visual pathway and field defects

Question 1

What are the central fibers of the optic nerve responsible for?

Answer 1

Visual processing and transmission from macula of the retina to the brain

Central fibers play a critical role in visual perception.

Question 2

What does ‘heteronymous’ refer to in visual field defects?

Answer 2

Visual field defects from different sides of the opposite visual fields

This indicates that the defects occur in non-corresponding parts of the visual field.

Question 3

What are the earliest visual field defects associated with optic nerve lesions?

Answer 3

Ipsilateral central scotoma and unilateral anopia

These defects indicate damage to the optic nerve, affecting visual perception.

Question 4

Which fibers are most susceptible to ischemia in optic nerve diseases?

Answer 4

Macular/central fibers

These fibers are typically affected first in any optic nerve disease.

Question 5

What is the visual field defect associated with optic chiasma lesions?

Answer 5

Bitemporal hemianopia
or
heteronymous hemianopia
## Footnote

This defect occurs due to compression of the crossing fibers at the chiasm.

Question 6

List some causes of bitemporal hemianopia.

Answer 6

• 3rd ventricular glioma
• Pituitary adenoma
• Craniopharyngioma
• Anterior communicating artery aneurysm
• Cavernous sinus thrombosis

These conditions can lead to compression of the optic chiasm.

Question 7

What visual field defect is associated with pituitary adenoma?

Answer 7

Bitemporal superior quadrantanopia

This occurs due to the adenoma compressing the nasal fibers of the optic chiasm.

Question 8

What is the earliest visual field defect in craniopharyngioma?

Answer 8

Bitemporal inferior quadrantanopia which later on develops to bitemporal/heteronymous hemianopia

This defect arises from compression of the optic chiasm by the tumor.

Question 9

What is a junctional scotoma?

Answer 9

cutting of I/L temporal + I/L nasal + C/L inferonasal fibres

This defect can occur at the junction of the optic nerve and optic chiasm.

Question 10

What type of visual loss is associated with lesions at the junction of optic nerve and optic chiasm?

Answer 10

Junctional scotoma

This involves a specific pattern of visual field loss affecting certain quadrants.

Question 11

What is the significance of the lesion at lateral optic chiasma?

Answer 11

It is always associated with binasal hemianopia

temporal fibres from both side get cut

Question 12

What does c/L homonymous hemianopia indicate?

Answer 12

lesion at OT , LGB , OR
## Footnote
🌛. 🌛

Question 13

What are the visual field defects associated with temporal lobe disease?

Answer 13

Uncinate fits, seizures, and visual hallucinations.

pie in the sky / homonymous superior quadrantanopia

Question 14

What characterizes a complete occipital lobe lesion?

Answer 14

C/L homonymous hemianopia, which is rare.

This condition results from significant damage to the visual processing areas in the occipital lobe.

Question 15

What is the result of a lesion in the tip of the occipital cortex?

Answer 15

C/L homonymous macular defect aka cookie cutter defect

Question 16

What are the features of parietal lobe disease?

Answer 16

• Aphasia
• Acalculia
• Agraphia
• Apraxia (if non-dominant lobe involved)

pie on the floor or homonymous inferior quadrantanopi

Question 17

What is the term for the visual field defect known as ‘Pie on the floor’?

Answer 17

C/L homonymous inferior quadrantanopia.

This term describes a specific pattern of visual field loss associated with lesions affecting the lower visual field.

Question 18

What is the role of the posterior cerebral artery?

Answer 18

It supplies blood to the occipital lobe and visual cortex except the tip of the lobe

The health and function of the posterior cerebral artery are critical for maintaining visual integrity.

Question 19

What is ‘Cookie cutter defect’ in relation to visual field loss?

Answer 19

Macular defect due to a middle cerebral artery lesion.

This defect specifically affects the central vision area and has a distinct presentation.

Question 20

True or False: Lesions in the occipital lobe can depend upon the arteries supplying them.

Answer 20

True.

The vascular supply is crucial for the integrity of visual pathways and their associated functions.

Question 21

Fill in the blank: The visual pathway includes _______ radiation.

Answer 21

[optic radiation].

This term refers to the pathways that transmit visual information from the lateral geniculate body to the visual cortex.

Question 22

What is Weinke’s pupil associated with?

Answer 22

lesions in optic tract

It presents bilaterally and can indicate specific neurological conditions.

Question 23

What is a key characteristic of LG B Lesion?

Answer 23

incongrous with normal pupil and optic atrophy

Question 24

What do c/L fibres in LG B Lesion relay into?

Answer 24

Laminae 1, 4, 6

These fibres are critical for relaying information to the appropriate cortical areas.

Question 25

What do I/L fibres in LG B Lesion relay into?

Answer 25

Laminae 2, 3, 5 ## Footnote These fibres handle different aspects of visual processing.

Question 26

What does incomplete LGB lesion cause ?

Answer 26

Keyhole VFD ## Footnote This type of visual field defect has specific clinical implications.

Question 27

What does altitudinal VFD respect?

Answer 27

Horizontal midline ## Footnote This type of visual field defect can indicate specific ocular or neurological issues.

Question 28

What mnemonic can be used to remember the causes of B/L superior altitudinal VFD?

Answer 28

GOA: Glaucoma, Optic disc Drusen, AION ## Footnote These conditions are known to affect visual fields in specific patterns.

Question 29

What are the causes of central scotoma?

Answer 29

* Any ON lesion * Optic neuritis * Toxic optic neuropathy * Hereditary optic neuropathy * Cone dystrophy ## Footnote Central scotoma can arise from various optic nerve pathologies.

Question 30

What is Anton's syndrome?

Answer 30

Denial of blindness ## Footnote Patients may insist they can see despite having cortical blindness.

Question 31

What is the Riddoch phenomenon?

Answer 31

Statokinetic dissociation ## Footnote This phenomenon involves the ability to perceive moving objects but not stationary ones.

Question 32

What is the use of VEP ?

Answer 32

differentiate btwn functional and organic blindness ## Footnote used for detecting malingering and hysterical blindness