Lecture 8: The Visual System Flashcards
What is Optometry?
A specialization in optimization of eyes optic
What is Ophthalmology?
Physicians who specialize in diagnosing and treating diseases of the eye
What is Neuro-Opthalmology?
Ophthalmologists who specialize in diseases affecting the neural aspects of the peripheral visual system
What are the 2 Cortical Visual “Streams” that protect from the Occipital Lobe?
Ventral Visual Stream and Dorsal Visual Stream
What is Ventral Visual Stream?
Associated with object perception and recognition disorders are referred to as Agnosias
What is Dorsal Visual Stream?
Associated with object manipulation and visually guided reaching
The disorders are referred to as Apraxias
What are the 3 Tests of Visual Function?
Test of Central Vision, Tests of Whole Field Sensitivity, and Higher Level Visual Perception
What is Test of Central Vision?
Vision nears the fixation point of centre of gaze (e.g visual acuity, colour vision)
What is Whole Field Sensitivity?
Perimetric field tests, dark adaptation tests, flicker sensitivity tests
What is Higher Level Visual Perception Test?
Attention, visual search, object/face recognition, wayfinding, etc…
What is Agnosia?
A failure of recognition that cannot be attributed to elementary sensory deficits, mental deterioration, attentional disturbances, aphasic misnaming,etc..
What is Visual Agnosia?
Due to damage in the ventral visual stream (terminating in the inferotemporal cortex)
What is Apperceptive Agnosia?
Deficit in the ability to develop a complete percept of an objects
This an object agnosia
What is Simultagnosia?
Unable to perceive more than one object at a time
This an object agnosia
What is Associative Agnosia?
Failure to connect the output of perceptual analysis to patients knowledge
This an object agnosia
What is Prosopagnosia?
Ability to identify features not the inability to recognize familiar faces (e.g famous people, friends, relatives)
What is Landmark Agnosia?
Inability to utilize features of the environment in wayfinding
What is Visuo-Spatial Neglect?
A failure to report, respond, or attend to stimuli or events in the hemifield contralateral to a brain injury
What are 4 Standard Tests of Spatial Neglect?
- Line Bisection
- Cancellation
- Spontaneous drawing or copying clock face drawing
- Metal Imagery memory colour neglect
What is Colour Agnosia?
Inability to name colours or to sort different coloured patches into groups of the same colour
What is Central Achromatopsia?
Complete loss of colour perception due to damage to V4
What is Colour Anomia?
Inability to name colours
What is Specific-Colour Aphasia?
Verbal questions of colour cannot be answered
Symptoms of Dorsal Stream of Vision?
Getting lost in crowded places, finding someone in a group, seeing a distant object in a large scene, difficulty waking over uneven ground and steps, bumping into things when talking and walking, difficulty switching between 2 visual tasks
