Anatomy of retina

1. ANATOMY OF
RETINA
Presented By:
Bhawna
Roll No. 25

2. ANATOMY
• Retina- the innermost tunic of the eyeball
• thin, delicate and transparent membrane, which is the most
developed tissue of the eye.
Retina extends from the optic disc to the ora serrata .
 Retina is the thickest in the peripapillary (0.56mm) and thinnest
at ora serrate (0.1 mm).
GROSS DIVISION OF RETINA:
• Fundus refers to the dome shaped interior of the eyeball. Grossly,
fundus can be divided into two distinct regions:
 Posterior pole
Peripheral retina

3. I)Posterior pole: area of fundus posterior to the retinal
equator(imaginary line which is considered to lie in line with the
exist of the four vena vorticose )
• best examined : slit- lamp indirect bio microscopy using + 78 D
and + 90 D lens and by direct ophthalmoscopy.
• The posterior pole includes two distinct areas: the optic disc and
macula lutea.
1) Optic disc : also known as optic nerve head
• pink coloured, well defined vertically oval area with average
diameter of 1.5mm equal to 1DD (disc diameter).
• The optic disc thus represents the beginning of the optic nerve and
so is also referred to as optic nerve head.

4. • A depression seen in the disc is called the physiological cup.
• The central retinal artery and vein emerges through the
center of this cup.
• Because of absence of photoreceptors (rods and cones), the
optic disc produces an absolute scotoma in the visual field
called as physiological blind spot

5. 2. Macula lutea: also known as yellow spot
• Itis comparatively darker than the surrounding fundus and is situated
at the posterior pole temporal to the optic disc.
• Fovea centralis is the central depressed part of the macula. the most
sensitive part of the retina.
• With lowest threshold for light and highest visual acuity, because it
contains only cones, in its center is a shining pit called foveola
• The tiny depression in the center of foveola is called umbo
• An area about 0.8mm in diameter (including foveola and some
surrounding area) does not contain any retinal capillaries and is
called foveal avascular zone (FAZ).
• Surrounding the fovea are the parafoveal and perifoveal areas.

6. II)Peripheral retina :area bounded posteriorly by the retinal equator and
anteriorly by the ora serrata
peripheral retina is best examined with indirect ophthalmoscopy and goldman
three mirror contact lens

7. MICROSCOPIC STRUCTURE: retina consists of 10 layers ,arranged in
two distinct functional components the pigment epithelium and the
neurosensory retina
1)Pigment epithelium: outermost layer of retina.
• It consists of a single layer of hexagonal cells containing melanin
pigment.
• It is firmly adherent to the underlying basal lamina of the choroid.
• Pigment epithelium provides metabolic support to the neurosensory
retina and also acts as an antireflective layer.
Interphotoreceptor matrix (IPM): present in the potential space
between pigment epithelium and the neurosensory retina

8. 2). Layers of rods and cones: Rods and cones are the end organs of vision and
are also known as photoreceptors.
Layers of rods and cones contains only the outer segments of
photoreceptors cells arranged in a palisade manner.
There are about 120 million rods and 6.5 million cones.
Cones also contains a photosensitive substance and are primarily
responsible for highly discriminatory central vision (photopic vision) and
colour vision.
Rods contains a photosensitive substance visual purple (rhodopsin) and
subserve the peripheral vision and vision of low illumination (scotopic
vision).
3) External limiting membrane :it is a fenestrated membrane ,through which
pass processes of the rods and cones

9. 4) OUTER NUCLEAR LAYER : it consists of nuclei of cones and rods
5) OUTER PLEXIFORM LAYER: it consists of connection of rods spherules
and cones pedicles with the dendrites of bipolar cells and horizontal cells
6) INNER NUCLEAR LAYER : it mainly consists of cell bodies of bipolar
cells.
• it also contain cell bodies of horizontal ,amacrine and muller’s cells and
capillaries of central artery of retina .
• The bipolar cells constitute the first order neurons .
7)INNER PLEXIFORM LAYER :it essentially consists of connections
between the axons of bipolar cells and dendrites of the ganglion cells ,and
processes of amacrine cells
8)GANGLION CELL LAYER : It mainly contains the cell bodies of ganglionic
cells (the second order neurons of visual pathway )

10. There are two types of ganglion cells :
Midget ganglion cells: present in the macular region and the dendrite
of each such cell synapses with the axon of single bipolar cell
Polysynaptic ganglion cells : lie predominantly in peripheral retina and
each such cell may synapse with up to a hundred bipolar cells
9) NERVE FIBRE LAYER (stratum opticum):consists of axons of the
ganglion cells ,which pass through the lamina cribrosa to form the optic
nerve .
10) Internal limiting membrane : it is the innermost layer and
separates the retina from vitreous .
Midget
ganglion
Polysynaptic
ganglionic

11. • It is formed by the union of terminal expansions of the muller’s fibres
,and is essentially a basement membrane

12. STRUCTURE OF FOVEA CENTRALIS :In this area ,there are no rods ,
cones are tightly packed and other layer of retina are very thin .
• Its central part (foveola)largely consists of cones and their nuclei
covered by a thin internal limiting membranes .all other retinal layers
are absent in this region

13. Functional division of retina :retina is divided into temporal
retina and nasal retina by a line drawn vertically through the
center of fovea
• Nerve fibre arising from temporal retina pass through the
optic nerve and optic tract of the same side to terminate in
the ipsilateral geniculate body
• Nerve fibres originating from the nasal retina after passing
through the optic nerve cross in the optic chiasma and travel
through the contralateral optic tract to terminate in the
contralateral geniculate body

14. BLOOD SUPPLY
• Outer four layer of the retina pigment epithelium , layer of rods and
cones , external limiting membrane and outer nuclear layer are
AVASCULAR
• they get their nutrition from the anterior ciliary arteries and
posterior ciliary arteries
• Inner six layer of retina are VASCULAR , get their supply from the
central retinal artery , which is a branch of ophthalmic artery
• Macular region supply by cilioretinal artery
• CENTRAL RETINAL ARTERY : emerges from the centre of the
physiological cup of the optic disc
• Divides into 4 branches :

15. 1)Superior nasal 3) Inferior nasal
2)Superior temporal 4) Inferior temporal
• These are the end arteries, i.e they do not anastomosis with each other
RETINAL VEIN :
• Central retinal vein drains into cavernous sinus directly or through the
superior ophthalmic vein
• Only place where the retinal system anastomosis with ciliary system is in
the region of lamina cribrosa
BLOOD SUPPLY OF OPTIC NERVE HEAD :
 Surface nerve fibres layer: from retinal arterioles
 Prelaminar region : vessels of ciliary region
 Lamina cribrosa region : short posterior ciliary arteries
 Retrolaminar region :supplied by both ciliary and retinal circulation