Visual Systems Flashcards
Visual Motor vs. Visual Perceptual Systems
MOTOR: eyes and body; hand/eye coordination.
PERCEPTUAL: how eyes see things; interpretation
Visual Perception
Total process responsible for the reception and cognition of visual stimuli. Includes:
• Visual-Receptive (receiving stimuli)
• Visual-Cognitive (understanding/using stimuli)
• Visual Information Analysis (integration with other systems)
Anatomy of Eye
Part of Visual-Receptive Components of visual performance.
• Cones (color)
• Rods (night/peripheral)
• Pupillary cells (dilation/constriction)
• Fovea Centralis (point of clearest vision)
• Optic Nerve (transmit to brain)
Ocular Motor System
Part of Visual-Receptive Components of visual performance. • Fixation • Pursuit/Tracking • Saccadic Movement • Acuity • Accommodation • Binocular Vision • Stereopsis • Convergence/Divergence
Fixation
Ability to hold focus on something.
Pursuit/Tracking
Ability to follow an object with eyes.
Saccadic Movements
Eyes jump between two points (need this to read).
Acuity
How well you see.
Accommodation
How eyes work to focus on something (changing optical power based on distance).
Binocular Vision
Ability to maintain focus with both eyes, creating a single image.
Stereopsis
Ability to see depth by info from both eyes.
Convergence/Divergence
Ability of eyes to move to focus on something moving closer/farther from face (cross eyes, etc.). Causes double-vision or loss of depth perception if not functioning.
Visual-Cognitive Components of Visual Performance
- Visual Attention
- Visual Memory
- Visual Discrimination
- Object Perception
- Spatial Perception
- Visual Imagery
Visual Attention
“Focus” on an activity, visually. • Alertness • Selective attention • Visual vigilance (keeping eyes on something, not darting around) • Divided or shared attention
Visual Memory
Ability to look at something and recall it (ie: a sentence to copy); or, to recall the shape of something (ie: a letter)
Visual Discrimination
- Recognition of things
- Matching of things
- Categorization of things
Object Perception
- Form Constancy
- Visual Closure
- Figure-Ground
Spatial Perception
- Position in space
- Depth perception
- Topographic orientation
Visual Imagery
Having “pictures” in the mind. Visualization.
Visual Perception Difficulties Affect Performance Areas:
- Problems in ADLs
- Reading
- Spelling
- Handwriting
- Visual-motor integration (convergence to catch a ball, bilateral coordination, etc.)
- Mathematics
Signs of Visual Problems
- Eyes shake and randomly wander
- Child appears clumsy
- Child frequently rubs eyes
- Large, small, or irregular pupils
- Child covers/closes one eye
- Child responds better to objects on one side of body
- Child sits excessively close to tv
- Child complains of tired eyes
- Child avoids/becomes tired from close work
Intervention Ideas for Visual Perception
- Address areas similar to children without difficulties
- Grade activities to address performance with low/no vision
- Address visual perceptual/visual motor
- Develop tactile-proprioceptive perceptual abilities
- Improve fine motor skills
- Enhance postural control and movement in space (body awareness, spatial orientation)
- Address sensory defensiveness (grade tactile activities to integrate input; calming before activities)
Intervention Types for Visual Perception Difficulties
- Developmental/Neurophysiologic
- Compensatory (audio books; google read)
- Developmental optometry
- Vision therapy (experts in vision issues; better than OT)
** After 3rd grade, consider compensatory methods BEFORE remediation for reading deficits.
