Corneahystology

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