👁️ Special Senses🟡 High-yieldVisual Pathways

Visual Field Defects

The patterns of lost vision that follow damage at different points along the visual pathway, used to locate the problem.

Key points

The visual pathway runs from the retina through the optic nerve, the optic chiasm and the optic tract to the back of the brain.
Damage to one optic nerve causes loss of vision in that whole eye.
Pressure at the optic chiasm, as from a pituitary tumour, cuts the outer (temporal) halves of both fields, called bitemporal hemianopia.
Damage behind the chiasm causes loss of the same-side half of the field in both eyes, called homonymous hemianopia.
So the pattern of field loss points precisely to where along the pathway the damage lies.

Memory trick

Field defects localise the lesion: one optic nerve means that eye is blind; the chiasm (pituitary tumour) gives bitemporal hemianopia; behind the chiasm gives homonymous hemianopia.

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👁️ Special Senses🟡 High-yieldVisual Pathways

Visual Field Defects

The patterns of lost vision that follow damage at different points along the visual pathway, used to locate the problem.

Key points

The visual pathway runs from the retina through the optic nerve, the optic chiasm and the optic tract to the back of the brain.
Damage to one optic nerve causes loss of vision in that whole eye.
Pressure at the optic chiasm, as from a pituitary tumour, cuts the outer (temporal) halves of both fields, called bitemporal hemianopia.
Damage behind the chiasm causes loss of the same-side half of the field in both eyes, called homonymous hemianopia.
So the pattern of field loss points precisely to where along the pathway the damage lies.

Memory trick

Field defects localise the lesion: one optic nerve means that eye is blind; the chiasm (pituitary tumour) gives bitemporal hemianopia; behind the chiasm gives homonymous hemianopia.

All of Ophthalmology More Special Senses