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OPTM5103/5104 > Week 1 Lecture > Flashcards

Week 1 Lecture Flashcards

1
Q

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

A
  • unilateral vs bilateral
  • nasal step / arcuate pattern
  • horizontal vs vertical midline
  • homonymous / heteronymous
  • congruous vs incongruous
  • macular sparing / splitting
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2
Q

What does RNFL defect correspond to?

A

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

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3
Q

What is a common cause of altitudinal VF defect?

A

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

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4
Q

Can ONH Drusen cause a VF defect?

A

Yes
They produce a stable arcuate VF defect

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5
Q

Which fibres cross at the optic chiasm?Th

A

Nasal fibres cross

Temporal fibres remain ipsilateral

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6
Q

What is the Knee of Wilbrand in the optic chiasm?

A

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.

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7
Q

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

A

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

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8
Q

What are papillomacular nerve bundles?

A
  • Are nasal retinal nerve firbres
  • cross at the chiasm (central and posterior chiasm)
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9
Q

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

A

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

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10
Q

Pattern of VF defect

A
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11
Q

What if there is compressional superior to the chiasm?

A

Bitemporal hemianopia
Begins inferior and extends superiorly
Due to craniopharyngioma

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12
Q

Lesions at the LGN are due to?

A

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

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13
Q

How many fibre bundles is the optic radiation composed of?

A

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)

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14
Q

What causes a “Pie in the sky” VF defect

A

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

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15
Q

Cause of “Pie on the floor”

A

contralateral loss compared to location of lesion
Parietal lobe affected

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16
Q

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

A

Defects become more congruous

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17
Q

VF defect affecting the occipital lobe are?

A

Bilateral, congruous and may have macular sparing

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18
Q

Summary of diagnosing VF defect

A
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19
Q

Which is the glaucomatous eye?

A

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

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20
Q

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

A

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

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21
Q

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

A

True

22
Q

What modifies the through pathway?

A

Horizontal and amacrine cells

23
Q

What’s located superiorly to the optic chiasm?

A

Third ventricle

24
Q

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

A

Anterior:
anterior cerebral arteries & communicating arteries

Posterior:
infundibulum, pituitary glands

Inferior:
Pituitary gland

Lateral:
internal carotid artery

25
Q

The optic nerve sends signals to?

A

LGN
Superior colliculus
Pretectum
Pulvinar
Hypothalamus

26
Q

What is the role of the pretectum?

A

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.

27
Q

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

A

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

28
Q

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

A

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

29
Q

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

A

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

30
Q

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

A

input from parasol RGC
- luminance contrast
- motion perception
- centre surround arrangement

Lesion:
- difficulty with high flicker
- reduced contrast for low spatial frequencies

31
Q

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

A

V1 - striate cortex - primary visual cortex
V2 to V5 - feed forward, feedback and lateral processing

Dorsal: “where” –> motion perception
Ventral: “what” –> colour, shape, form

32
Q

What are simple cells in the V1?

A
  • elongated receptive fields
  • on and off subregions
  • orientation selectivity
  • sensitive to edges
33
Q

What are complex cells in the V1?

A

spatially homogenous receptive fields

34
Q

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?

A
35
Q

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?

A
  • storage of object recognition memory
  • short term object memories to long term memories
36
Q

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

A

May play a role in the processing of global motion.

V4 and V5 are involved in form recognition and perception of motion

37
Q

Blood supply of the visual pathway consists of?

A

Internal carotid artery

Vertebral artery

38
Q

Blood supply of visual cortex

A

Calcarine artery - branches of posterior cerebral artery

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

39
Q

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

A

The anterior pituitary gland produces six hormones.

Hormones from the hypothalamus reach the anterior pituitary gland via the hypophyseal portal system.

40
Q

What is the role of the posterior pituitary gland?

A

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

41
Q

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

A

Anterior:
- LH, FSH, TSH, PRL, GH, ACTH

Posterior:
- ADH, OT

42
Q

What are the different types of pituitary adenomas?

A

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

43
Q

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

A
44
Q

What causes a superior bitemporal quadrantanopia?

A

lesion affecting the inferonasal nerve fibres

45
Q

what causes a junctional scotoma?

A

Lesion at the anterior knee of Wilbrand

46
Q

What causes a central bitemporal hemianopia?

A

Lesion at the optic chiasm affecting the nasal macular fibres.

47
Q

What causes an incongruous left homonymous hemianopia

A

Lesion at the posterior knee of wilbrand in the Right side

48
Q

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

A

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

49
Q

Can a binasal GCL loss be seen before VF defect?

A

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

50
Q

WHat constitutes a neurological workup of patients?

A

VA
Colour
OMS
Pupils
VF
Optic disc appearance
OCT

51
Q
A

OPTM5103/5104 (7 decks)

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