Sclera

Question 1

What is Sclera?

Answer 1

Tough white outer layer of eye. Maintains shape of globe. Provides structural strength an d protects against penetration and rupture of eye- sclera rarely gets inflamed- scleritis.
Extends all around eyeball except cornea.
Anteriorly is conjuctiva , postreiorly connected by delicate connective tissue at tenons capsule

Question 2

Episclera

Answer 2

Thin tissue overlying sclera with minute blood vessels that provide nutrients to sclera. Loose flattened irregular bundles of collage type 1 fibres few blood vessels, fibrocytes, collagen fibrils are uniform which scatters little light and less translucent than. stroma but not as clear as cornea.

Question 3

Scleral Stroma

Answer 3

Layer deeper to episclera, well organised but not to extent as seen in cornea which is why cornea is transparent whilst sclera is white. compact matrix of flattened bundles of type 1 collagen
Fibrils that vary in diameter but mis sclera fibrils 50 to 400nm scatter light giving opaque appearance.

Question 4

Lamina Fusca

Answer 4

innermost layer very delicate layer of pigmented connective tissue- collagen fibres melanocytes, more loosely arranged than rest of sclera. under tenons capsule, fibrocytes

Question 5

Sclera Embryology

Answer 5

formed by 5th month of gestation mostly ectodermal origin but posterior is mesodermal origin coms from mesenchyme at week6-7