Visual Field Deficits

Core principial of visual fields

- each cerebreal hemisphere processes the opposite visual field

- R brain processes L field

- L brain processes R field

visual fields due to

partial decussation at optic chiasm

Retinal Mapping

- nasal retina maps temporal field

- temporal retina maps nasal field

image inversion due to

cornea and lens refraction

Optic Nerve Lesions: Presentation

monocular blindness due to afferent signal loss

Optic Nerve Lesions: Causes

- optic neuritis

- compression

- ischemia

Optic Chiasm Pathophysiology: Presentation

- crossing nasal fibers affected

- bitemporal hemianopia

Optic Chiasm Pathophysiology: Common Causes

- pituitary adenoma

- craniopharyngioma

Optic Tract Pathophysiology: Presentation

- each tract carries contralateral visual field

- lesions cause homonymous visual deficits

Optic Tract Pathophysiology: Possible Causes

- CVA (most commonly PCA)

- Tumors

- Demyelinating disease (MS)

- TBI

Meyers Loop Lesion: Presentation

- carries superior visual field

- contralateral superior quadrantanopia

- "pie in the sky"

Meyers Loop Lesion: Common Causes

- Temporal lobe CVA

- Temporal lobe tumor

Parietal Radiation Lesion: Presentation

- carries inferior visual field

- contralateral inferior quadrantanopia

- "pie on the floor"

Parietal Radiation Lesion: Common Causes

- CVA (MCA common)

- Parietal tumors

- TBI

Occipital Cortex Lesion: Presentation

- homonymous hemianopia

- macular sparing due to dual vascular supply and cortical magnification

Occipital Cortex Lesion: Common Causes

- CVA (PCA most common)

- Occipital Tumors

- TBI

Neurovascular Correlation: PCA

homonymous hemianopia

Neurovascular Correlation: MCA temporal

superior quadrantanopia

Neurovascular Correlation: MCA parietal

inferior quadrantanopia