The document discusses the anatomy and layers of the retina. It notes that the retina has 10 layers and extends from the optic disc to the ora serrata. The posterior pole, which includes the optic disc and macula lutea, contains the thickest areas of the retina. The 10 layers of the retina are described in detail, including the retinal pigment epithelium, rods and cones layer, and the various nuclear, plexiform, ganglion and nerve fiber layers. Specific structures like the fovea centralis and its avascular zone are also explained.

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Mr. Askar.P. K,
HOD & Associate Professor Of Optometry

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ANATOMY
• Inner most layer
• Thin, delicate & transparent membrane
• Appears purplish red due to underlying
visual purple of the rod & vascular
choroid

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• After death –white opaque
• Retina extends from optic disc to ora
serrata
• Grossly divided in to two
• Posterior pole & peripheral retina

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• Posterior pole & peripheral retina
separated by retinal equator
• Retinal equator is the imaginary line

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POSTERIOR POLE
• Posterior to the retinal equator
• It includes two areas optic disc &
macula lutea
• It is best examined by slit lamp indirect
biomicroscopy & direct ophthalmoscopy

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• Thickness –posterior pole:
• Periphery- .56mm
• Equator- .18- .2mm
• Orra serrata- .1mm

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OPTIC DISC
- It is pink coloured
- Well defined circular area of 1.5mm in
dia

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- All retinal layers terminate except nerve
fibres
- Nerve fibres pass through lamina
cribrosa in to optic nerve

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• Compare to retina appears white
opaque due to lamina cribrosa
• A depression seen in the disc called
physiological cup
• Central retinal artery & vein emerge
through the centre of this cup

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MACULA LUTEA
• It is also called yellow spot

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• It is deeper red
• Situated in posterior pole temporal to
optic disc
• It is 5.5mm in dia

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• Fovea centralis is the central depressed
part of the macula
• Fovea centralis 1.85mm in dia
• Most sensitive part of the retina

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• In its centre shinning pit called foveola
• Foveola dia 0.35mm
• Not contain any retinal capillaries

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• Also called foveal avascular zone
• Surrounding fovea are parafoveal &
perifoveal areas
• It is 0.5mm & 1.5mm in dia resp.

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FOVEA CENTRALIS
• No rods , cones are packed tightly

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• Foveola largely consists of cones & their
nuclei covered by thin internal limiting
membrane
• Other retinal layers absent in this region
• Cone axons arranged obliquely henle’s
layer to reach the margin of the fovea

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• PERIPHERAL RETINA
• Area bounded posteriorly by retinal
equator & anteriorly by ora serrata

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• Best examined by indirect
ophthalmoscopy

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• ORA SERRATA
• It is the peripheral margin where retina
ends & ciliary body start
• Here retina attached to vitreous &
choroid
• Pars plana extends anteriorly from ora

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• 1. pigment epithelium
• 2.Layer of rods & cones
• 3.external limiting membrane
• 4.outer nuclear layer
• 5.outer plexiform layer

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• 6.inner nuclear layer
• 7.inner plexiform layer
• 8.ganglion cell layer
• 9.nerve fibre layer
• 10.internal limiting membrane

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RETINAL PIGMENT EPITHELIUM
• Outer most layer
• Consists of single layer

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• Hexagonal shaped cells containing
pigment
• Firmly attached to underlying bruch’s
membrane (choroid layer)
• Loosely attached to the layer of rods &
cones

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• Space btw RPE & sensory retina is
called subretinal space
• Fluid btw two layers is called subretinal
fluid
• Separation of RPE from the sensory
retinal called RD

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• Play imp role in vit. A recycling &
photoreceptor renewal
• Maintain subretinal integrity by forming
blood retinal barrier
• Give mechanical support to photoreceptor

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LAYER OF RODS & CONES

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• Rods & cones are end organs of vision
• Also called photoreceptors

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• Rods contain photosensitive substance
(rhodopsin)
• Rods subserve the peripheral vision &
scotopic vision

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• Cones also contain photosensitive
substance

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• Cones responsible for central vision
(photopic) & colour vision
• 120 million rods & 6.5 million cones
• Highest density of cones in fovea

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• Cone density 40 – 45 % greater on nasal
side than temporal side
• Rods are absent at the fovea
• Maximum below the optic disc
• Reduces towards periphery
• More rods in nasal than in the temporal
retina

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RODS CELL
• Each rod 40-60 m long
• Outer segment is cylindrical
• Inner segment thick & consist of two
region –ellipsoid & myoid

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CONE CELL
• Each cone 40-80 micron long
• Largest at fovea
• Shortest at periphery
• Outer segment conical shape contain
iodopsin

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EXTERNAL LIMITING MEMBRANE
• Fenestrated membrane
• Extending from ora serrata to the edge
of optic disc
• ELM is formed by the junction btw the
cell membrane of photoreceptors &
Muller's cells

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OUTER NUCLEAR LAYER
• Formed by nuclei of rods & cones
• Cone nuclei larger than rod nuclei
• Lie in a single layer next to ELM
• Num of rows of nuclei & thickness
varies from region to region

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OUTER PLEXIFORM LAYER
• It consist of connections of rods
spherules and cone pedicles with the
dendrites of bipolar cells and horizontal
cells.
• Thickest at macula-51micro m

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INNER NUCLEAR LAYER
• It consist of cell bodies of bipolar cells
• Consist of cell bodies of horizontal,
amacrine and Muller's cells.

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• Consist of capillaries of central arteries
of retina.
• It is very thin
• This layer is disappear in the fovea

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INNER PLEXIFORM LAYER
• It consist of connection b/w the axons
of bipolar cells, dendrites of ganglion
cells and the process of amacrine cells
• This layer is absent in foveola

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GANGLION CELL LAYER
• It contains the cell bodies & the nuclei
of ganglion cells.

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• Two types
1.midget ganglion cells
2.polysynaptic ganglion cells
• Midget ganglion cell is present in
macular region.
• Polysynaptic ganglion cell is present in
the peripheral retina.

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Contin……..
• Ganglion cell layer is absent in foveola

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NERVE FIBRE LAYER
• Consist of axons of ganglion cells
• It passes through the lamina cribrosa
and become ensheathed by myelin to
the optic nerve

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• Retinal vessels lie in the nerve fibre
layer.
• Nerve fibres varies in thickness from
0.5-2 microns
• Nerve fibre layers are not myelinated.

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INTERNAL LIMITTING MEMBRAIN
• Inner most
• It separates retina from vitreous.
• It is formed by union of terminal
expansions of the mullers fibre.

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• Consist of collagen fibrils, prosteoglycans
of the vitreous, basement membrane &
plasma membrane of the muler’s cells

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Structure of fovea
• No rods & cones
• Other layers are very thin
• Foveola consist of cones & their nuclei
covered by a thin internal limiting
membrane

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• All other layers are absent fovoela
• In the fovea cone axons are arranged
obliquely

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• Outer four layers of retina
pigment epithelium
layer of rods & cone
external limiting membrane
outer nuclear layer get nutrition from
from - choriocapillaris

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• Six inner layers
-outer plexiform layer
-inner nuclear layer
-inner plexiform layer
-layer of ganglion cells
-nerve fibre layer
-internal limiting membrane get
supply from
central retinal artery

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• Outer plexiform layer get supply from
central retinal artery partly & partly
from choriocapillaris
• Fovea supply by choriocapillaris
• Macular region get supply from
superior & inferior temporal branches
of central retinal artery

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