Visual Field

Question 1

what is a scotoma

Answer 1

A circumscribed area of loss of vision in the visual field e.g. the normal blind spot

Question 2

what is a heminaopia

Answer 2

Hemianopia
Loss of half of the field of vision with a vertical border

Question 3

what is a qudrantopia

Answer 3

Quadrantinopia
Loss of quarter of the field of vision with a vertical border

Question 4

what is an altiduinal defect

Answer 4

Altitudinal defect
Loss of half of the field of vision with a horizontal border

Question 5

what is arcurate

Answer 5

A scotoma that is shaped like an arc of a circle

Question 6

what is sectoral vision loss

Answer 6

A field defect that is ‘pie-shaped’ and extends from the blind spot

Question 7

what is hmonymous visual field loss

Answer 7

Affecting the same side of the visual field for both eyes

Question 8

what is bitemporal vision loss

Answer 8

Affecting the temporal field of both eyes

Question 9

what is confrontational visual field testing helpful for

Answer 9

This is only helpful for detecting:
Hemianopias
Altitudinal defects
Large central scotomas

Question 10

what is automated field testing used for

Answer 10

For detailed analysis of the visual fields, automated techniques for measuring and recording visual fields are essential
Goldman fields are useful in neurological disease
Humphrey fields are essential for the management of glaucoma

Question 11

how are visual field defects recorded

Answer 11

Each method of visual field testing has a different method of recording
Confrontation testing produces a description of a defect and a possible sketch in the notes
Goldman testing produces a series of ‘isopters’ rather like contour lines on a map
Humphrey testing produces a grey scale diagram of the defect showing pattern and intensity of defect

Question 12

how fields of confrontation recorded

Answer 12

By convention the fields are recorded as the patient sees them
To reduce confusion it is helpful to label each field
This is how a left homonymous hemianopia might be recorded

Question 13

what vf defects does the retina produce

Answer 13

retinal problems produce uniocular defects which mirror the location of the abnormality
This patient has a superior temporal retinal detachment in the left eye
This produces an inferonasal field defect in the left eye

Question 14

what visual field defect will a superior artery occlsuion
in the retina cause

Answer 14

A superior retinal artery occlusion will cause an inferior altitudinal defect
The blood supply to the retina has a border running horizontally through the macula with very little overlap

Question 15

what visual field loss will macular disease cause

Answer 15

The macular supports central vision
Macular disease causes a loss of visual acuity and a central scotoma
This patient with bilateral macular degeneration has bilateral central scotomas

Question 16

what will optic nerve visual field problems will be caused

Answer 16

Optic neuropathies produce a variety of field defects depending upon pathology
The commonest defect is a central scotoma
Optic disc infarction in anterior ischaemic optic neuropathy may produce a sectoral or altitudinal defect

Question 17

what is optic neuritis

Answer 17

This patient developed optic atrophy after an episode of optic neuritis caused by multiple sclerosis
She has reduced visual acuity, a relative afferent pupillary defect, loss of colour vision and a central scotoma

Question 18

what visual field does early glaucoma cause

Answer 18

Glaucoma produces a variety of field loss depending upon severity
Early glaucoma causes an arcuate scotoma

Differential loss between upper and lower fibres at the optic disc leads to a step in the nasal part of the visual field

Question 19

what does more extensive cupping of the disc cause

Answer 19

More extensive cupping of the disc causes altitudinal defects

Question 20

what vf defects does advanced glacucoma cause

Answer 20

Finally advanced glaucoma causes tunnel vision as superior and inferior defects join up
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Question 21

importance of the optic chiasm

Answer 21

At the chiasm, fibres from the nasal retina (temporal field) cross to the opposite optic tract
the boundary runs through the centre of the visual field (through the macula) and not through the optic disc

Question 22

antomical relationships of the chiasm

Answer 22

The chiasm lies in the anterior part of the third ventricle
It is 1cm above the pituitary gland

Question 23

chiasmal compressions leads to what vf defect

Answer 23

The hallmark of chiasmal compression is a bitemporal hemianopia
The nasal crossing fibres in the chiasm are compressed first, which causes loss of temporal field in both eyes

Question 24

pituitary tumour causses what

Answer 24

A pituitary tumour will compress the chiasm from below
This will cause damage to inferior fibres first
This leads to a bitemporal defect affecting the superior field

Question 25

pituitary tumour causes

Answer 25

Pituitary tumours may compress the optic nerve and optic chiasm
This leads to a central scotoma in one eye and a superior temporal defect in the other
This is referred to as a junctional scotoma
Non-secreting tumours often present with visual loss in this way

Question 26

what does a craniphrarnygioma cause

Answer 26

Craniophryngiomas develop above the chiasm
Compression therefore affects the inferior field and progresses to a bitemporal hemianopia

Question 27

describe the visual pathways

Answer 27

From the chiasm, the visual pathway continues into the optic tracts
Fibres in the optic tracts synapse in the lateral geniculate nucleus below the thalamus
The pathway continues in the visual radiations to the occipital cortex
Visual defects from now on affect the same side of vision in both eyes and are therefore homonymous

Question 28

optic tract lesions cause what

Answer 28

These are usually vascular
Fibres from the retina which represent the same parts of the visual fields have not yet come together
This means that defects are not the same in each eye’s visual field
A lesion of the right optic tract will therefore produce a left sided incongruous homonymous hemianopia (as shown above)

Question 29

visual radiations

Answer 29

From the lateral geniculate nucleus, fibres spread into the parietal and temporal lobes
Temporal lobe lesions affect superior field
Parietal lobe lesions affect inferior field
Lesions are vascular or due to space occupying lesions and are accompanied by other neurological defects e.g. hemiplegia

Question 30

lesions affecting the visual field usually cause what

Answer 30

Lesions affecting the visual radiations are congruous i.e. the same size in the field from each eye
This is a highly congruous left homonymous hemianopia affecting the inferior field more than the superior field
Diagnosis?
Right parietal lobe lesion, probably after a stroke

Question 31

vf defects after lesion at occipital cortex

Answer 31

Lesions of the occipital cortex are usually vascular
The cortex is supplied by middle cerebral, posterior cerebral and anterior choroidal arteries
This means that a variety of homonymous hemianopias can be produced by lesions in this area

Question 32

occipital lobe infarct causes what

Answer 32

A right posterior cerebral artery occlusion will cause a left homonymous hemianopia
The macular area is supplied by the middle cerebral artery and is spared
The extreme left temporal field is preserved because of the anterior choroidal artery

Question 33

if an infarct occurs at the cortex below the clacrine sulcus what happens

Answer 33

If an infarct damages the cortex below the calacarine sulcus, only the superior field will be affected
This will produce a defect with vertical and horizontal borders

Question 34

retinal disease produces…

Answer 34

Retinal disease produces a defect in one eye

Question 35

optic nerve disease produces a

Answer 35

Optic nerve disease produces a central scotoma

Question 36

chiasmal compression causes

Answer 36

Chiasmal compression produces a bitemporal hemianopia or a junctional scotoma

Question 37

anything behind the chiasm produces a

Answer 37

Anything behind the chiasm produces a homonymous hemianopia on the opposite side

Question 38

tract defects are

Answer 38

Tract defects are incongruous

Question 39

radiation defects are

Answer 39

Radiation defects are congruous

Question 40

occiptial strokes cause

Answer 40

Occipital strokes cause macular sparing defects