by :Dr. Dhwani Maheshwari 2nd year resident SSG hospital

1. By:Dhwani Maheshwari
2nd year resident
Dept. of Ophthalmology

2. Retina
• Retina, is the innermost tunic of the
eyeball
• Thin,delicate,transparent
membrane
• Highly developed tissue of the eye
• Appears purplish red

3. EMBRYOLOGY OF RETINA
 Retina is developed from the two walls of the optic
cup, namely: (a) nervous retina from the inner wall,
and (b) pigment epithelium from the outer wall
(a) Nervous retina The inner wall of the optic cup is
a single-layered epithelium.
 It divides into several layers of cells which
differentiates further.

4.  (b): Outer pigment epithelial layer. Cells of the outer
wall of the optic cup become pigmented.
 Its posterior part forms the pigmented epithelium of
retina and the anterior part continues forward in ciliary
body and iris..

7. GROSS ANATOMY
Three distinct regions of retina:
1.optic disc
2.macula lutea
3.peripheral retina
retina extends from optic disc to
ora serrata
Surface area:266 mm²

8. Optic disc
 Palepink in colour; well
defined circulararea
 Diameter: 1.5mm
 All the retina layers
terminate here,exceptthe
nerve fibre which pass
through the lamina cribrosa
to run into the optic nerve.
 In contrast to the rest of the
retina,the optic disc appears
pale due to lamina cribrosa,
medullated nerve fibres
behind it & absence of
vascular choroid.

9. MACULA
 Themacula lutea iscomparatively darkarea
 5.5 mm in diameter , situated at the posterior pole of the
eyeball, temporal to optic disc
 Alsocalled asyellow spot or areacentralis
 Primary function :- photoptic vision
 Oxygenated carotenoids, in particular lutein &
zeaxanthin,accumulate within the central macula & cause
yellow colour. They have antioxidants properties & also
function to filter the blue wavelengths of light ,possibly
preventing photic damage.

10.  Foveacentralis is
central depression in
macula;measuring 1.50
mm in diameter & 1.55
mm thickness
 It ismost sensitive part of
retina
 It is entirely made up of
cones.
fovea
Foveola

11. Foveola
 Diameter:- 0.35mm
 Central floor offovea
 Umbo isthe tiny depression
in centre of foveola
macula
FOVEA
FOVEOLA
UMBO

12.  APPLIED;
• Lack of blood vessels and neural tissue in
foveola allows light to pass unobstructed into the
photoreceptor outer segment
• Chronic retinal oedema may result in the deposition
of hard exudates around the fovea in the layer of
Henle with a macular star configuration

13.  UMBO : it corresponds to visible foveolar reflex,seen in
most normal eyes.
 Loss of the FR may be an early sign of damage.
 Greatest concentration of cones is found in the umbo, 150-
200µm diameter known as central bouquet of cones.
 FOVEALAVASCULAR ZONE; It is located inside fovea
but outside foveola,its location can be determined
accurately only by fluorescin angiography.

14.  PARAFOVEA- refers to a
belt that measures 0.5mm in
width & surrounds the
foveal margin.
 PERIFOVEA-refers to
1.5mm belt surrounding
perifoveal region.
 Histologically ,it has several
layers of ganglion cells & 6
layers of bipolar cells.

15. Peripheral retina
 Theperipheral retina canbe divided intofour regions
1. Nearperiphery
2. mid periphery
3. Farperiphery
4. Extremeperiphery

16.  PR is divide into four
parts
 1. Near periphery
• (1.5mm around the
macula )
 2.Mid-periphery
• (3mm around the near
periphery )
• 3.Far periphery;
Extends 9-10 mm
from optic disc on
 the temporal side and
• 16 mm on the
nasal side in the
horizontal
meridian
9-10mm
macula
5.5m
m
16mm
1.5mm
3mm

17. EXTREME PERIPHERY-refers to the
area of ora serrata & pars plana
 ORA SERRATA-
Description Length
Width of ora serrata 2.1mm temporally
0.7-0.8mm nasallly
Location from limbus 6mm nasally
7mm temporally
From equator 6-8mm
From optic disc 25 mm nasally

18.  APPLIED:
 Ora serrata is a watershed zone between ant. & post.
Vascular systems hence peripheral retinal
degenerations are most common

19. 1. Retinal pigment epithelium
2. Layerof rods andcones
3. External limiting membrane
4. Outer nuclear layer
5. Outer molecular (plexiform)layer
6. Inner nuclear layer
7. Inner molecular (plexiform)layer
8. Ganglion cell layer
9. Nerve fibre layer
10. Internal limiting membrane
Microscopic structure of theretina
(from without inward)

20. RETINAL PIGMIENT EPITHELIUM
 It isthe outermost layer ofretina
 Made up of single layer ofhexagonal cells
 Thecells contain pigments
 It isfirmly adherent to the underlying bruch’s layer &
loosely attached layer to layer of rod and cone cells
 Sub-retinal space:- potential spacebetween RPE &
retina

21. • 4- 6 million RPE cells per
eye.
• Extends from the optic disc
to the ora serrata,
Bruch’s
membrane
RPE
Photorecep
tor layers

22.  RPE are Cuboidal cells with three Cell Surfaces characteristics
 1.Apical surface –inner surface
2.Paracellular surface/intercellular
surfaces
3.Basal surface –outer surface
 Apical surface
• Has microvillous processes-
Increases Surface area
• Interdigitate with outer segments of
photoreceptor cells
• Contains melanin granules –more in
macular region
RPE- ULTRA STRUCTURE

23.  APPLIED;
• No specialized junctional complex between RPE and
photoreceptors- they are loosely adhered
• Creates potential space( subretinal space- prone for
RD)& the fluid between these two layers is called
subretinal fluid

24.  Basal surface;
• Attached to its basal
lamina, of Bruch's
membrane.
• Nutrients from
choriocapillaries
diffusess to RPE
through basal lamina
• It has convoluted
infolds to increase
the surface area for
absorption &
secretion of material.
Paracellular surface;
• Contains tight junction( Zonula Occluden
& adheran, gap junctions)
• Junctional complex form blood-retinal
barrier
• Maintains retinal homeostasis and prevents
from toxic damages

25. FUNCTIONS OF RPE:
• Visual pigment regeneration
• Phagocytosis of shed photoreceptor outer-segment discs
• Transport of necessary nutrients and ions to photoreceptor
cells and
 Removal of waste products from photoreceptors
• Absorption of scattered and out-of-focus light via pigmentation
• Adhesion of the retina
• Synthesis and remodeling of the interphotoreceptor matrix,
• Formation of the blood-retina barrier,
• Elaboration of humoral and growth factors.

26.  APPLIED:
• Failure of the RPE to process cellular debris associated
with outer segment turnover cause deposition of Drusen
in ARMD
• Disruption of blood retinal barriers causes retinal edema
eg. Macular edema

27. Layerof Rods& Conecells
 Rods& conestransform light energy intonerve
impulses.

28. RODS CONES
 maximum density in
20°(3mm) from the
fovea.(160,000 rods/mm2)
 minimum density- fovea
 Rodscontain photosensitive
substancerhodopsin
 Night vision- scotoptic
 3 types of iodopsin
trichromatic pigments:
1. S wavelength cones- 440nm
blue light)
2.M wavelenght cone- 540nm
green
3. L wavelenght cone- 577nm
red
 - density is maximum at
fovea (199 000 cones/mm2)
 minimum density- periphery
 conescontain photosensitive
substance iodopsin
 - photopticvision
 rhodopsin is sensitive to
blue-green light- 493nm

29.  APPLIED:
• Mutation of rhodopsin in retinitis pigmentosa causes
maximum pigmentation 3mm around the fovea
• With advanced age there is progressive loss of
photoreceptors (rods are affected more than cone)-
poor night vision in elderly

30. Structure of photoreceptor Rods and cones are composed of several parts- six main parts
1. The outer segment, containing the visual pigment
molecules for the conversion of light into a neural signal;
2. A connecting stalk, the cilium(cytoplasmic isthmus)
3. The inner segment, containing the metabolic apparatus;
4. The outer fiber;
5. The cell body- forms outer nucleated layers
 6.The inner fiber, which ends in a synaptic terminal
outer plexiform layer

32. STRUCTURE OF ROD CELL:
1. 40-60 µm long.
2. Outer segment is cylindrical- contains visual pigments
3. Pigments are located in flattened double lamellae in the
form of discs.
4. Discs various between 600 to 1000/rod cell. There are no
special attachments bet. discs or bet. discs and plasma
membrane.
5. Discs contain 90% of the visual pigment
remaining is scattered on plasma membrane.
6. Inner segment of the rod is thicker than the outer. It has
two regions.
a. Outer eosinophilic ellipsoid which contains
more mitocondria.
b. Myoid which contains glycogen as well as
usual
organelles

33.  Outerrodfibre arisesfrom innerendof rod & passesthrough
external limiting memebrane further swellsinto densely
stainednucleus
 Thenucleusterminates further into innerrod fibre
 Theinner rod fibre endsasabulb calledrod spherule
 APPLIED;
• Rod need great sensitivity to detect the small amount of
light available
• Rod are numerous and contains about a million
rhodopsin molecule in each sac/disc

34. 1. Conical in shape
2. 40 TO 80 µm long
3. Cone at periphery is short(40) but in
central fovea it is tall(80) and resembles
rod
4.Outer segment contains photo pigments
called iodopsin.
5. The cone outer segment have more discs
(1000-1200 per cone) than do rod outer
segments
6. Lamellar disc are attached to the membrane
CONES- MORPHOLOGY

35. 1.Inner segment becomes directly
continuous with the nucleus & lies in the
outer nuclear layer
2. Ellipsoid contains a large number of
mitochondria.
3. Cone inner fibre ends in cone
pedicle/foot which lies in the outer
plexiform layer

36. • Not a true membrane
• Composed of the
junctions(zonulae
adherentes) between
Muller cells and
photoreceptors
 Fenestrated membrane
 Extents from the ora
serrata to the edge of
optic disc.
MULLER
CELL
ONL
ELM
RPE
EXTERNAL LIMITING MEMBRANE

37. OUTER NUCLEAR LAYER
 Made up of the nuclei of rods & cones
 Conenuclei:- 6-7 um
 Rodnuclei :-5.5um
 Thesenuclei lie in asingle layer nextto
external limiting membrane
 Rodnuclei form the bulk of this layer except at cone
dominated fovealregion

38. Variation in Thickness
• Nasalto disc:- 45um ( 8-9 layers)
• Temporal to disc :- 22um (4rows)
• Fovealregion :- 50um (10rows)
• Restof retina except ora serrata – 27 um(1
row of cones & 4 rows of rods)

39. OUTER PLEXIFORM LAYER
 Thislayer ismadeof
synapsesbetween the rod
spherules & conepedicles
with the dendrites of
bipolar cells.
 Also known as Henle’s layer

40. INNER NUCLEAR LAYER
 This layer disappears at fovea & in rest of the retina
consists of the following:
 Bipolar cells
 Horizontalcells
 Amacrinecells
 Somaof Mullers
cells
 Capillaries ofCentral retinal
vessels

41. BIPOLAR CELLS
 Under light microscopy nine types are seen:
 a. Rod bipolar cells(RB)
 b. Invaginating midget bipolar(7) –
 c. Flat midget bipolar
 d. Invaginating diffuse bipolar
 e. Flat diffuse bipolar
 f. On-centre blue cone bipolar
 g. Off-centre blue cone bipolar
 h. Giant bistratified bipolarGBB)
 i. Giant diffuse invaginating bipolar

42.  ROD BIPOLAR CELLS: they
have large soma & profuse
dendrites which arborize only
with the rod sperules.
 MIDGET BIPOLAR CELLS:
 They make contact with cone
pedicle.

43. HORIZONTAL NEURONS
 They are flat cells having numerous horizontal
associative & neuronal interconnections between
photoreceptors & bipolar cells in the outer plexiform
layer

44. AMACRINE CELLS
 These have a pyriform body & a single process which
passes inwards in the inner plexiform layer & forms
connections with the axons of the bipolar cells & the
dendrites & soma of ganglion cells.
 Thus they perform an integrative function.

45. MULLER CELLS
 The nucleus & cell bodies of the muller’s cells are
located within the inner nuclear layer.
 Fibres from their outer end extend upto external
limiting membrane & those from inner end extend
upto inner internal limiting membrane.
 Function:provides structural support
 Aids in metabolism of sensory retina

47. INNER PLEXIFORM LAYER
 Consistsof synapsebetween bipolar cell& dendrites
of ganglioncell
 Absent at fovea

48. GANGLION CELL LAYER
 Consistof cellbody& nucleiof ganglioncell( 2nd orderneurons)
 Absentat fovea
 At the edge of foveola (macula) it is multi layer(6-8
layered) and on temporal side of disc it has two layers.
 Ganglion cells transmits signal from the bipolar cell to the
lateral geniculate body
 Varioustypes of ganglioncell:-
1) W, X ,Y ganglion cell
2) P(P1&P2)& M GANGLIONCELL
3) Off centre & on centre cell
4) Monosynaptic & polysynaptic cell

49. NERVE FIBER LAYER
 The nerve fibre layer contains the
axons of the ganglion cells
 Optic nerve consists of
approximately 1.2- 1.5 million
axons of retinal ganglion cells
 Their course runs parallel to the
retinal
surface
 The fibers proceed to the optic
disc at a right angle, and exit the
eye through the lamina cribrosa as
the optic nerve.
 The fibers generally are
unmyelinated within the retina

50. ARRANGEMENT OF NERVE FIBRES IN THE RETINA
1. Fibres from the nasal half of the
retina come directly to the optic disc
as superior and inferior radiating
fibres (srf and irf).
2. Fibres from the macular region pass
straight in the temporal part of the
disc as papillomacular bundle
(pmb).
3. Fibres from the temporal retina arch
as superior and inferior arcuate
fibres (saf and iaf).

51.  The papillomacular bundle represents the thinnest
portion of the nerve fibre layer around the optic disc

52. ARRANGEMENT OF NERVE FIBRES OF
THE OPTIC
NERVE HEAD:
• Fibres form the peripheral part of the
retina lie deep in the retina but occupy
the most peripheral part of the optic disc.
• While the fibres originating closer to the
optic nerve head lie superficially in the
retina and occupy a more central (deep)
portion of the disc.

53.  THICKNESS OF NERVE FIBRE LAYER AT THE
DISC:
 Thickness of the nerve fibre layer around the
different quadrants of the optic disc margin
progressively increases in the following order:
1.Most lateral quadrant (thinnest)
2.Upper temporal and lower temporal quadrant
3.Most medial quadrant
4.Upper nasal and lower nasal quadrant (thickest)

54. CLINICAL SIGNIFICANCE OF DISTRIBUTION AND
THICKNESS OF
NERVE FIBRES AT THE OPTIC DISC MARGIN:
1. Papilloedema appears first of all in the thickest quadrant
(upper nasal and lower nasal) and last of all in the thinnest
quadrant (most lateral).
2. Arcuate nerve fibres are most sensitive to
glaucomatous damage,
accounting for an early temporal arcuate visual scotoma in
glaucoma
3. Macular fibres occupying the lateral quadrant are most
resistant to glaucomatous damage and explain the retention
of the central vision till end.

55. Internal limiting membrane
• Itformsinterfacebetweenretina&vitreous
• Consistsof followingelements:-
• 1) collagenfibrils
• 2) proteoglycans of vitreous
• 3) basementmembrane
• 4) plasmamembrane of mullercells
• 5) other glialcells

56. Blood supply of retina
• Outer 4 layers :- choriocapillaries
• Inner 6 layer:- central retinalartery
• Fovea:- choriocapillaries
• Macular region:- superior & inferiortemporal
branches of central retinalartery