cornea
* Definition :
It is a colorless (transparent) structure
covering the anterior 1/6 of the eye ball.
*Development of the cornea:
- Surface ectoderm forms the epithelium of the cornea.
- Mesoderm gives rise to the corneal stroma.
- Neural crest cells gives rise to the corneal Endothelium.
**Characters of the cornea :-
- colorless (transparent) structure and has a smooth surface.
- A vascular structure.
- Highly innervated by non-myelinated trigeminal nerve fibers.
-The most powerful refractive media of the eye
( 42+ diopters ).
- Diameter :-
- Horizontal = 12mm
- vertical = 11mm Why…?
Due to scleral overlapping on upper
& lower sides of the cornea.
& lower sides of the cornea.
- It is not uniformly curved How…?
>>the central or optical zone having a smaller radius of
curvature than the peripheral parts,and the
posterior surface is more strongly curved than the anterior.
>> Ant radius of curvature = 7.7 mm
>> Post radius of curvature = 6.6 mm
>>Thus the cornea is thinner (0.6 mm) at its
center than near its margin (1 mm).
see you,
Dr Ibrahim
Dr Ibrahim
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