anatomy of retina

1. RETINA

2. • Inner nervous coat of eyeball
• FUNDUS
• Thin, transparent membrane
• purplish red in colour
• Formation of optical image
• Thickness- 0.56mm near optic disc to 0.1mm at ora serrata
• Thinnest at centre of fovea

3. EXTENSION
• Outer surface- Bruchs membrane of
choroid
• Inner surface- vitreous
• Posteriorly- optic nerve
• Anteriorly- epithelium of iris and
• ciliary body(ora serrata)
• Ant- extends more on nasal side
• Firmly attached- margins of optic disc
& ora serrata

5. Optic disc
Macula lutea
Peripheral retina
OPTIC DISC
• 1.5mm in diameter & 3mm nasal
to macula
• Pale pinK
• Depression in centre- physiological cup
• Central retinal vessels
• Optic nerve- lamina cribrosa
• Blind spot

6. • MACULA –
• oval,yellowish,at centre of posterior part
• 5mm in diameter & 3mm temporal to optic disc
• carotenoid pigment-xanthophyll(present from outer nuclear layer
onward)
• Central depression – fovea centralis
• Sides of depression – Clivus
• Floor of depression – foveola
• 1,47,000 per sq.mm

7. • Umbo- foveolar reflex
• Central bouquet of cones
• Parafovea-0.5mm surrounding fovea
• Perifovea-1.5mmsurrounding parafovea

8. • Near periphery – 1.5mm ring peripheral to temporal vascular
Arcades
• Equatorial retina- retina around the equator
• Peripheral retina – region anterior to it

9. • OUTER PIGMENTED LAYER
• Retinal pigment epithelium (RPE)
• INNER NEUROSENSORY LAYER
• Photoreceptors
• External limiting membrane
• Outer nuclear layer
• Outer plexiform layer
• Inner nuclear layer
• Inner plexiform layer
• Ganglion cell layer
• Nerve fibre layer
• Internal limiting membrane

10. • LAYERS OF RETINA

11. • EMRYOLOGICAL DEVELOPMENT
• Outer pigmented layer- outer layer of optic cup
• Neurosensory layer- inner layer of optic cup
• anterior one fifth- columnar
• Posterior four fifth
• outer nuclear zone & inner marginal zone
• Inner neuroblastic layer –ganglion cells,amacrine cells,Muller cells
• Outer neuroblastic layer –rods,cones,bipolar cells
• Macular area- superimposed nuclei of ganglion cell layer, lateral to optic disc

12. • DEVELOPMENT

13. • RETINAL PIGMENTED EPITHELIUM
• Single layer of hexagonal cells
• Narrow & tall Posteriorly ,flattened near ora serrata
• Apical end- microvilli – project between outer segment of rods & cone
• Embedded in glycosaminoglycans
• Cell nucei- basal part
• Melanin granules
• Basal region- zona adherens,apical region- zona occludens

14. • FUNCTION
• Absorption of light
• Turn over of outer segment of rods& cones
• Formation of rhodopsin& iodopsin( vitamin A)
• SUB RETINAL SPACE
• - Retinal detachment
• Ocular albinism
• -transillumination of iris

15. NEURAL RETINA
• PHOTO RECEPTORS
• BIPOLAR CELLS
• GANGLION CELLS

16. • PHOTORECEPTORS
• RODS
• 110 to 125 million
• Rhodopsin- scotopic vision
• 40to 60micrometre long
• STRUCTURE
• Outer segment – cylindrical & contains lamellar disc
• Eccentric cilium- 9 doublet microtubules with no Central pair
• Inner segment – ellipsoid& myoid
• Ellipsoid (outer segment) – mitochondria
• Myoid- (inner segment- ER,Golgi apparatus,ribosomes

17. • Outer rod fibre
• Rod granule( cell body with nucleus)
• Inner rod fibre
• Rod spherule

18. • CONES
• 6.3 to 6.8 million
• Iodopsin, scotopic vision
• 65to 75micrometre long
• Outer segment – conical,wider base &
• rounded tip
• Continuous with extra cellular space
• Cilium
• Inner segment – ellipsoid ( very plump)& myoid
• Cell body with nucleus
• Inner cone fibre
• Cone pedicle

19. BIPOLAR CELLS
• First order neurons (neurons in posterior root ganglion)
• Rod bipolar cells several rod cells to 1to 4 ganglion cells
• Flat or diffuse bipolar cells –many cone cells with many ganglion cells
• Midget bipolar cell- single cone cell with single midget ganglion cell

20. • GANGLION CELLS
• Second order neuron-nervous ganglion)
• Increases from periphery to macula(10 layers)
• Fovea- absent
• HORIZONTAL CELLS
• Associated with cones- 7
• Associateed with rods – 10 to 12
AMACRINE CELLS
No axons,large cell body,abundant cytoplasm,lobulated nuclei
Synapse with dendrites of ganglion cells& axons of bipolar cells

21. • Supporting cells- MULLER CELL
• Fill in most of the space of neural retina,not occupied by neurons
• On outer surface – row of zona adherents between photoreceptor cell&
radial process of Muller cells- OUTER LIMITING MEMBRANE
• On inner surface –muller cells have expanded termination covered by
basement membrane – INNER LIMITING MEMBRANE
•

22. • BLOOD SUPPLY
• Outer 4 layers-
chorio capillaries
• Inner 6 layers-
• Central retinal artery & vein
• Course of Central retinal
artery
• circle of zinn or Haller

23. • Arterial branches run in nerve fibre layer
• Foveal avascular zone- 500micronmetre in diameter
• BLOOD RETINAL BARRIER
• Tight junctions of RPE
• Nonfenestrated endothelium of capillaries
• CENTRAL RETINAL VEIN
• Accompany CRA& leaves through lamina cribrosa
• Lie on lateral side of artery in optic nerve
• Longer course in subarachnoid space
• Drains into cavernous sinus or superior ophthalmic vein

24. • ARRANGEMENT OF NERVE FIBRES IN RETINA

25. • THICKNESS OF NERVE FIBRE LAYER AT DISC
• Most lateral quadrant(thinnest)
• Upper and lower temporal quadrant
• Most medial quadrant
• Upper and lower nasal quadrant( thickest)
• CLINICAL SIGNIFANCE
• Papilledema- first in thickest quadrant
• Glaucomatous damage- arcuate fibres(more sensitive)
. Macular fibres(resistant)

26. CONGENITAL ANAMOLIES
• Medullated nerve fibres

27. • COLOBOMA of optic disc-
• Failure of closure of embryonic fissure
• Minor defect or fully developed coloboma
• HYPOPLASIA of optic disc
• Small disc surrounded by yellowish ring- double ring sign
• PERSISTENT HYALOID ARTERY
• Bregmesters papillae
• Mittendorf dot

29. • DRUSEN of optic disc
• Intracapillary refractile bodies
• Children- present as pseudopapilledema
• Adults- waxy pea like irregular refractilebodies