Download CORNEA

1.OUTER COAT
2.MIDDLE COAT
3.INNER COAT
*
Tough Fibrous Coat
Post 5/6th of Globe
White & Opaque
Sclera
Radius---12mm
*
Tough Fibrous Coat
Ant 1/6th of Globe
Transparent
Cornea
Radius---8mm
*
Junction of Cornea and Sclera
Contains
1.Trabecular Meshwork
2.Canal of Schlemn
*
Verticle-------10.6 mm
Horizontal---11.7 mm
Thickness
Central portion----0.52 mm
Peripheral portion----1 mm
*
Three Layers
1. Epithelium & its Basement
2. Stroma & its ant condensation ( Bowman
Zone)
3.Endothelium & its Basement (Descemet
Membrane)
*
From Anterior to Posterior
1. Epithelium
2. Bowman Zone
3. Stroma
4. Descemet Membrane
5. 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)
*Endothelium
Single layer of cells
Cells are tightly bound together
Responsible for dehydration
*
Never 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
*
Superficial
1.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
*
Superficial
2.Punctate epithelial keratitis
It is the hallmark of viral infections.
* Swollen epithelial cells
* Visible unstained
* Stains with rose bengal
*
Superficial
3.Epithelial Oedema
Sign of
* Endothelial decompensation
* Severe acute elevation of IOP
*
Superficial
4.Filaments
Small coma shaped mucus strands lined with
epithelium.
One end attached with epithelium
*
Superficial
5.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 transparency
3. 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
- Fusarium
*
–Aspergillus
* 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 broadspectrum 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:
– Oval
– Globus
Nipple cones
cones
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
*