The visual pathway begins in the retina and passes through the optic nerves, optic chiasm, and optic tracts to synapse in the lateral geniculate nucleus (LGN). From the LGN, fibers pass through the temporal and parietal lobes to terminate in the occipital lobes in the visual cortex. Lesions in different parts of the visual pathway can cause specific visual field defects, such as lesions of the optic nerve causing complete blindness in the affected eye.

1. vidya

2.  Beginning in the retina, the visual pathway continues
 through the optic nerves,
 optic chiasm,
 and optic tracts to synapse in
 the lateral geniculate nucleus (LGN).
 From the LGN, it extends through
 the temporal and parietal lobes
 to terminate in the occipital lobes

3.  The retina is a thin, multilayered tissue sheet containing
three developmentally distinct, interconnected cell groups
that form signal processing networks:
 • Class 1 :: sensory neuroepithelium (SNE) ::
photoreceptors and BCs
 • Class 2 :: multipolar neurons :: GCs, ACs, and axonal cells
(AxCs)
 • Class 3 :: gliaform neurons :: horizontal cells (HCs)

8. Enlargement of blind spot

9. Altitudinal field defect
 Ischaemic optic neuropathy
 Branch retinal artery occlusion
 Inferior retinal coloboma

10. 10

11. Development of the Optic Nerve:
 Embryonic optic stalk
 Progressively gets
occupied by axons
ganglion cells of retina
 Myelin sheath 
oligodendrocytes
11

12. Parts of Optic Nerve:
47-50 mm in length
Intraocular (1 mm)
Intraorbital (25-30 mm)
Intracanalicular (5-9
mm)
Intracranial (10-16 mm)
12

13. Intra Ocular Part
13

14. 1a-Internal limiting
membrane of
retina
1b-Inner limiting
membrane of
Elschnig
2-Central meniscus
of Kuhnt
3- Spur of
collagenous tissue
separating the
anterior lamina
cribrosa (6) from
the choroid
4-Border tissue of
Jacoby
5- Intermediary
tissue of Kuhnt
7-Posterior lamina
cribrosa
14
Internal limiting membrane of
Elschnig
Central meniscus of Kuhnt
Border
tissue of
Elschnig
Border
Tissue
Of
Jacoby
Intermediat
e
Tissue
Of
Kuhnt

15. INTRA ORBITAL PART:
Anteriorly: Separated from extraocular muscle by orbital fat
Posteriorly: Annulus of Zinn
Laterally: Ciliary ganglion,Division of 3rd nerve, Nasociliary nerve,
Sympathetic plexus, Abducent nerve
Ophthalmic artery
Superior ophthalmic vein cross optic nerve from lateral to medial
Nasociliary nerve
15

16. INTRA CRANIAL PART:
16
Lies above the
cavernous sinus
Optic chiasma is
formed just
above the sellae
Covered by Pia
only

17. 1) LESIONS OF OPTIC NERVE :
Causes:
1. Optic atrophy
2. Indirect optic neuropathy
3. Acute optic neuritis
4. Traumatic avulsion of optic nerve.
Characterised by:
Complete blindness in affected eye with loss of both direct
on ipsilateral & consensual light reflex on contralateral
side.
Near reflex is preserved.
Eg. Right optic nerve
involvement
17

18. Optic chisam
 Floor of the third ventricle.
 5-10 mm above the diphragma sella and the
hypophysis cerebri.
 12mm wide, 8mm A-P , 4 mm thick.
 Important relations: 3rd ventricle, hypothalmus,
pituitary stalk, sella, dorsum sellam anterior and
posterior clinoid processes, cavernous sinus.
 Nasal fibers cross ; temporal fibers do not (53:47).
 Wilband’s knee.

19. Chiasm

21. Location of chiasma
 Central fixation -80%- above the sella
 Pre fixed chiasm-10%-located anteriorly-
so pitutary tumour involves the optic tract
first [lower temporal fields first]
 Post fixed chiasm-10%-located posteriorly-
so optic nerve gets involved first
[upper temporal fields first]

22. Pitutary adenoma
 Visual fields ; bitemporal hemianopia,junctional
scotoma,
bitemporal hemianopic scotoma
 Colour vision; early red deficit
 Visual acuity tends to reduce
 Optic disc- bow tie atrophy rarely papilloedema
 Extraocular movements: cranial nerve palsies,see saw
nystagmus,spasm nutans.

24. Wilbrand’s knee

25. OPTIC TRACT:
* Flattened cylindrical band that
travel posteriolaterally from
angle of chiasma
* Between tuber cinereum and
anterior perforated substance
upto lateral geniculate body.
* Each tract contains
uncrossed temporal
fibres and crossed nasal fibres .
25

26. OPTIC TRACT:
 Macular fibers (crossed
& uncrossed) occupy
dorsolateral aspect of
optic tract
 Upper peripheral fibers
(crossed &
uncrossed)medially
situated
 Lower peripheral
fibers laterally
situated
26

28. OPTIC TRACT
 Carries ipsilateral temporal fibres and
controlateral nasal fibres and pupillary fibres.
 So right optic tract lesion will cause left
homonymous hemianopia

29. ASSOCIATIONS
 Controlateral pyramidal signs.
 Incongruous homonymous hemianopia.
 Wernicke's hemianopic pupil
 Optic atrophy

30. Fibers from optic tract:
30
Superior
Colliculus
Pretectal
nucleus
Dorsal
Lateral
geniculate
nucleus

31. LATERAL GENICULATE BODY:Elevation produced by
lateral geniculate
nucleus in which most
optic tract fibers end
Axons of ganglion cells of
retina synapse with
dendrites of LGB cells
3rd order neurons begins
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32. LATERAL GENICULATE BODYDorsal nucleus
Ventral nucleus (rudimentary)
6 laminae( alternating grey & white
matter)
Axons from the ipsilateral eye –
2, 3, 5
Axons from the contralateral eye - 1, 4,6
32

33. Lateral Geniculate Body: Large magnocellular
neurons (M cells) - 1 and 2
layer-Y ganglion cells
perception of movement, gross
depth, and small differences
in brightness
 Small parvocellular
neurons (P cells)- 3,4,5,6
layer- X ganglion cells
Colour perception, texture
shape & fine depth
 Koniocellular cells(K cells
or interlaminar cells)
Short-wavelength "blue" cones
33

34. LATERAL GENICULATE BODY:
34
Macular fibres - posterior
2/3 of LGB
Upper retinal fibres -
medial half of anterior 1/3
of LGB
Lower retinal fibres -
lateral half of anterior 1/3
of LGB

36. OPTIC RADIATION:
36
Inferior
retinalower
part of optic
radiation
superior retina
upper part of
optic radiation

37. OPTIC RADIATIONS:
Geniculocalcarine
pathway extend from
lateral geniculate body
 visual cortex
MEYERS LOOP(inferior
retinal fibers)-pass
through temporal lobe
looping around
inferior horn of lateral
ventricle
37

39. OPTIC RADIATIONS
 The corresponding retinal elements lie
progressively closer, so congruous
hemianopia.
 Passes through the temporal lobe and pareital
lobe and ends in the visual cortex.

40. TEMPORAL LOBE
 Controlateral congruous homonymous
superior quadrantanopia[pie in the sky]
 Controlateral hemisensory disturbance
 Mild hemiparesis
 Paraxysomal olfactory and uncinate fits.
 Formed visual hallucinations
 Seizures and receptive dysphasia.

41. VISUAL CORTEX(CORTICAL
RETINA):
41
•Impulse from
corresponding 2 points
of retina meet
•Right visual
cortexreceive
impulse left half of
visual field
•Left visual
cortexreceive
impulse from right half
visual field
MACULA posteriorly
PERIPHERAL RETINA anteriorly
UPPER RETINA above calcarine sulcus
LOWER RETINA below the calcarine sulcus

42. Pie in the sky

43. PAREITAL LOBE
 Controlateral congruous homonymous inferior
quadrantanopia[pie on the floor]
 Visual perception difficulties
 Right-left confusion
 Acalculia
 Assymmetric OKN.[OKN response diminished
towards the side of the lesion.]

44. Pie on the floor

45. Visual Cortex:
Striate cortex Extrastriate cortex

45

46. 46
Anterior
Knee of
Von-wille
Brand
Posterio
r
Knee of
Von-
wille
Brand

47. LATERAL GENICULATE BODY:

47
CROSSED FIBERS- 1,4,6
UNCROSSED FIBERS- 2,3,5
CORRESPONDING PART OF 2
RETINA END IN NEIGHBOURING
PART OF ADJACENT LAMINAE
smallest lesion of retina results in
degeneration of 3 laminae of LGB in
which the retinal fiber end
Optic radiation begins from all 6
laminae lesion of visual cortex will
cause degeneration of all 6 laminae

48. TWO STREAM HYPOTHESIS:
 Ventral
48
Ventral
Pathway(parvocellular)

temporal lobe
Dorsal
Pathway(magnocellular
) parietal lobe
Recognistion
&
indentificatio
n
Spatial
location
Visual
agnosia
Visual
neglec
t
Parvocellula
r “what”
pathway
Magnocellula
r
“where”
pathway

50. Striate calcarine cortex
 Congruous homonymous hemianopias
with macular sparing, macular
involvement alone.
 Formed visual hallucinations.
 Anton's syndrome[ denial of blindness]
 Riddoch phenomenon

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