This document discusses diseases of the cornea. It provides details on the anatomy, layers, nerve supply, nutrition, and functions of the cornea. It describes pathological changes such as keratitis, corneal abrasions, ulcers, and opacities. It discusses infective keratitis in terms of pathogenesis, predisposing factors, common bacterial causes, symptoms, signs, and complications. The management of bacterial keratitis and treatment of uncomplicated versus perforated ulcers is also summarized.
4. Thickness centre 0.5-0.6 (thinner)
periphery 1.0-1.2mm
Radius of ant.surface 7.8mm
curvature post surface 6.5mm (steeper)
Refractive index 1.376
Refractive power - + 45D (70% Of total
refractive power of the eye
6. Epithelial Layer – Regenerates
Bowman’s Layer- Resistant to trauma and
infection
Stroma – Collagen bundles with keratocytes
Descemets layer- very tough
Endothelium – hexagonal cells –
3000cells/mm2
7. Limbus
1-1.5 mm
anatomy
Cells at limbus are unique – Limbal stem
cells
Responsible for growth and regeneration of
epithelial cells
8. NERVE SUPPLY OF CORNEA
5th cranial nerve (Trigeminal)
Ophthalmic division
Nasociliary branch
Long ciliary nerves
Annular plexus around limbus
Subepithelialplexus Intraepithelial plexus
Cornea has body’s highest no. of nerve endings
9. NUTRITION METABOLISM
Perilimbal capillaries
Aqueous humour
(glucose diffussion)
Atmospheric oxygen
(tear film)
Epithelium &
endothelium
metabolically very
active
Both aerobic &
anaerobic metabolism
10. CORNEAL TRANSPARENCY
Avascularity
Uniform refractive Index of the cornea
Arrangement of corneal lamellae
State of relative dehydration(78%)
Barrier effect Endothelial Osmotic
of epithelium pump gradient
& endothelium
11. FUNCTIONS OF CORNEA
Transmission of light/Refractive medium
Structural integrity of globe/Protects the eye
12. PATHOLOGICAL CHANGES IN
THE CORNEA
Keratitis Superficial
Deep Stromal
Endothelial
Corneal abrasion/erosion
Corneal ulcer
Corneal opacity Nebular, Macular, Leucomatous
Corneal oedema
Vascularisation
18. Bacterial corneal ulcers
Agents :
Staphlococcus aureus/ albus
Streptococcus
Pseudomonas
Pneumococcus
N. gonorrhoeae
C. diphtheriae
E. coli
19. PATHOLOGY OF LOCALISED
CORNEAL ULCER
Stage of progressive infiltration-
progression of ulceration with leucocytes
infiltration and purulent suppuration
Stage of ulceration- desquamation of the
epithelium and tissue necrosis resulting in
saucer shaped ulceration
Stage of regression – characterized by
relatively smooth and transparent ulcer area
Cicatrization – Scar formation
20. STAGE OF PROGRESSIVE
INFILTRATION & ULCERATION
Saucer shaped ulcer
Walls project above normal surface
Grey zone of infiltration
Hypopyon
Progress laterally or deeper
21. Stage of regression
Line of demarcation
Necrotic material shed off
Begins to heal
Vascularisation
22. Stage of cicatrisation
If epithelium only-no scar
NEBULAR- bowman’s membrane & superficial
stroma
MACULAR- upto half of stroma
LEUCOMATOUS-more than half of stroma
Corneal facets
29. Enterobacteriae (E. coli, Proteus species,
and Klebsiella species)- shallow ulcer with
greyish white pleomorphic suppuration and
diffuse stromal opalescence.
The endotoxins may produce ring-shaped
corneal infiltrate.
30. Pseudomonas - produce an irregular sharp
ulcer with thick greenish mucopurulent
exudate.
Diffuse liquefactive necrosis and
semiopaque (ground glass) surrounding
cornea.
31. Hypopyon corneal ulcer
Cause- pneumococcus
Source of infection-Chronic dacryocystitis
Predisposing factors-virulence of organism
-resistance of the tissue
Common in old debilitated or alcoholics
32. Dev.of hypopyon
Iritis due to bacterial toxins
Outpouring of leucocytes from vessels
Leucocytes gravitate to bottom of AC
Hypopyon (sterile & mobile )
33. Signs
Ulcer serpens –greyish
white/yellowish disc shaped ulcer
near centre of cornea
Starts at periphery & spreads towards
centre
Tendency to creep over the cornea in
serpiginous fashion
Iridocyclitis
Hypopyon
Perforation tendency +
40. TREATMENT
OF BACTERIAL KERATITIS
UNCOMPLICATED ULCER
Identify & treat the cause
Corneal scraping
staining/culture
topical Antibiotics-ciprofloxacin 0.3%
-Ofloxacin 0.3%
-gatifloxacin 0.3%
Rest to eye Cycloplegics- 1% atrophine
Antiglaucoma medications
Systemic antibiotics and analgesics
Hot fomentation,dark googles
41. Treatment of Non-healing ulcer
of uncomplicated type
Removal of any known cause of non-
healing corneal ulcer-local,systemic
Mechanical debridement of ulcer
Cauterisation of ulcer
Bandage soft contact lens
Peritomy