A 30-year-old patient with a history of syphilis presented with partial vision loss, suggesting a diagnosis of homonymous hemianopia due to an optic tract lesion. The visual pathway involves complex neural connections from the retina to the visual cortex, comprising multiple layers of neurons and synapses. Various causes for lesions in the visual pathway are identified, including optic nerve damage, chiasmal issues, and optic tract lesions, with corresponding diagnostic tests outlined.

1. Visual Pathway

2. Interpret!
 30 year old patient Mr. XYZ , a known case of
Syphilis, presented to Department of
Ophthalmology, NMCH with complaints of partial
loss of vision.What type of visual field defect you
suspect ? Why?

3. What is Visual Pathway?
 Visual pathway or optic pathway is the
nervous pathway that transmits impulses
from retina to visual centre in cerebral
cortex.

8. VISUAL RECEPTORS
 Rods and cones
 They synapse with dendrites of bipolar cells of inner
nuclear layer of the retina.

9. FIRST ORDER NEURONS
 First order neurons (primary neurons) are bipolar
cells in the retina.
 Axons from the bipolar cells synapse with dendrites
of ganglionic cells.

10. SECOND ORDER NEURONS
 They are the ganglionic cells in ganglionic cell
layer of retina.
 Axons of the ganglionic cells form optic nerve.
 Optic nerve leaves the eye and terminates in lateral
geniculate body.

11. THIRD ORDER NEURONS
 They are in the lateral geniculate body.
 Fibres arising from LGB, reaches the visual cortex.

12. OPTIC NERVE
 Formed by the axons of ganglionic cells
 It leaves the eye through optic disc.
 The fibers from temporal part of retina are in lateral
part of the nerve and carry the impulses from nasal
half of visual field of same eye and vice versa.

14. „ OPTIC CHIASMA
 Medial fibers of each optic nerve cross the midline
and join the uncrossed lateral fibers of opposite side,
to form the optic tract.

15. Optic Tract
 Formed by uncrossed fibers of optic nerve on the
same side and crossed fibers of optic nerve from the
opposite side.
 The fibers turn around the peduncle to reach the
lateral geniculate body in thalamus.

16. LATERAL GENICULATE BODY
 Majority of the fibers of optic tract terminate in
lateral geniculate body, which forms the
subcortical center for visual sensation.
 From here, the geniculocalcarine tract or optic
radiation arises.

17. Optic Radiation
 Fibers from lateral geniculate body pass through
internal capsule and form optic radiation.
 The fibers between lateral geniculate body and
visual cortex are also called geniculocalcarine
fibers.
 Optic radiation ends in visual cortex

18. Visual Cortex
 Primary visual area (17) - Perception of visual
impulses
 Secondary visual area (18) - Interpretation of visual
impulses
 Occipital eye field (19) - Movement of eyes.

20. Visual Pathway lesions
 Hemianopia : Blindness over half the field of vision.
 Homonymous : Visual field loss on the same side of
both eyes.

22. Causes of Optic Nerve Lesion
 Optic atrophy
 Traumatic avulsion of the optic nerve
 Indirect optic neuropathy
 Acute optic neuritis

23. Lesions of Chiasma
 Suprasellar aneurysms
 Tumours of pituitary gland
 Third ventricular dilatation due to obstructive
hydrocephalus
 Atheroma of the carotids or posterior
communicating arteries

24. Optic tract lesions
 Syphilitic meningitis
 Tuberculosis and tumours of optic thalamus
 Aneurysms of superior cerebellar or posterior
cerebral arteries.

25. Lesion in Optic Radiation
 Vascular occlusions
 Primary and secondary tumours
 Trauma

26. Homonymous Hemianopia

27. Upper Homonymous Quadrantanopia

28. Lower Homonymous Quadrantanopia

29. INVESTIGATIONS
 FIELD TESTING
1. CONFRONTATION TEST
2. AMSLER GRID
3. PERIMETRY
 MRI (Magnetic Resonance Imaging)
 CT SCAN (Computed Tomography)

30. Interpret!
 30 year old patient Mr. XYZ , a known case of
Syphilis, presented to Department of
Ophthalmology, NMCH with complaints of partial
loss of vision.What type of visual field defect you
suspect ? Why?
 Homonymous hemianopia due to Optic tract lesion

31. Thank you 