This presentation describes the background of the cornea and the corneal diseases in general, also it describes in detailed manner how to manage the corneal ulcer with its different causes.
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Language: en
Added: Jul 15, 2017
Slides: 68 pages
Slide Content
Diseases of
the Cornea
BY
Amr Mounir.MD
1.OUTER COAT
2.MIDDLE COAT
3.INNER COAT
Three Coats of Eye Ball
Tough Fibrous Coat
Post 5/6
th
of Globe
White & Opaque
Sclera
Radius---12mm
Outer Coat
Tough Fibrous Coat
Ant 1/6th of Globe
Transparent
Cornea
Radius---8mm
Outer Coat
Corneoscleral Limbus
Vertical-------10.6 mm
Horizontal---11.7 mm
Thickness
Central portion----0.52 mm
Peripheral portion----1 mm
Size of Cornea
Three Layers
1. Epithelium & its Basement
2. Stroma & its ant condensation ( Bowman Zone(
3.Endothelium & its Basement (Descemet Membrane(
Structure
From Anterior to Posterior
1. Epithelium
2. Bowman Zone
3. Stroma
4. Descemet Membrane
5. Endothelium
Structure
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
Epithelium
90% of the corneal thickness
Bowman Zone
Lamellar Stroma
Once deformed its typical structure is not restored
Stroma
Descemet membrane
)Regenerates(
Endothelium
Single layer of cells
Cells are tightly bound together
Responsible for dehydration
Never regenerates
Inner Lining
Central cornea is avascular
Corneoscleral limbus is generously supplied by
anterior conjunctival branches of the anterior ciliary
arteries
Aqueous humor and tear film provides nutrients
Blood supply
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
Nerve Supply
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
Cornea
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
Transparency
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
Signs of Corneal Disease
Superficial
2.Punctate epithelial keratitis
It is the hallmark of viral infections.
Swollen epithelial cells
Visible unstained
Stains with rose bengal
Signs of Corneal Disease
Superficial
3.Epithelial Oedema
Sign of
Endothelial decompensation
Severe acute elevation of IOP
Signs of Corneal Disease
Superficial
4.Filaments
Small coma shaped mucus strands lined with
epithelium.
One end attached with epithelium
Signs of Corneal Disease
Superficial
5.Pannus
Inflammatory or degenerative ingrowth of fibro
vascular tissue from limbus
Signs of Corneal Disease
Stromal Lesions
1.Infiltrates
Focal areas of active stromal inflammation
2. Edema
Increased corneal thickness
Decreased transparency
3. Vascularization
Signs of Corneal Disease
A corneal ulcer is an ocular emergency that
raises high stakes of questions about
diagnosis and management.
When a large corneal ulcer is staring you in
the face time isn't in your side.
Despite varying etiologies and presentations,
as well as different treatment approaches ,
corneal ulcers have one thing in common : the
potential to cause devastating loss of vision.
Important Facts
1- Control of infection
2- Control of inflammation
3- Promotion of re-epithelialization –
lubrication – lid
closure – bandage
soft contact lens
4- Prevention of perforation
– tissue adhesive glue
– conjunctival flap
– systemic immunosuppressive agents
Corneal grafting
PRINCIPLES OF MANAGEMENT
OF CORNEAL DISEASE
Pathogens which can produce corneal infection in intact
epithelium.
1.Neisseria gonorrhoeae
2.Corynebacterium diphtheriae
3.Listeria
4.Haemophilus
MICROBIAL KERATITIS
( Bacterial(
Oval, yellow-white, densely opaque stromal
suppuration surrounded by relatively clear cornea
Staph. aureus and strep.
pneumoniae
Greyish-white ulcer with indistinct margins
Surrounded by feathery infilterates
Ring infilterate
Endothelial plaque
Hypopyon
History of vegetable matter
injury
Dull grey infiltrate.
Satellite lesions.
Awareness of those ulcers resembling bacterial
keratitis
Awareness of those caused by yeast better
defined borders
Real flags
Differentiators
Fungal Keratitis
Usually develops in pre-existing corneal disease or
immunocompromised patient
Yellow-white ulcer
Dense suppuration
Candida keratitis
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
DENDRITIC ULCER
Herpes zoster keratitis
Healing corneal abrasion
Pseudodendrites due to soft contact lens
Acanthamoeba keratitis
Drug toxicity
Differential diagnosis
Dentritic ulcer.
Loss of corneal sensation.
Photophobia.
Types of HSV keratitis:
Primary
Recurrent
Dentritic , Geographic , Metaherptica
Diabetic foot in the eye Neurotrophic
Differentiators
Stromal necrotic keratitis
Disciform keratitis
OTHER ENTITIES
Predominantly affects children
Etiology –
Tuberculosis – Delayed
hypersensitivity reaction to staphylococcal or other
bacterial antigen
PHLYCTENULOSIS
Photophobia, lacrimation and
blepharospasm.
PRESENTATION
Conjunctival: Pinkish-white nodule surrounded by
hyperaemia
Corneal: May resolve spontaneously or extend
radially to the cornea. May cause severe ulceration or
perforation.
SIGNS
Short course of topical steroids
Topical antibiotics
TREATMENT