Clinical Skills 4 - D - Visual field defects and examination

Question 1

Where does vision from the temporal visual field and nasal visual field hit the retina?

Answer 1

Temporal visual field - hits the nasal retina Nasal visual field - hits the temporal retina

Question 2

Is the optic nerve located in the temporal or nasal retina on fundoscopy?

Answer 2

It is loccated in the nasal retina on fundoscopy

Question 3

In the optic pathay, where does the optic nerve change to the optic tract?

Answer 3

the optic nerve changes to the optic tract at the optic chiasm

Question 4

Where does the optic tract change to the optic radiation?

Answer 4

Changes at the lateral geniculate nucleus located in the thalamus

Question 5

Where do the optic radiations synapse?

Answer 5

they synapse at the posterior occipital lobe in regins called calcarine sulci (fissure)

Question 6

The optic radiation spilts into a temporal and a parietal parts Does the temporal or parietal optic radiations supply superior quadrant vision?

Answer 6

The temporal parietal optic radiation (the outer radiation strand) carry information from the superior part of the visual field The parietal optic radiation (the inner one) carries information from the inferior part of the visual field

Question 7

State the defect each lesion would cause

Answer 7

• A - Right eye monocular blindness
• B - Bitemporal hemianopia
• C - Right eye nasal hemianopia
• D - Left sided homonymous hemianopia
• E - Left parietal lower quadrant hemianopia
• F - Left parietal upper quadrant hemianopia
• G - Left sided homonymous hemianopia with central (macular) sparing

Question 8

Where in the optic pathway are the lesions occuring?

Answer 8

• A - optic nerve - monocular blindness
• B - optic chiasm - bitemporal hemianopia
• C - right temporal retinal nerves - right nasal hemianopia
• D - right optic tract - left sided homonymous hemianopia
• E - right parietal optic radiation - left sided inferior quadrant hemianopia
• F - Right temporal optic radiation - left sided superior quadrant hemianopia
• G - defect in right visual cortex - causes left sided visual field homonymous hemianopia with macular sparing

Question 9

Up until the optic chiasm, lesions anterior are described as temporal or nasal side of the eye After the optic chiasm how are lesions described?

Answer 9

They are described as left or right

Question 10

Why is a visual field test carried out?

Answer 10

It is carried out to see if there is any defect in the optic pathway

Question 11

The visual field loss is seen on the same eye (ipsilateral) side as the lesion. Is this before or after the optic chiasm?

Answer 11

The visual loss is seen on the same side as the lesion before the optic chiasm

Question 12

What is the loop for the optic radiation that loops round the inferior horn of the lateral ventricle knwon as?

Answer 12

This is known as Meyer’sloop

Question 13

How does a lesion in the whole of the left optic tract present?

Answer 13

Would present with a right sided homonymous hemianopia

Question 14

what is number 1 and 2?

Answer 14

1 - optic chiasm 2 - optic tract

Question 15

If there is a visual defect in the inferior visual field eg a left sided homonymous inferior quadrantanopia, fibres from what region of the retina will be affect?

Answer 15

The superior retina Most likely a lesion in the right parietal optic radiation

Question 16

Where is the lesion causing a right sided homonymous superior quadrantanopia?

Answer 16

The lesion would be on the left temporal optic radiation This has the fibres from the inferior retina so supplies superior quadrant with vision

Question 17

When examining a patients visual field, should sit with a space between your knees Imagine a glass pane with four quadrants for examination What are the five stages of the visual field examination?

Answer 17

1. Ensure both yourself and patient are positioned correctly 2. Identify gross defects 3. Check quadrants by presenting fingers 4. Fine tuning findings using a white cotton wool bud (can use finger) 5. Examine blind spot of patient (using orange target)

Question 18

Ensure postioning correctly means to make sure both yourself and the patient are at eye level and you are an arms length away How do you identify any gross defects in the patients visual field?

Answer 18

Ask patient if they are able to see your whole face Then ask patient if they can see both your hands held up and ask if they can see two fingers

Question 19

How is the third step of the visual field examination carried out? Step 3. Check quadrants by using fingers

Answer 19

Either hold up one or two fingers Tell patient to cover one eye and hold finger(s) in each of the 4 quadrants (superior or inferior nasal/temporal) and cover one eye yourself Maintain eye contact with patient whilst they saw how many fingers they can see Once completed one eye do the same with the opposite eye

Question 20

If patient cant see fingers in either of the left inferior homonymous quadrants, what do you suspect?

Answer 20

Lesion in the right parietal optic radiation

Question 21

Step 4. Fine tuning findings using white cotton wool head This step assesses just how much of the visual defect the patient cant see (ie is it the whole temporal or whole quadrant) How is it carried out?

Answer 21

Paitent covers on eye Bring a white cotton wool tip in diagonally from superior or inferior (do each quadrant) and tell the patient to say now when they can see the cotton bud Do the same with the opposite eye

Question 22

Step 5 requires the examination of the blind spot How is this carried out?

Answer 22

This is carried out by telling the patient to cover one eye The orange cotton bud is then moved slowly temporally until the patient cannot visualise it also examine to see if the blind spot extends superiorly or inferiorly Repeat with the other eye

Question 23

Where is the blind spot located? What causes the blind spot?

Answer 23

The blind spot is located 15 degress temporal to central vision The blind spot is where the optic nerve is located (since the ganglion cells are located on the retina, can see before and after the blind spot)

Question 24

Blind spot

Answer 24

The point at which the optic nerve leave the eye, creating a “blind” spot because no receptor cells are located there

Question 25

What two diseases can cause an increased blind spot?

Answer 25

Both optic neuritis and papilloedema can cause increased blind spot

Question 26

If the defect in the eye affects the whole inferior visual field (known as inferior hemianopia), is the lesion located in the brain (after the optic chiasm) or the eye?

Answer 26

Must be a lesion in the eye - eg due to glaucoma affecting the superior part of the optic nerve

Question 27

What type of vision does age related macular degneration result in?

Answer 27

This results in a scotoma - so there is no vision in the central visual field

Question 28

What can macular degeneration cause in the visual field?

Answer 28

Macular degneration will cause a central visual field loss

Question 29

a lesion between the optic nerve head and the chiasm causing loss of vision in the central visual field

Usually unilateral, what is this?

Answer 29

This is known as a central scotoma

Question 30

What is a complication of age related macular degneration?

Answer 30

Central scotoma - complete loss of the cones causing no central vision