1.OUTER COAT 2.MIDDLE COAT

3.INNER COAT

Tough Fibrous CoatPost 5/6th of GlobeWhite & Opaque

ScleraRadius---12mm

Tough Fibrous CoatAnt 1/6th of Globe

TransparentCornea

Radius---8mm

Junction of Cornea and Sclera

Contains 1.Trabecular Meshwork

2.Canal of Schlemn

Verticle-------10.6 mmHorizontal---11.7 mm

ThicknessCentral portion----0.52 mmPeripheral portion----1 mm

Three Layers

1. Epithelium & its Basement2. Stroma & its ant condensation ( Bowman

Zone)3.Endothelium & its Basement (Descemet

Membrane)

From Anterior to Posterior

1. Epithelium2. Bowman Zone3. Stroma4. Descemet Membrane5. Endothelium

*50-60 µm thick*Covers the stroma anteriorly*Continuous with epithelium of conjunctiva*Life of epithelial cells is 7 days*Prevent aqueous solutions to penetrate

*Surface cell layer*Wing cell layer*Basal cell layer*Basement membrane

90% of the corneal thickness

*Bowman Zone*Lamellar Stroma

Once deformed its typical structure is not restored

*Descemet membrane (Regenerates)

*EndotheliumSingle layer of cellsCells are tightly bound togetherResponsible for dehydrationNever regenerates

*Central cornea is avascular*Corneoscleral limbus is generously

supplied by anterior conjuntival branches of the anterior ciliary arteries*Aqueous humor and tear film provides

nutrients

*Branches of the ophthalmic division of trigeminal nerve and are solely sensory*Most are concentrated in the anterior stroma beneath the Bowman zone and send branches forward into epithelium*Descemet membrane and endothelium are not innervated

*The microvilli of the anterior surface of the squamous cell layer are wet by the mucin of tear film*These cells are joined by tight junctions

that exclude water soluble substances

*Tight junctions of the epithelial cells*Endothelial pump mechanism*Absence of blood vessels*Absence of pigments*Scarcity of cell nuclei in stroma*Regular structure of stroma

Superficial1.Punctate epithelial erosions Tiny ,slightly depressed, epithelial defects which stain with flourescein but not with rose Bengal

PEE are non specific and may develop in a wide variety of keratopathies

Superficial2.Punctate epithelial keratitis It is the hallmark of viral infections.*Swollen epithelial cells*Visible unstained*Stains with rose bengal

Superficial3.Epithelial Oedema

Sign of*Endothelial decompensation*Severe acute elevation of IOP

Superficial4.Filaments

Small coma shaped mucus strands lined with epithelium.

One end attached with epithelium

Superficial5.Pannus

Inflammatory or degenerative ingrowth of fibro vascular tissue from limbus

Stromal Lesions

1.Infiltrates Focal areas of active stromal inflammation

2. Oedema Increased corneal thickness Decreased transparency3. Vascularization

Lesions of Descemet Membrane

1. Breaks Corneal enlargement Keratoconus Birth trauma

2. Folds (Striate Keratopathy) Surgical trauma Ocular hypotony Stromal oedema

* Control of infection* Control of inflammation* Promotion of re-epithelialization – lubrication – lid closure – bandage soft contact lens *Prevention of perforation – tissue adhesive glue – conjunctival flap – systemic immunosuppressive agents* Corneal grafting

*Ocular surface disease: Trauma, post-herpetic corneal disease, bullous keratopathy, corneal exposure, dry eye and diminished corneal sensation.*Contact lens wear

Pathogens which can produce corneal infection in intact epithelium.*1.Neisseria gonorrhoeae*2.Corynebacterium diphtheriae*3.Listeria*4.Haemophilus

*Oval, yellow-white, densely opaque stromal suppuration surrounded by relatively clear cornea

*Thick mucopurulent exudate, diffuse liquefactive necrosis and semi-opaque ground glass appearance of adjacent stroma

*Shallow ulceration, grey-white pleomorphic suppuration and diffuse stromal opalescence. Endotoxins may induce ring-shaped corneal infilterates

*History*Clinical examination (including staining

and sensitivity)*Hospitalization*Corneal scrapping*Treatment

*Topical antibiotics – combination therapy with fortified amino glycoside and fortified cephalosporin or monotherapy with fluoroquinolone. Initial instillation at hourly intervals.*Subconjunctival injections*Systemic ciprofloxacin 750mg BD

*Cycloplegics*Steroid therapy (controversial)*Corneal biopsy or excisional keratoplasty

*Wrong diagnosis*Wrong treatment*Drug toxicity

*Filamentous fungal keratitis –Aspergillus - Fusarium

*Greyish-white ulcer with indistinct margins*Surrounded by feathery infilterates*Ring infilterate*Endothelial plaque*Hypopyon

*Usually develops in pre-existing corneal disease or immunocompromised patient*Yellow-white ulcer*Dense suppuration

*Suppurative bacterial keratitis*Herpetic stromal necrotic keratitis

*Culture*Biopsy*Antifungal therapy – Initially broad-spectrum econazole 1% topically – Then depending upon sensitivity natamycin or imidazole for 6 weeks*Systemic ketoconazole*Therapeutic penetrating keratoplasty

*Protozoan –active (trophozoite) –dormant (cystic)*Common in swimmers and CL wearers

*Blurred vision and disproportionate pain*Patchy anterior stromal infilterates*Perineural infilterates (radial keratoneuritis)*Infilterates coalesce –ring abcess, ulceration and hypopyon*White satellite lesions

*Corneal scrappings stained with calcoflour white*Corneal biopsy*Treatment with chlorhexidine, polyhexamethylenebiguanide drops, dipropamidine and propamidine.*Therapeutic penetrating keratoplasty

Primary ocular herpes: - Blepharoconjunctivitis - Keatitis (punctate epithelial)

*Opaque cells arranged in a course punctate or stellate pattern*Central desquamation leads to a linear branching ulcer. –Fluorescein stain – Rose Bengal stain –Diminished corneal sensitivity*Anterior stromal infilterates*Geographical or amoeboid ulcer

*Herpes zoster keratitis*Healing corneal abrasion*Pseudodendrites due to soft contact lens*Acanthamoeba keratitis*Drug toxicity

*Antiviral therapy – Acycloguanosine 3% ointment – Trifluorothymidine 1% drops – Adenine arabinoside 3% ointment, 0.1% drops – Idoxuridine*Debridement (with sterile cotton-tipped bud 2mm beyond the edge of ulcer)

*Stromal necrotic keratitis*Disciform keratitis

*Predominantly affects children*Etiology

– Tuberculosis – Delayed hypersensitivity reaction to staphylococcal or other bacterial antigen

*Photophobia, lacrimation and blepharospasm.

*Conjunctival: Pinkish-white nodule surrounded by hyperaemia*Corneal: May resolve spontaneously or

extend radially to the cornea. May cause severe ulceration or perforation.

*Short course of topical steroids*Topical antibiotics

*Onset at puberty*Central or paracentral stromal thinning*Apical protrusion*Irregular astigmatism*Autosomal dominant transmission with

incomplete penetrance proposed

*By keratometry: - Mild (< 48 D), - moderate (48-54 D) - severe (> 54 D)*By morphology: -

Nipple cones – Oval cones – Globus cones

*Ophthalmoscopy: Oil droplet reflex*Retinoscopy: Irregular scissor reflex*Keratometry: Irregular astigmatism (principal meridians no longer 90 degree apart and mires cannot be superimposed)*Placido disc: Irregular reflected ring*Slit-lamp: Very fine deep stromal striae (Vogt lines).

*Decreased visual acuity*Munson sign*Fleischer ring*Corneal scarring*Acute hydrops

*Spectacle correction*Contact lenses*Penetrating keratoplasty