7.2 The following assessment was made on the visual field testing of a patient who presented with impaired vision.
(The darkened halves of the fields indicate the area of impaired vision).
a) What does the visual field testing indicate?
b) List 3 likely anatomical sites of lesion which may result in this visual defect.
a) What does the visual field testing indicate?
Rt. homonymous hemianopia
b) List 3 likely anatomical sites of lesion which may result in this visual defect.
Left optic tract
Left optic radiation
Left occipital lobe
The localisation of visual field defects lends itself especially well to a massive insane-looking eyeball diagram, which I have put together many years ago in med school.
For detailed references, one can be directed to Chapter 116 by R.H Spector from Clinical Methods(1990), or "Topical diagnosis of chiasmal and retrochiasmal disorders" by Levin, from Walsh and Hoyt clinical neuro-ophthalmology, 6th ed.
Alternatively, one can explore this table cut-and-pasted from the Required Reading section (Visual fields and lesions of the visual pathways). As you can plainly see, one can put "tumour" down as a cause for pretty much any of these
Lesion |
Localisation |
Causes |
Big blind spot |
|
|
Tunnel vision |
|
|
Central scotoma |
|
|
Unilateral blindness |
|
|
Bitemporal hemianopia |
|
|
Homonymous hemianopia |
|
|
|
Richly vascularised; difficult to take out with one ischaemic stroke: anterior choroidal artery and lateral geniculate artery are both involved in blood supply.
|
|
|
|
|
|
|
|
Homonymous hemianopia with macular sparing |
|
|
Superior quadrantinopia |
|
|
Inferior quadrantinopia |
|
|
Levin, Leonard A. "Topical diagnosis of chiasmal and retrochiasmal disorders."Walsh and Hoyt clinical neuro-ophthalmology, 6th ed. Baltimore: Williams & Wilkins (2005): 503-573.
Robert H. Spector. "Visual Fields." (1990). Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.