Week 1 Lecture

Question 1

What are some ways in which we can describe a VF loss

Answer 1

• unilateral vs bilateral
• nasal step / arcuate pattern
• horizontal vs vertical midline
• homonymous / heteronymous
• congruous vs incongruous
• macular sparing / splitting

Question 2

What does RNFL defect correspond to?

Answer 2

RNFL defect corresponds to an area of optic nerve where there is damage.
You may see a loss of ganglion cell axonal bundles (figure)

Question 3

What is a common cause of altitudinal VF defect?

Answer 3

Usually due to a vascular incident near the ONH for e,g, AION and BRAO

Question 4

Can ONH Drusen cause a VF defect?

Answer 4

Yes
They produce a stable arcuate VF defect

Question 5

Which fibres cross at the optic chiasm?Th

Answer 5

Nasal fibres cross

Temporal fibres remain ipsilateral

Question 6

What is the Knee of Wilbrand in the optic chiasm?

Answer 6

The Knee of Wilbrand acts as a site where the inferior nasal fibres (anterior knee) bend and also the superior nasal fibres (posterior knee) bend.

Question 7

What is the result of a lesion at the junction of the R ON and optic chiasm

Answer 7

OPtic neuropathy of the RE
Superior temporal defect of the contralateral eye due to the inferior nasal fibres at the knee of Wilbrand.

Vice versa, if there is a ON lesion just anterior to the knee of WIlbrand on the Left side.

End result in a JUNCTIONAL SCOTOMA

Question 8

What are papillomacular nerve bundles?

Answer 8

• Are nasal retinal nerve firbres
• cross at the chiasm (central and posterior chiasm)

Question 9

What is the most common VF defect loss due to a lesion/ defect at the optic chiasm?

Answer 9

Bitemporal VF defect
- most commonly due to ON compression
- e.g. pituitary tumour
- VF loss begins superiorly and extends inferiorly

Question 10

Pattern of VF defect

Answer 10

Question 11

What if there is compressional superior to the chiasm?

Answer 11

Bitemporal hemianopia
Begins inferior and extends superiorly
Due to craniopharyngioma

Question 12

Lesions at the LGN are due to?

Answer 12

Vascular supply defects and depending whether the PCA or ACA (posterior/anterior choroidal artery) is involved, it can produce scotomas with or without macular sparring.

The PCA corresponds to the macula.

The VF defects are always homonymous and incongrous

Question 13

How many fibre bundles is the optic radiation composed of?

Answer 13

Three
Posterior (superior) - parietal lobe to visual cortex (V1).
Contralateral superior retinal fibres (inferior field)

Central (medial) - input from macula

Anterior (inferior) - lateral through the Myers Loop (temporal lobe) to V1
Input from the contralateral inferior retinal fibres (superior field)

Question 14

What causes a “Pie in the sky” VF defect

Answer 14

Temporal lobe affected (Myers Loop)
Caused by lobe inflammation,, tumour and stroke

Question 15

Cause of “Pie on the floor”

Answer 15

contralateral loss compared to location of lesion
Parietal lobe affected

Question 16

Do defects become more congruous or incongruous the further posterior you go?

Answer 16

Defects become more congruous

Question 17

VF defect affecting the occipital lobe are?

Answer 17

Bilateral, congruous and may have macular sparing

Question 18

Summary of diagnosing VF defect

Answer 18

Question 19

Which is the glaucomatous eye?

Answer 19

Right hand side
Extensive cupping is seen with death of ganglion cells

Question 20

The Intraocular region of the ON is 1.0mm in length and divided into 4 subsection. What are they?

Answer 20

Superficial NFL
Prelaminar region - Nerve fibre and astrocytes
Lamina cribrosa - fenestrated CT, nerve fibres and astrocytes
Retrolaminar region - nerve fibres become increasing myelinated from oligodendrocytes and decreased astrocytes

Question 21

The through pathway is responsible for sending signals from photoreceptors to bipolar cells to Ganglion cells and turn 90 degrees towards the ONH and optic nerve.

True or false

Answer 21

True

Question 22

What modifies the through pathway?

Answer 22

Horizontal and amacrine cells

Question 23

What’s located superiorly to the optic chiasm?

Answer 23

Third ventricle

Question 24

What is located posterior, anterior, inferior and lateral to the optic chiasm?

Answer 24

Anterior:
anterior cerebral arteries & communicating arteries

Posterior:
infundibulum, pituitary glands

Inferior:
Pituitary gland

Lateral:
internal carotid artery

Question 25

The optic nerve sends signals to?

Answer 25

LGN Superior colliculus Pretectum Pulvinar Hypothalamus

Question 26

What is the role of the pretectum?

Answer 26

It receives signals from a group of small-diameter retinal ganglion cells with large receptive fields and is involved with the control of the pupillary light reflex by means of a projection to the Edinger–Westphal nucleus of the oculomotor complex. The pupillary light reflex demonstrates a consensual response primarily resulting from crossed and uncrossed optic nerve fibers that enter each pretectal complex which in turn sends a bilateral projection to the Edinger–Westphal nucleus.

Question 27

Lesions affecting the fibres in the brachium of the superior colliculus results in an?

Answer 27

Afferent pupillary defect, but with intact VF because the projection to the LGN remains intact

Question 28

Where does the different layers of the LGN receive input from?

Answer 28

1, 4 6 --> input from contralateral eye 2, 3, 5 --> ipsilateral eye Konio layers receive from bistratified ganglion cells. It is critical in modulating attention, convergence and mapping of visual field

Question 29

Where does Parvocellular layers receive input from and what does a lesion result in?

Answer 29

input from midget RGC - Red green colour vision - Motion processing for slow targets - High Res VA Lesion - reduced colour perception - poor contrast sensitiivity to high spatial frequency

Question 30

Where does the magnocellular layers receive input from and what does a lesion result in?

Answer 30

input from parasol RGC - luminance contrast - motion perception - centre surround arrangement Lesion: - difficulty with high flicker - reduced contrast for low spatial frequencies

Question 31

The visual cortex has 5 regions. What are they responsible for? and what does the dorsal and ventral pathway convey?

Answer 31

V1 - striate cortex - primary visual cortex V2 to V5 - feed forward, feedback and lateral processing Dorsal: "where" --> motion perception Ventral: "what" --> colour, shape, form

Question 32

What are simple cells in the V1?

Answer 32

- elongated receptive fields - on and off subregions - orientation selectivity - sensitive to edges

Question 33

What are complex cells in the V1?

Answer 33

spatially homogenous receptive fields

Question 34

The primary visual cortex has retinotopic map, columnar organisation of perceived image and processes images through parallel pathway to keep visual pathway anatomically separate. How does it do this?

Answer 34

Question 35

The secondary visual cortex sends strong connections to V3, V4 and V5 but also sends strong feedback connection to V1. What role does it play?

Answer 35

- storage of object recognition memory - short term object memories to long term memories

Question 36

V3 to V5 receive input from V1 and V2 and projects to parietal cortex. What role does it play?

Answer 36

May play a role in the processing of global motion. V4 and V5 are involved in form recognition and perception of motion

Question 37

Blood supply of the visual pathway consists of?

Answer 37

Internal carotid artery Vertebral artery

Question 38

Blood supply of visual cortex

Answer 38

Calcarine artery - branches of posterior cerebral artery Terminal branches of middle cerebral artery and anastamosis between middle and posterior cerebral artery

Question 39

The anterior pituitary gland produces ... hormones. Hormones from the hypothalamus reach the anterior pituitary gland via the ... portal system

Answer 39

The anterior pituitary gland produces six hormones. Hormones from the hypothalamus reach the anterior pituitary gland via the hypophyseal portal system.

Question 40

What is the role of the posterior pituitary gland?

Answer 40

It stores hormones produced by hypothalamus. Oxytocin and ADH from the hypothalamus reach the axon terminals of the posterior pituitary. These hormones are released from the axon terminal into the blood stream when they receive signals from the hormone producing hypothalamic neurons

Question 41

What are some of the hormones released by the anterior pituitary gland and posterior pituitary gland.

Answer 41

Anterior: - LH, FSH, TSH, PRL, GH, ACTH Posterior: - ADH, OT

Question 42

What are the different types of pituitary adenomas?

Answer 42

Proloactinomas - 32-66% - most common in women of childbearing age - amenorrhea, loss of libido Non-functioning adenomas (older adults) 14-55% Growth hormone producing adenoma - 8-16% Gigantism ACTH producing adenoma 2-6% Cushing syndrome

Question 43

How does anatomical variation in positioning of pituitary gland affect chiasmatic lesion?

Answer 43

Question 44

What causes a superior bitemporal quadrantanopia?

Answer 44

lesion affecting the inferonasal nerve fibres

Question 45

what causes a junctional scotoma?

Answer 45

Lesion at the anterior knee of Wilbrand

Question 46

What causes a central bitemporal hemianopia?

Answer 46

Lesion at the optic chiasm affecting the nasal macular fibres.

Question 47

What causes an incongruous left homonymous hemianopia

Answer 47

Lesion at the posterior knee of wilbrand in the Right side

Question 48

How does a hemifield slide come about? Hemifield slide: diplopia without oculomotor involvement

Answer 48

This syndrome arises when the eyes no longer share an area of visual field, leading to a loss of binocular fusion in a patient with pre-existing phoria

Question 49

Can a binasal GCL loss be seen before VF defect?

Answer 49

Yes Binasal ganglion cell loss is typical and could be seen with minimal or no detectable VF loss. Thinning may be seen before RNFL loss in some patients. After decompression, some patients show improvement to VF despite persistent GCL loss

Question 50

WHat constitutes a neurological workup of patients?

Answer 50

VA Colour OMS Pupils VF Optic disc appearance OCT