The document discusses the cornea, which is the transparent outer layer of the eye. It has five layers, with the stroma making up 90% of the corneal thickness and containing collagen that gives the cornea its structure and elasticity. The cornea focuses light onto the retina and acts as a protective barrier for the eye. One disease that can affect the cornea is keratoconus, where the cornea thins and bulges into a cone shape, causing vision problems. Keratoconus can be managed through contact lenses, collagen cross-linking treatment, corneal grafting, or corneal ring implants.

1. B Y T I N A
THE CORNEA

2. OUTLINES
 INTRODUCTION
 FACTS
 LAYER OF THE CORNEA
 FUNCTION

3. INTRODUCTION
 It’s the outer most layer of the eye, domed shaped,
transparent tissue that covers the eyes.
 It has about three quarters of the optical power of
the eye
 its is inserted into the sclera at the limbus, its
about 540 micrometer thick centrally

5. FACTS!!!
 Did u know!!! the cornea is the mostly densely
innervated tissues in the body!!
 Supplied by the first branch of trigeminal nerve
 It has no blood vessels although its alive, it
receives all the nutrients from the aqueous humor
(posteriorly) and tears (anteriorly).

6. Cornea transparency is due to;
 Uniform structure
 A vascularity
 Deturgescence (relative dehydration)

7.  cornea has five layers ;
i) The epithelium;
 Is stratified squamous and non keratinized
 It has nerve endings
 acts as a barrier of the eye to the foreign material
eg dust.
 It absorb oxygen and nutrients form tears

8. ii) Bowman’s membrane
 Its formed by collagen fibres, when injured it forms
scar as it heals, if the scar will form centrally the
there will be visual loss.

9. iii) The stroma
 It contribute to about 90% of the corneal thickness.
 Its mainly water and collagens, collagens are the
ones which gives the cornea its structure and
elasticity.
 The stoma can scar but can not regenerate.

10. iv) Descement’s membrane
 It has a regenerative potentials

11. v) The endothelium
 It maintain corneal deturgescence by pumping
excess fluid out of the stoma, failure of
endothelium to do its work can lead to cornea
edema
 Its cells cannot regenerate.
 There is loss of cells in this layer as the age
increases

12. DIAGRAM

13. FUNCTION OF THE CORNEA
 It helps in focusing the light that come into the eye
so as it can fall on the retina.
 It’s a physical barrier together with tears and eyelid
against the dirty and germs that come into contact
with the eye.
 It also protect the eye against the UV light from the
sun.

14.  The cornea can be affected by different diseases,
keratoconus being among them

15. KERATOCONUS
 It’s a disease characterized by progressive thinning
of the cornea and takes a cone shape which results
to astigmatism (the cornea cannot focus the light
to the retina).
 Most of refraction of light occurs at the air –cornea
interface so change in the cornea shape can lead to
major impact on vision.

16. Signs
 Bulging of the lower eyelid on down
gazing(munson sign)
 Oil droplets reflex on direct ophthalmoscope
 Scissors reflex on retinoscopy
 Stromal scarring this occurs when descement’s
membrane has rupture

17.  Some research suggest that its due to imbalance of
enzymes in the cornea which leads to oxidative
damages leads to weakening and bulging of the
cornea.
 Overexposure to the ultraviolet light,
 Excessive rubbing of the eye ,
 Poor fitted contact lens
 Genetic predisposition.
CAUSES OF KERATOCONUS

18. Can glasses correct the keratoconus?
 Glasses can only correct the regular astigmatism but
as for keratoconus it is an irregular astigmatism.
 Contact lenses can be used to make the air –cornea
interface more spherical so as the light can focus to
the eye.

19. MANAGEMENT OPTIONS
 Contact lenses
 Collagens cross linking; it prevent the progression of
early form of the disease (riboflavin eye drops which
is then exposed to the sun light)
 Corneal graft
 Corneal ring segment implant

20. THANK YOU !!!!!!