2. CORNEA
The cornea is a round, convex, transparent,
avascular structure that forms the anterior one-
sixth of the outer coat of eyeball
3. •Vertical diameter is 10.6mm
•Horizontal diameter is11.7mm
•Cornea is thinnest at its center and
thicker at periphery
•Is avascular and devoid of lymphatic
drainage
•Nerve supply is from long ciliary
nerves, a branch of the ophthalmic
division of trigeminal nerve.
•Refractory power = +43diopter
7. Predisposing Factors
1. Corneal epithelial trauma
2. Contact lens Wearers
3. Aqueous tear deficiency
4. Chronic use of Steroids
5. Hypovitaminosis A
8. Pathogenesis of Corneal ulcer
Occurs through four stages:
1) Infiltrative stage: Injury to epithelium causes
inflammation, with PMN cell infiltrates and
edema, giving rise to a yellow/white corneal
opacity
2) Active stage: Necrosis and sloughing off of
epithelium causing ulcer formation.
3) Regressive stage: A line of demarcation
develops around the ulcer consisting of
leucocytes while the surrounding cornea
becomes clear. This is induced by treatment or
natural host mechanisms.
4) Cicatrization stage: Healing by
21. Signs
Greyish white ulcer that has delicate fine
feathery edges
Elevated surface & irregular contour
Endothelial plaque may be present
Progressive infiltration, may be
surrounded by stellate lesions
Immune ring
Ciliary congestion
Yeast: Yellow white ulcer with dense
suupuration
22.
23. Management
History & Examination
Investigation
Baseline
Giemsa , KOH and methamine silver stain
Culture
Treatment
25. Protozoal keratitis
Acanthamoeba spp.
Microsporidea
o Acanthamoeba is free living ubiquitous
protozoa found in fresh water and soil
o Active trophozoite or dormant cyst
32. Herpes Simplex keratitis
DNA virus of he Herpesviridae Family
Infection is extremely common
Major cause ofunilateral corneal scarring
worldwide
TYPE 1
Predominantly causes infection above the waist.
Droplet infection or close contact with infected
individual
TYPE 2
Below the Waist (genital herpes)
STD
Genital secretions - Birth
33. Primary infection
Infection in early life
Uncommon during first six months
Subclinical causing mild fever and malaise
Virus eventually travels up the axon of sensory
nerves into its ganglions.
Type 1 remains dormant in trigeminal ganglion
Type 2 in spinal ganglia.
Ocular involvement
Blepharitis
Acute Follicular Conjunctivitis
Epithelial Punctuate Keratitis
Pathogenesis
34. Recurrent keratitis
Poor health
Exposure to ultraviolet rays
Fever
Psychatric disturbance
Use of steroids.
Lesions
Acute/Active Epithelieal Keratitis
Stromal Keratitis
Kerato uveitis.
35. Clinical Features of HSV keratitis
Symptoms
Foreign Body Sensation
Lacrimation – Watery discharge
Photophobia
Pain (mild to moderate)
Reduced Vision
Signs
Ciliary congestion
Diminished corneal Sensitivity
36. Active epithelial keratitis: Dendritic ulcer
Most characteristic lesion, occurs in corneal
epithelium
Typical branching, linear pattern with
feathery edges and terminal bulbs at ends.
Visualized by fluorescein staining
HSV dendritic ulcer stained
with fluorescein
41. o Active viral invasion and destruction of Endothelium
of cornea
Signs
Stroma appears cheesy and necrotic.
Keratic precipitates or KP bodies (Anterior Uveitis)
Features of AEK may be present.
Stomal Necrotic Keratitis
Treatment
Topical Antivirals
Topical Antibiotics
Topical Cycloplegics
Lubricants/Pressure patching Bandage contact lens
42.
43.
44. Disiform Keratits
Definition: It is viral endothelitis in
which there is disc shaped grey area
of stromal edema with localised
keratic precipitates
o Reactivated viral infection of
keratocytesand Endothelium
o Hypersensitivity reaction to viral
antigen
45. Clinical Features
Central zone of epithelial
edema
Stromal thickening - edema
Folds in descemet;s
membrane
Mild to moderate anterior
uveitis
Keratic precipitates
Reduced corneal sensitivity
55. References
Jack J. Kanski's Clinical
Ophthalmoscopy a Systemic
Approach fifth edition
Infective keratitis lecture by Dr.
Shabbir Hussain, Department of
Ophthalmology
Edward S. Harkness institute,
columbia university college of
physicians and surgeons
Clinical Opthalmology; Shafi M.
Jatoi