Visual Fields Intro

Question 1

What is hemianopia?

Answer 1

Loss in half of the VF

Question 2

What is quadrantanopia?

Answer 2

Loss of a quarter of the VF

Question 3

What does homonymous mean?

Answer 3

VF loss is on the same side in each eye

Question 4

What does heteronymous mean?

Answer 4

VF loss is on different sides in each eye

Question 5

If there is visual field loss in only one eye, where is the damage?

Answer 5

Before the optic chiasm

Question 6

If the VF loss is in both eyes, where is the damage?

Answer 6

At or after the chiasm

Question 7

If VF damage is heteronymous, where is the damage?

Answer 7

At the optic chiasm

Question 8

If VF loss is homonymous, where is the damage?

Answer 8

After the optic chiasm

Question 9

What is generalised VF loss? What might be a cause?

Answer 9

Diffuse, equal loss across the VF
Likely caused by a cataract, small pupil or poorly/uncorrected refractive error

Question 10

What is localised VF loss? AKA?

Answer 10

VF damage at a spot location
AKA focal or scotoma

Question 11

What is constriction VF loss?

Answer 11

Loss at the edges of the VF, causing ‘tunnel vision’ effect

Question 12

If a defect crosses the midline (H or V), what is the cause?

Answer 12

Photoreceptor damage

Question 13

If the defect respects the horizontal midline, what is the cause?

Answer 13

Defective RNFL cells

Question 14

What is included in a central scotoma?

Answer 14

Fovea

Question 15

What is included in a centrocecal scotoma?

Answer 15

Fovea and blind spot

Question 16

Where is a paracentral defect located?

Answer 16

Central vision, not including the fovea

Question 17

Where is an arcuate defect located?

Answer 17

Forms an arc shape from the blind spot, across either superior or inferior retina, doesn’t cross the horizontal midline

Question 18

What is the max extent of the visual field?

Answer 18

Temporal: 100 degrees
Nasal: 60 degrees
Superior: 60 degrees
Inferior: 75 degrees

Question 19

What is the purpose of VF testing?

Answer 19

Early detection of defects, assessment of baseline VF, and follow up of concerns

Question 20

What is the detection threshold?

Answer 20

Minimum brightness seen (first time px detects a light)

Question 21

What is static perimetry and what are the types?

Answer 21

Targets (lights) are shown to the px in a sequence
Types: Threshold and Suprathreshold

Question 22

How does threshold static perimetry work?

Answer 22

It either increases the brightness of the stimulus until it is just seen, or decreases until it’s not seen, or a combination of the two.

Question 23

How does suprathreshold static perimetry work?

Answer 23

Shows a stimulus at a known amount brighter than the threshold

Question 24

State an advantage and a disadvantage of threshold static perimetry.

Answer 24

Adv: accurate mapping of the whole VF
Disadv: time consuming, px may tire and get bored leading to inaccurate results

Question 25

State an advantage and disadvantage of suprathreshold static perimetry.

Answer 25

Adv: much quicker test than threshold
Disadv: less accurate mapping, may miss small focal defects or early VF loss due to estimated threshold

Question 26

What is kinetic perimetry?

Answer 26

Moving a spot of light, px reports when just seen or not seen

Question 27

When interpreting static threshold results, what distance is between each spot?

Answer 27

6 degrees between each spot
3 degrees between centre line and first spot

Question 28

On a deviation map, what is it grading against and what do + and - mean?

Answer 28

Grades against the normal for that age range.
+ = better than normal
- = worse than normal