anatomy of sclera

1. ANATOMY OF SCLERA

2. Anatomy of sclera
 Introduction
 Gross Anatomy
 Layers
 Blood supply and nerve supply
 Functions

4. INTRODUCTION
 Sclera forms the Posterior 5/6 th of external tunic, connective
tissue coat of eyeball
 Its whole surface covered by tenon’s capsule
 Anteriorly covered by bulbar conjunctiva
 Inner surface lies in contact with choroid
 With a suprachoroidal space in between

6.  Thickness varies with age
 Thinner-children than elder, Female than male
 Thickest- posteriorly(1mm)
 Gradually becomes thinner when traced anteriorly
 Thin at insertion of extraocular muscle(0.3mm)
 Thickness at equator is 0.4-0.6mm

7. Special regions of sclera
1. Scleral sulcus
2. Scleral Spur
3. Lamina cribrosa

8. 1.Scleral sulcus
 It is an furrow on the Inner surface of the anterior most point of the
sclera near the limbus
 It houses the schlemm’s canal
2.Scleral spur
 It is an annular structure in the anterior most part of sclera
 Appear wedge shaped in cross section
 Longitudinal fibers of ciliary muscle is attached to it
3.Lamina cribrosa
 Is a mesh like structure present behind optic disc
 It allows the fibers of optic nerve to pass through it and act as pressure
barrier between I.O space and retrobulbar space
 In primary open angle glaucoma the IOP increases ,the lamina cribrosa
gradually increases

10. Scleral apertures:-
1.Posterior aperture-around the optic nerve
-transmit long and short ciliary nerves and vessels
2.Middle apertures -4-7mm posterior to equator
-pass vena verticosae
3.Anterior apertures -3-4mm away from the limbus
-transmit anterior ciliary vessels, perivascular
lymphatics, ciliary nerves

11. Microscopic structure
. Consist of three layer:-
1.Episcleral tissue
 thin ,dense , vascularised layer of connective tissue
 Covers the sclera proper
 Fine fibroblasts, macrophages and lymphocytes present in this layer
2.Sclera proper
 Avascular structure
 Consists of dense bundles of collagen fibers crossing each other in all directions
which makes the sclera opaque
 As age advances Scleral collagen fibers tend to sclerosed and also there is
deposition of lipid, which makes Sclera yellow

12. 3 .Lamina fusca
 Innermost
 Blends with suprachoroidal and Supraciliary lamina of the uveal tract
 It is brownish in colour owing to the presence of pigment cells

13. Blood supply:-
 Episclera-anterior and posterior ciliary arteries
 Sclera proper –avascular
Nerve supply:-
 Anteriorly-long ciliary nerves
 Posteriorly-short ciliary nerves

14. Functions:-
 Protects the intraocular component from trauma, light and mechanical
displacement.
 Withstands the considerable expansive force generated by the intraocular
pressure maintaining the shape of the globe.
 Provides attachment sites for the extraocular muscles.

15. Thank you…