QS Study

Effects of Lesions of the Visual Pathway

Visual Pathway is a pathway over which a visual feeling is transmitted from the retina to the brain. Lesions within the visual pathway produce characteristic visual defects that pinpoint the site of the lesion. A lesion anterior to the optic chiasma results in loss of the visual field to that eye.

Effects of lesions of the visual pathway –

Circumferential blindness: It means blindness of peripheral circumferential area of the affected eye. It occurs due to inflammation to the corresponding optic nerve.

Total blindness of one eye: It follows the complete section of one optic nerve.

Nasal hemianopia: It follows a partial lesion of the optic chiasma on its lateral side.

Bitemporal hentianopia: It follows a sagittal section of the optic chiasma.

Contralateral homonymous hemianopia: It occurs due to the division of the optic tract or optic radiation or destruction of the lateral geniculate body.

Visual Pathway 1

Fig: Effects of Lesions of the Visual Pathway

The visual pathway is –

  • Source of light
  • Light falls on the eye
  • Crosses the conjunctiva & cornea
  • Passes through the other refractive media of the eye
  • Falls on the retina
  • Stimulates the bipolar cells in the inner layers of the retina (1st order neuron)
  • Passes to the ganglionic cells of the retina (2nd order neuron)
  • Optic nerve
  • Optic chiasma
  • Optic tract
  • Lateral geniculate body (3rd order neuron)
  • Optic radiation
  • Visual Cortex.
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