The document summarizes the anatomy and physiology of the anterior and posterior segments of the eye. The anterior segment includes structures like the iris, cornea, lenses, and aqueous humor-filled chambers. The posterior segment consists of the vitreous humor, retina, choroid, and optic disc. Key structures like the iris, ciliary body, choroid, lens, macula, and optic disc and their functions are also described.

1. ANATOMY &
PHYSIOLOGY
OF ANTERIOR AND
POSTERIOR
SEGMENT
Presented by :-
Vishwanath Pratap Singh
Yashaswi Tripathi

3. Anterior Segment
• It includes crystalline lens( which is
suspended from the ciliary body by
zonules), and structures anterior to
it, viz., iris, cornea and two aqueous
humour-filled spaces anterior and
posterior chambers.

4. Anterior chamber
• Bounded anteriorly by
the back of cornea.
• Bounded posteriorly by
the iris and part of ciliary
body.
• About 2.5 mm deep in
the centre in normal
adults.
• Shallower in
hypermetropes and
deeper in myopes.
• Contains about 0.25 ml of
the aqueous humour.

7. UVEA
The uvea comprises the iris and
ciliary body anteriorly and the choroid
posteriorly.

8. Iris
• The iris largely consists of connective tissue
containing muscle fibres, blood vessels and pigment
cells.
• Its posterior surface is lined by a layer of pigment
cells. At its centre is an aperture, the pupil.
• The chief functions of the iris are to control light
entry to the retina and to reduce intraocular light
scatter.
• Pupil dilation is caused by contraction of radial
smooth muscle fibres innervated by the sympathetic
nervous system.

9. Ciliary body
• The ciliary body is a specialised structure uniting
the iris with the choroid.
• It makes aqueous humour and anchors the lens
via the zonules, through which it modulates lens
convexity.
• This is called accommodation and is controlled by
parasympathetic fibres in the oculomotor nerve.
• The posterior part of the ciliary body merges into
the retina at the ora serrata.

10. Choroid
• The choroid, consisting of blood vessels,
connective tissue and pigment cells, is
sandwiched between the retina and the sclera.
• It provides oxygen and nutrition to the outer
retinal layers.

11. Lens
• The discus-like lens comprises a mass of long
cells known as fibres. At the centre these fibres
are compacted into a hard nucleus surrounded by
less dense fibres, the cortex.
• The lens is relatively dehydrated and its fibres
contain special proteins. This is why it is
transparent.

13. Posterior chamber
• It is a triangular space containing 0.06ml of
aqueous humor.
• It is bounded anteriorly by the posterior
surface of iris and part of ciliary body,
posteriorly by the crystalline lens and its
zonules and laterally by the ciliary body.

14. Posterior segment
It includes the structures
posterior to the lens ,viz,
vitreous humor , retina, choroid
and optic disc.

15. Vitreous
• The vitreous body is 99% water but,
vitally, also contains collagen fibrils
and hyaluronic acid, which impart
cohesion and a gel-like consistency.
• The vitreous is adherent to the retina
at certain points, particularly at the
optic disc and at the ora serrata.

16. Functions of vitreous
• Screen out UV and IR light.
• Provide a clear media for optical transmission.

17. HUMAN RETINA
• “It is a light sensitive, very thin
delicate membrane made of
cells present inside the
eyeball”.

18. PARTS OF RETINA
Retinal pigmented epithelium
Neuronal Layer

19. LAYERS OF RETINA
1. Retinal Pigmented Epithelium
2.Photoreceptors
3.Outer limiting membrane
4. Outer nuclear layer
5.Outer plexiform layer
6.Inner plexiform layer
7. Inner nuclear layer
8. Ganglion cell layer
9. Nerve fibers layer
10. Inner limiting membrane

21. At the fundus
there are two
landmarks
Macula lutea
(Also called as
central retina).
Optic disc (Also
called as blind
spot).

22. Macula lutea
• The macula lutea or simply macula is Yellowish
area located infero-lateral to the optic disc and
there is a slightly depression in the center of the
macula called “Fovea centralis”.
• The fovea centralis is the region of sharpest visual
acuity or the region of maximum visual acuity
due to large concentration of only cone cells.
• The macula is avascular area and its diameter is
from 5-6mm .
• It depends on choriocapillaris for blood supply as
it does not get blood supply from central retinal
artery.

24. Optic disc
• The optic disc is a point of retina from where all the
optic nerve fibers are moving out of the retina
through the lamina cribrosa and moving into the
central nervous system as Optic nerve.
• The optic disc located slightly nasally superiorly and
medially. There is also a depression in the optic disc
called physiological cupping which is formed under
certain disease condition like glaucoma.
• The optic disc is deprived of photoreceptors cells
therefore it is termed as a blind spot .

26. Optic nerve
• The ganglion cell axons in the retinal
nerve fibre layer make a right-angled
turn into the optic nerve at the optic disc,
which has no photoreceptor and
corresponds to the physiological blind
spot.

27. • Behind the eyeball these axons become
myelinated.
• Here the optic nerve is surrounded by
cerebrospinal fluid in an anterior extension of
the subarachnoid space and is protected by
the same membranous layers as the brain.