Anatomy of cornea in general

1. Anatomy
Of
Cornea
By Dr Satish S Hadimani
Dept of shalakya tantra
SGR Ayurved Mahavidyalaya,
Solapur

2. Origin
The word cornea has come from
“Kerato”.
The term “Kerato” in Greek means
horn or shield like. Ancient Greek
used to believe that cornea is
derived from same material like that
of thinly sliced horn of animal.

3. Introduction
• The eye is one of the five sensory organs of the
body. The 'window' is the cornea . All light enters
the eye through this window. The cornea receives
the light and bends it into the pupil.
• Avascular, Transparent
• Accounts for 70% of the total refractive power of
the eye(+43D).
• Principle optical surface of the eye.
Refractive indices of different media
through which light enters the eye
Air 1.00
Tear fluid 1.33
Cornea 1.37
Aqueous humor 1.33
Lens 1.42
Vitreous 1.33

4. Dimensions
• Anterior Surface : Elliptical
Diameter: horizontal:11.75mm, vertical:11mm
• Posterior Surface: Circular
Diameter:11.5 mm
Microcornea
when HCD is less
than 10mm
Macrocornea
when HCD is more
than 13 mm

5. • Radius Of Curvature :
The anterior and posterior radii of curvature are 7.8mm
and 6.5 mm .
• Thickness :
The central corneal thickness is 0.52 mm, whereas
periphery is 0.67 mm thick. Central corneal thickness has
direct influence in IOP measurement. The central 5 mm of
the cornea forms the most powerful refracting surface

6. Corneal layers 5

7. Histology:
6 Layers
1. Anterior epithelium
2. Bowman’s membrane
3. Central Stroma
4. Duas layer
5. Descemet’s membrane
6. Endothelium

8. 1.Epithelium
• 50 -90µm thick.
Stratified squamous
type
• Consist of 5-6 layers

9. • Corneal epithelium sheds at regular interval. It takes
normally 7 days for replacement entire corneal epithelium
• Tight junctions in basal cells account for epithelium’s
transparency.
Layers
of
epithe
lium
Description Mit
otic
acti
vity
Basal
Cell
Single layer of
columnar cells
found adjacent
to basal layer
-
Wing
cell
2-3 layers of
cells with
elongated
process
-
Surface
cells
3 layers of
flattened
epithelial cells
with microvilli in
contact with the
tear film.
+

10. 2.Bowman’s membrane
• Binds the corneal stroma anteriorly with basement membrane
of epithelium.
• Not a true elastic membrane.
• Once destroyed , does not regenerate.
• Shows considerable resistance to infection and injury.

11. 3.Stroma
• 0.5mm thick.
• The stroma or substantia propria, occupies about 90% of the
total corneal thickness,
• Composed of collagen fibrils, keratocytes and extracellular
ground substances.
• The lamellae are arranged in many layers(200-250) and are
parallel to each other.

12. • Anterior 1/3 stroma : lamellae are thin( 0.5-30μm wide
,0.2-1.2 μm thick).
• Posterior 2/3 stroma : lamallae are larger ( 100- 200 μm
wide, 1 -2.5 μm thick).

13. Duas layer
• Was discovered by Dr.Harminder singh dua at
the university of nottingham in 2013
• It is the 4th layer 15 microns thick
• Strong layer and impervious to air

14. 5.Descemet’s membrane
• A strong homogenous layer.
• Basement membrane of endothelium.
• Made up of collagen and glycoprotien.
• Elastic.
• It can regenerate . Resistant to chemical agents, infection and
pathological processes.
• On posterior surface it shows Hassel Henle bodies, which
increase with advancing age.

15. 6.Endothelium
• Single layer of flat polygonal cells
• At birth cell density is around 6000 cells/sqmm
• With increasing age the no. of cells is reduced
• Involved in active secretion
and protein synthesis.
• Contains highest no. of
mitochondria next to photoreceptors.

17. Blood supply
• Cornea is an avascular structure.
• Small loops derived from the anterior ciliary vessels invade its
periphery for about 1mm and provide nourishment.
• These loops are not in cornea but in the subconjunctival
tissue which overlaps the cornea.

19. Nerve Supply
• The cornea is one of the most sensitive tissues of the body
and has one of the richest sensory nerve supplies in the body.
• It is supplied by long and short ciliary nerves
from the ophthalmic division of the trigeminal nerve.
• Most are concentrated in the anterior stroma beneath the
Bowman zone and send branches forward into epithelium
• Descemets membrane and endothelium are not innervated

22. At limbus,
•Corneal epithelium becomes bulbar conjunctival
epithelium
•Bowman's membrane becomes continuous with the
lamina propria of the conjunctiva and tenon's capsule.
•Stroma becomes sclera
•Descemets membrane becomes schwalbe's line.
•Endothelium lines the trabecular meshwork and
becomes continuous with the anterior surface of the
epithelium
Junction of Cornea and Sclera - Limbus
Contains
1.Trabecular Meshwork
2.Canal of Schlemn

23. Why cornea has Transparency?
• Tight junctions of the epithelial cells.
• Endothelial pump mechanism.
• Absence of blood vessels.
• Absence of pigments.
• Scarcity of cell nuclei in stroma.
• Uniform structure of stroma.

24. Corneal analysis
• Keratometer
• Confocal microscopy
• Specular microscopy
• AS-OCT
• Orbscan
• Aberrometer
• Pentacam
• Keratoscope
• Video keratoscope
• Oculus topographer
• Ocular response analyser
(OCA)
• 3netra
• Galilie

25. Thank You

26. Anatomy of conjunctiva
By Dr Satish S Hadimani
Dept of shalakya tantra
SGR Ayurved Mahavidyalaya,
Solapur

27. Introduction
• Conjunctiva is a transllucent mucous
membrane which lines the posterior surface
of the eyelids and anterior aspect of the
eyeball.
• Limbus

28. Parts of conjunctiva
1. Palpebral conjuncitva
2. Bulbar conjunctiva
3. Conjunctival fornix

30. Palpebral conjunciva
• Marginal conjunctiva
• Tarsal conjunctiva
• Orbital part of palpebral conjunctiva

32. Structure of conjunctiva
1 Epithelium
2 Adenoid layer
3 Fibrous layer
• Epithelium : 2-5 layered non keratinized
epithelium
• Marginal conjunctiva has 5 layered stratified
squamous epithelium
• Tarsal conjunctiva

34. Glands of conjunctiva
• Mucin secretory glands
• Accessory lacrimal glands
Mucin secretory glands
• Goblet cells
• Crypts of henle
• Glands of Manz
Accessory lacrimal glands
• Glands of Krause
• Glands of wolfring

37. Plica semilunaris
• It is a pinkish cresentric fold of conjunctiva,
present in the medial canthus.

38. Caruncle
• The caruncle is a small, ovoid, pinkish mass,
situated in the inner canthus, just medial to
the plica semilunaris.

39. Blood supply
Three sets blood supply sources :
• 1. Peripheral arterial arcade of the eyelid
• 2. Marginal arcade of the eyelid
• 3. Anterior ciliary arteries
• Palpebral conjunctiva and fornices are supplied
by branches from the peripheral and marginal
arterial arcades of the eyelids.
• Anterior conjunctival arteries

42. Veins and lymphatics
• Conjunctiva drains in to the venous plexus of
eyelids and some around the cornea in to the
anterior ciliary plexus.
Lymphatics :
• Superficial and deep
• From lateral side drain into preauricular lymph
• From medial side drain into the
submandibular lymph nodes.

43. Nerve supply
• Circumcorneal zone of conjunctiva - Long
ciliary nerves
• Rest of conjunctiva ; by the branches from
lacrimal, infratrochlear, supratrochlear,
supratrochlear, supraorbital and frontal
nerves.

44. Thank U