Download Bacterial keratitis

Cornea
hystology
Bacterial keratitis
•
•
•
•
•
•
•
•
•
•
•
•
ETIOLOGY: Staphilococcus, Streptococcus, Pseudomonas, Klebssiela
PREDISPOSING FACTORS:
contact lens wear (Pseudomonas);ocular surface disease, trauma, dry
eye;chronic dacryocystitis, administration of topical and systemic
immunosupressive agents;keratorefractive incisional surgery.
DIAGNOSIS:
Acute hypopyon ulcer = severe bacterial inflamation of the cornea
associated with pus in the anterior chamber (hypopyon) and a severe
iridocyclitis;
Streptococccus pneumonie is the usual cause;the corneal ulcer is a dirty
gray color, with overhanging margins + thick mucopurulent exudate
the infection may progress rapidly and result in corneal perforation
Pseudomonas keratitis
is more common in men;the ulcer begins usually centraly;it qiuckly
broodens and deepens, and has a fulminating course
the corneal stroma appears to disolve into a greewish-yellow mucous
discharge;marked anterior chamber reaction and hypopyon
3. Enterobacteriaceae usually cause a shallow ulceration, grey-white
pleomorphic suppuration + diffuse stromal opalescence;
the endotoxins induce ring-shaped corneal infiltrate (“corneal rings”).
Bacterial keratitis – Central ulcer with hypopion
Treatment
•
•
•
•
•
•
•
•
•
•
MANAGEMENT: first step is to collect material by scraping the ulcer with spatula,
stained Gram and Giemsa for cytology and plated on the media
corneal biopsy – when an infection fails to resolve in spite of antimicrobial treatment
initial treatment with concentrated antibiotic eyedrops is based on the result of
Gram stain; after the isolation of te causative organism may indicate specific therapy.
Gram – organisms are treated with aminoglycosisdes(gentamicin, tobramicin);Gram
+ with Cefuroxime and ciprofloxacin; for this reason the initial treatment should be
with a combination of a fortified aminoglycoside + ciprofloxacin;
Subconjunctival injections – in severe infection, particularly when the visual axis is
involved
Sistemic antibiotics are not routinaly used.
The initial antibiotics should be changed only if a resistant pathogen is grown
and the ulcer is progressing.
1% atropine solution – 2 or 3 times daily to prevent the formation of posterior
synechiae and reduce pain from ciliary spasm;
corticosteroids therapy is controversial (only when cultures become sterile ).
It is necessary to keep the dress on the eye; if there is a severe corneal
necrosis a bandage contact lens may be used .
Viral keratitis
Herpes simplex keratitis
•
•
•
•
•
•
•
•
•
•
•
•
•
Is common in 90 % of the population
HSV is subdivided into 2 types:HSV-1 cause facial, oral or ocular lesion;
HSV-2 associated mainly with genital infections
Primary ocular infections appears as a blepharocojunctivites and epithelial
punctate keratitis;
Epithelial infections:
Dendritic ulceration (is cause by live virus):
the disease begins with puncate epithelial opacites that becomes vesicular and
coalesce in a branching linear pattern which staines with fluorescein;
corneal sensitivity is diminished;stromal infiltrates appears under the ulcer;
simptoms: foreign body sensation, lacrimation and decrease in VA
Geographic ulceration : when the epithelium between the dendrites is lost results a
sharply demarcated, irregularily shaped geographic ulcer;
stromal interstitial keratitis – cause by active viral invasion and destruction;
durring the attack stroma shows a cheesey necrotic appearance or a profound
interstitial opacification;may associate anterior uveitis
disciform keratitis – is cause by a reactivated viral infection or an exagerated
hypersensitivity reaction to antigen.It consist of a disc-shaped, localized grayish area
of stromal edema + localized keratic precipitates (the edema may involve the full
thickness of the cornea);
DENDRITIC ULCER
DISCIFORM KERATITIS
•
•
•
•
•
•
•
•
•
•
•
•
•
Treatment
Antiviral drugs:
acycloguanosine – 5 times daily
trifluorothymidine – every 2 hours during the day
idoxuridine
Initial treatment is drops or oiment, after healing has occurred, medication should
be quickly tapered and discontinued by day 14.
Debridement – after topical anesthesia, the cells are removed with moist
cotton-tipped applicator or scalpel blade (the removal of the virus-containing
cells protects adjacent healty cells from infection and eliminated the antigenic
stimulul to stromal inflamation)
Cycloplegic agents – Atropine, scopolamine, midryum
Corticosteroids are indicated only in stromal keratitis (if the visual axis is
involved, topical steroids + antiviral cover).
Dendritic epithelial disease: topical antiviral + debridement;
Stromal keratitis: topical antiviral + topical corticosteroids
Postinfections ulcers: encouraging epithelial healing
The role of sustained antiviral prophylaxis is not clear.
HERPES ZOSTER KERATITIS
Numular keratitis
•
•
•
•
•
•
•
•
•
•
•
•
•
Is caused by human herpes virus 3
Zoster mainly affects elderly patients and is rare in children;
ussualy presents as a combination of 2 or more the following forms:
conjunctivitis, episcleritis, scleritis, keratitis, iridocyclitis and glaucoma;
Keratitis (occurs in about 40% of all patients), as a
Fine punctate epithelial keratitis +/- stromal edema;
Dendritic ulceration (can be mistaken with HSV);
Numular keratitis (multiple fine granular deposits)
Disciform keratitis.
Treatment:
Antiviral sistemic ACYCLOVIR (800mg 5 times daily for 10 days);
FAMCICLOVIR, VALACICLOVIR - decrease the pain, stop visual progression
and reduce incidence and severity of keratitis;
Sistemic steroids – inhibit development of postherpetic neuralgia (must be
limited to patients 50 years of age or older, in severe scleritis, uneitis and orbital
inflamations);
CIMETIDINE – 300mg p.o. qid if periocular edema and pruritus are excessive.
Postherpetic neuralgia is treated with lidocaine gel, amynotripttyline (12,5-25mg).
Topical ACYCLOVIR or trifluridine or topical steroids.
FUNGAL KERATITIS
•
•
•
•
•
•
•
•
•
•
•
after topical administration of corticosteroids and antibiotics
the most common fungi are : Aspergillus, Candida, Fusarium
Clinic: ulcer appears as a greywish – white with a shallow crater,
which is surrounded by a sharply demarcated halo that persist 4
month
Less specific findings include satellite lesion
Scrapping the base and edges of the ulcer is essential for the
diagnosis;
A culture result can be obtained within 48-72 hours
Treatment:
-topical 1% solutions of miconazole, clotrimazol or ketokonazol
-sistemic itraconazol or ketokonazol may be helpful in severe cases
-therapeutic penetrating keratoplasty may be required in unresponsive
cases
-corticosteroids is always contraindicated.
COENEAL LACERATION