ulcerative Keratitis ( Corneal Ulcer)
1. Depending Upon Location
2. Depending Upon Purulence
3. Depending Upon Association Of Hypopyon
4. Depending Upon Depth Of Ulcer
5. Depending Upon Slough Formation
B) Non - Ulcerative Keratitis
1. Superficial Keratitis
2. Deep Keratitis
5. *
A)Infective or Microbial Keratitis
B)Allergic
C)Trophic
D)Associated with skin and mucous membrane
diseases
E)Associated with systemic collagen vascular
diseases
F)Traumatic
G)Idiopathic
16. 1] EXOGENOUS INFECTION:- 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
*Source of infection
17. THERE ARE 2 MAJOR FACTORS IN THE PRODUCTION OF A
ULCER:-
A]CORNEAL
EPITHELIAL
DAMAGE
B]INFECTION
OF THE
ERODED
AREA
HOWEVER, THE FOLLOWING
ORGANISMS CAN INVADE AN
INTACT CORNEAL EPITHELIUM AND
PRODUCE ULCERATION....
Neisseria gonorrhoea
N.meingitidis
Corynebacterium diptheriae
H influenzae
*Pathogenesis
20. Infiltration of lymphocytes into the epithelium & the underlying
stroma from the peripheral circulation
Subsequently, necrosis of the involved tissue may occur
1.Stage Of Progessive Infiltration
21. 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 of the cornea
Exudation into the anterior chamber from vessels of
iris & ciliary body lead to hypopyon formation
2.Stage Of Active Ulceration
22.
23. 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
Digestion of necrotic debri may result in initial enlargement of the ulcer
Accompanied by vascularization that increases the immune response
The ulcer now begins to heal & epithelium begins to grow over the edges
3.Stage of Regression
24. 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
Stroma thus thickens, pushing the epithelial surface anteriorly
The degree of scarring from healing varies
Nebular / macular / leucomatous opacities
4.Stage Of Cicatrization
26. *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
28. *
*Infiltration within stroma and epithelium
*Overlying epithelial defect
*Lid Erythema and edema
*Conjuctival injection and chemosis
*Discharge
*Conjuctival papillary response
*Anterior chamber inflammation
29. *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
30. 2.Pneumococcal
* Ulcer serpens
*Tendency to creep over the
cornea in serpiginous fashion
*After trauma
*Starts at periphery & spreads
towards centre
*Violent iridocyclitis is often
associated with it
*Hypopyon – always present
*It has great tendency for
PERFORATION
*After corneal trauma,
dacrocystitis, bleb infection
32. 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.
33. *
*Type of stromal keratitis
*Crystalline 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
*Most common organism Strep.
Viridans
34. *Fungal keratitis
*Ubiquitous organisms
*Classification : Filamentous, Yeasts & Diphasic forms
*Filamentous - Multicellular with branched hyphae, can be
septate or aseptate e.g. aspergillus, fusarium
*Yeast – Unicellular, reproduces by budding, pseudohyphae in
tissues e.g. candida, cryptococcus
*Aspergillus is most common followed by fusarium and
candida
35. Gram's stain of scraping from Fusarium corneal ulcer demonstrating
branching fungal hyphae
36. *Predisposing Factors
* Trauma by vegetative matter
*Long term steroid use
*Immuno-compromised states
*Contact lens users
*Post surgery
*Chronic keratitis
37. *Clinical Features
*Symptoms are much milder than signs would suggest
*Dry looking infiltrate
*Hyphate or feathery edges
*Satellite lesions
*Endothelial plaque
*Brown pigmentation in fungal keratitis may be due to the
presence of dematiaceous fungi
41. Filamentous fungi Yeasts
Occurs more frequently in young people
(occupational and outdoor activity),
usually no predisposing factor.
Usually occurs in an
immunocompromized host, preexisting
corneal disease or steroid treatment.
Involved area can be localized and is
often elevated; epithelial defect may or
may not be present;
Usually more focal, elevated and
suppurative, resembling bacterial keratitis
Often has feathery edges and satellite
lesions.
Edges not feathery and satellitism not
usually seen.
CL wear induces microtrauma & epi edema d/t hypoxia. Pseudomonas is most commonly asso with CL induced MK. Followed by staph n serratia.
Surg: PK, RK, Astig keratotomy
Is to be done at the widest dimension and also at 90 degrees to it. Done by using a thin beam to eliminate parallax. Serial measurements help in assessing response.
