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CORNEACORNEA
Dr.H.Izar Aziz,SpM(K) 2
Function of the cornea :Function of the cornea :as Window of the globe & refractive
media:• clear & transparent with power +
42 D.• as microorganisms barrier
• Corneal endothelium maintains corneal clarity through:– Acting as a barrier to the aqueous humor– Providing metabolic pump
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Loss of transparency caused by :• endothelial damage• epithelial damage.
Corneal Edema
• Alteration of endothelial function corneal edema
• Acute altered barier effect of the endothelium/epithelium
• Chronic inadequate endothelial pump
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Causes of Corneal Edema
Acute• Trauma (ex: intraocular
surgery)• Inflammation • Hypoxia (ex: contact lens
wear)• Increased intraocular
pressure
Chronic• Trauma or toxins• Fuchs dystrophy• Posterior polymorphous
dystrophy• Iridocorneal endothelial
syndrome• Retained lens fragment
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KeratitisKeratitis : isinflammation of cornea ,caused bymicroorganism infectionantigen antibodies / allergic reaction.
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Epithelium covered by tear film :as a barrier microorganisms infection . (except N. Gonorrhoea)
• Descemet’s membrane as barrier for bacterial infection to COA .(but not for fungus)
• Etiology of keratitis : – Exogenous : bacteria ,fungus , virus, parasite– Endogenous : allergic reaction.
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• Bacteria :-Pure Pathogen : Streptococcus
pneumoniae, Pseudomonas aeroginosa
-Opportunistic bacteria : -Staphylococcus,Moraxella, Serratia(as flora at conjunctiva
. Alcoholic/ B6 deficiency .Topical steroid >>>
. Corneal abrasion
Pathogen bacteriaPathogen bacteria Corneal infection
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• Fungus (usually opportunistic)•Candida, Fusarium, Aspergillus
• Virus– VHS– VVZ
• Parasite : Acanthamoeba in Contact lens user
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Symptoms & Signs• Subjective (patient’s history )
– pain– glare (photophobia)– blur vision – tearing (lacrimation)
• Objective - loupe or slit lamp examination– blepharospasme– ciliary injection – tearing (lacrimation)– superficial infiltrate or corneal ulcer– hypopyon- in advanced cases.
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• Special examinations :– Flourescein test for corneal ulcer– Seidel test for perforating cornea
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Laboratory Studies Etiologic diagnosis.Scraping from:
infiltrate / edge of the ulcerfornices of conyunctiva
Slide Staining :Gram ( for bacteria)Giemsa (for fungus )
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Clinical courseSubepithelial
/epithelial keratitis
Recover without scar
Become corneal ulcer
Recover with scar
NebulaMakula
Leukoma
Perforating cornea, accompanied bulging of the cornea & iris prolaps
Recover with scar :Leukoma adherentstaphyloma cornea
Corneal blindness
Advanced inflamation
-endophtalmitis-panophtalmitis
recover Extirpation of the globe
Abulbi
Phtysis bulbi
Permanent blindness
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Clinical appearance of corneal ulcers
• Serpeginous corneal ulcer.– Etiology : Pneumococcus– acute, well circumscribed – gray ulcer, tends to spread to center of cornea– hypopyon is common (sterile)
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•Pseudomonas ulcer.• Etiology : Pseudomonas aerg. (present in Flourescein
sol.)• bluish-green exudate • very acute ,spread rapidly to all direction ,because proteolytic enzyme destroy the corneal stroma descemetocele
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• Marginal Ulcer – Etiology : Staphylococcus– affect limbal area
• Fungal ulcer– history: agriculture trauma – topical steroid usage >>>>
• gray Infiltrate• thick hypopyon & irregular surface• satellite lesions - in endothelium
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Herpes Simplex keratitis.Etiology : VHS type Icorneal sensibility <<<lesion : filament, punctate, dendritic, disciform
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• Mooren’s Ulcer– Etiology : antigen antibodies reaction– Progressive excavation of the limbus.
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TreatmenTreatmentt • atropine eye drops • Anti microorganisms depend on
laboratory finding (scraping & culture) – Antibiotic for bacteria– Anti fungus for fungal infection– Antiviral for viral infection
• Steroid for Mooren’s ulcer• eye bandage
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• Prognosis depends on :– depth & width of the ulcer
Corneal Corneal scarscar
Dr.H.Izar Aziz,SpM(K) 22
NebulaMakulaLeukomaLeukoma adherent
Central ,-->corneal
blindness-Periphery (No visual disturbance )
Dr.H.Izar Aziz,SpM(K) 23
PreventionPrevention
• Avoid corneal trauma• Avoid overuse of topical
steroid • Cure external eye infection as
soon as possible.• Avoid trigger factor for
relapsing H.simplex keratitis.
Keratoconus• A progressive thinning and bulging of the
central of paracentral cornea cone shape cornea
• 6-8% cases: positive family history• Onset: around puberty
Clinical Findings • Unilateral • High astigmatism and myopic blurred
vision• Munson sign: bulging of the lower lid in
downgaze
Treatment
• Spectacles• Rigid contact lens • Keratoplasty
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Reference Books• Vaughn D, Asbury T; General
Ophthalmology, 15th edition, Appleton & Lange
• Miller S; Parson’s Diseases of the eye, 17 th Edition, Churcill Livingstone, 1984
• Kanski JJ, Clinical Ophthalmology, 4th edition,Oxford Butter Worth Heineman Ltd, 1999