This document provides an overview of the anatomy and physiology of the retina. It begins with an introduction and index, then covers the following topics in detail: anatomy, blood supply, photochemistry, and physiology of the retina. The anatomy section describes the layers of the retina, including the retinal pigmented epithelium, rods and cones, nerve fibers and more. It also outlines dimensions of the macula and fovea. The document provides a thorough review of the structure and function of the retina.

2. INDEX
 INTRODUCTION (AVINASH)
 ANATOMY ( MANUJA)
 BLOOD SUPPLY (RAKESH)
 PHOTOCHEMISTRY ( SHWETHA AND
AVINASH)
 PHYSIOLOGY (AVINASH)

3. INTRODUCTION
 Retina is multi-layered sensory tissue that
lines the back of eye.
 It contains millions of photoreceptors that
capture light rays and convert them into
electrical impulses.
 These impulses travel along the optic nerve
to the brain where they are turned to
images.

5. HOW EYE WORKS
• Light rays enter the eye through the clear cornea,
pupil and lens.
• These light rays are focused directly onto the retina,
the light sensitive tissue lining the back of the eye.
• The retina converts light rays into impulses; sent
through the optic nerve to your brain, where they
are recognized as images.

7. WHAT HAPPENS IN RETINA
• Converts light energy into neural signal.
• Contains first three cells of visual pathway
3. photoreceptor-converts photon to neural signal
through phototransduction and pass signal to bipolar
cell.
4. Bipolar cells – it synapse with ganglion cells.
5. ganglion cells – it transmits signal from eye.
• Other cells like horizontal cells, amacrine cells, and
interplexiform neurons modify and integrate the signal
before it leaves the eye.

8. DIMENSIONS OF RETINA
 2.1mm temporally , 0.7-0.8mm
nasally.
 The total surface area of retina is
266mm square.

9. OPTIC DISC
 pale pink in colour, circular in
shape.
 photo receptors are absent.
 known as Blind spot.

10. MACULA
known as yellow spot.
elliptical in shape.
diameter is 5.5mm.
responsible for central vision

12. FOVEA
It is the most sensitive part of the Retina.
Its diameter is 1.85mm .
It has 5 degree of visual field.
thickness is 0.25mm.

14. ORA SERRATA
 It is the last region where the
retina ends and ciliary body starts.
 consist of tooth like projection .
 Retina is attached both to the
vitreous &retinal pigmented
epithelium.

15. ANATOMY OF RETINA

16. LAYERS OF RETINA
 Retinal pigmented epithelium
 Layers of rods and cones
 External limiting membrane
 Outer nuclear layer
 Outer molecular layer
 Inner nuclear layer
 Inner molecular layer
 Ganglion cell layer
 Nerve fibre layer
 Internal limiting menbrane

17. LAYERS OF RETINA
 RETINAL PIGMENTED EPITHELIUM
• Outermost layer
• Consist of Single layer of hexagonal
• It is Loosely attached to the layers of rods
&cones
• The potential space between RPE &the sensory
retina is called subretinal space filled with
subretinal fluia

18. LAYERS OF RETINA
 LAYERS OF ROD AND CONES
ROD
contains rhodopsin as a photosensitive
substances.
helps in vision of low illumination.
120 million in number,absent in fovea
CONES
helps in phototopic vision
6.5 million in number,highest in fovea

20. LAYERS OF RETINA
 EXTERNAL LIMITING MEMBRANE
• layer that separate the inner segment
portions of the photoreceptors from their cell
nucleus.
 OUTER NUCLEAR LAYER
• this layer contains the rod and cell bodies.
• the cone cell body and nucleus are larger.

22. LAYERS OF RETINA
 OUTER PLEXIFORM LAYER
• projections of rod and cones ending in the rod
spherule and cone pedicle respectively.
• these make synapses with dendrites of bipolar
in the macular region also known as fiber layer
of henle.

23. LAYERS OF RETINA
 INNER NUCLEAR LAYER
• consist of the cell bodies of horizontal
cells,bipolar cells,amacrine cells,interplexiform
neurons.
 INNER PLEXIFORM LAYER
• Cointains the synapse between the bipolar cell
axon and the dendrites of the ganglion and
amacrine cells.

24. LAYERS OF RETINA
 GANGLION CELL LAYER
• contains nuclei of ganglion cells, the axons
of which become the optic nerve fibres for
messages.
 NERVE FIBRE LAYER
• Consist of ganglion cell axon.
 INNER LIMITING MEMBRANE
• Innermost boundary
• Composed of muller cells.

25. BLOOD SUPPLY OF RETINA
 Four layers RPE,layers of rod and
cones,external limiting membrane,outer
nuclear layer gets blood supply from
choriocapillaries.
 The rest six layers gets from central retinal
artery.
 Fovea is avascular but partially gets blood
supply from choriocapillaries.
 Macular area gets from central retinal artery
and cilioretinal artery.

26. PHOTOCHEMISTRY OF VISION
 VITAMIN A AND VISUAL PIGMENTS
• dietary sources of retinol for human is animal
and plant food.
• animal food contains retinol but plant do
not.
• carotenes in plant food is converted to
retinol by metabolic activity of small
intestine.

28. PHOTOCHEMISTRY OF VISION
ABSORPTION AND STORAGE
 In intestine, Vit A is esterified and reaches the
blood stream.
 Retinol from the blood stream is transported
to the liver.
 Retinol becomes bound with retinol binding
protein.
 The retinol protein complex enters the
circulation and reaches the target tissues
 In retina it becomes attached to the basal
surfaces of the RPE cells.

29. PHOTOCHEMISTRY OF VISION
 VISUAL PIGMENTS
• RHODOPSIN
photosensitive pigment,present in outer
segment of disc of rod, contain protein
called opsin,insoluble in water,sensitive to
heat and chemical agents.
• PHOTOPSIN
different from rod,responsible for central
and colour vision.

30. PHYSIOLOGY OF VISION
 INITIATION OF VISION
 PROCESSING AND TRANSMISSION OF
VISUAL SENSTAION
 VISUAL PERCEPTION

31. INITIATION OF VISION
 Also known as phototransduction.
 The whole phenomenon of conversion of
light energy into nerve impulse is known as
phototransduction.
 Photochemical changes take place .

32. RHODOPSIN BLEACHING
 Rhodopsin refers to the visual pigment
present in the rods – the receptors for
night(scotopic) vision.
 Its maximum absorption spectrum is around
500 nm.
 Rhodopsin consists of a colourless protein
called opsin coupled with a carotenoid called
retinine

33. RHODOPSIN BLEACHING
 Light falling on the rods converts 11-cis-
retinal componentof rhodopsin into all-trans-
retinal through various stages .
 The all trans-retinal so formed is soon
separated from the opsin.
 This process of separation is called
photodecomposition.
 Rhodopsin is said to be bleached by the
action of light.

35. RHODOPSIN REGENERATION
 The 11-cis-retinal is regenerated from the all-
trans-retinal separated from the opsin and
vitamin-A supplied from the blood.
 The 11-cis-retinal then reunits with opsin in the
rod outer segment to form the rhodopsin. This
whole process is called rhodopsin regeneration
 The bleaching occurs under the influence of
light,whereas the regeneration process is
independent of light.

37. VISUAL CYCLE
 In the retina of living animals, under constant
light stimulation, a steady state must exist
under which the rate at which are bleached is
equal to the rate at which they are
regenerated. This equilibrium between the
photodecomposition and regeneration of
visual pigmentsis referred to VISUAL CYCLE.

38. QUESTTIONS ?????

39. THANK YOU