Cornea hystology

1. Corneahystology

2. 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. Enterobacteriaceaeusually cause a shallow ulceration, grey-white pleomorphic suppuration + diffuse stromal opalescence; • the endotoxins induce ring-shaped corneal infiltrate (“corneal rings”).

3. Bacterial keratitis – Central ulcer with hypopion

5. 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 .

6. Viral keratitis

7. 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 infectionsappears 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);

8. DENDRITIC ULCER

9. DISCIFORM KERATITIS

10. 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.

11. HERPES ZOSTER KERATITIS

12. Numular keratitis

13. 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.

14. FUNGAL KERATITIS

15. 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.

17. COENEAL LACERATION