anatomy of the eyeball

Question 1

what is the fibrous layer

Answer 1

cornea and sclera

Question 2

what is the limbus

Answer 2

the point where cornea meets sclera

Question 3

basics of the cornea

Answer 3

● Highest refraction power in the eye: 40 D.
● Refractive index: 1.376.
● Average diameter: 10–13 mm in adults and 9.5–10.5 mm in newborns.
● Thickness: It is about 535 μm thick centrally and thicker towards the
periphery (660 μm).

Question 4

nutrient supply to cornea

Answer 4

aqueous humour posteriorly and some from the tear film anteriorly.

Question 5

nerve supply of cornea

Answer 5

receiving sensory supply from CNV1 via the long ciliary nerves.
Very sensitive

Question 6

what are the layers of the cornea and their roles

Answer 6

● Epithelial layer: Stratified nonkeratinized squamous epithelium. It has high regenerative potential to injury due to the presence of limbal epithelial stem cells (palisades of Vogt: prominent at superior and inferior limbus).
● Bowman layer: Avascular layer (no regeneration potential) that contains collagen fibres and terminates at the limbus.
● Stromal layer: The thickest corneal layer and is continuous with the sclera at the limbus. It is mainly made up of keratocytes and regularly orientated collagen fibrils (type I collagen). It can undergo scarring and has no regenerative potential.
● Descemet membrane: An elastic layer containing type IV collagen fibres.
● Endothelium: Functions by pumping excess fluid from the stroma to keep
the cornea dehydrated to maintain its transparency.