Vision Flashcards
optic disc
Blind spot
Fovea
light sensitive inner lining of the eye (sends electrical signals to the brain to stimulate visual recognition. (greatest ability to process detail)
Macula
Inside the fovea- the spot where vision is the most highly developed
impaired by CVA
if one ocular muscle is unable to focus eye, it creates double image
Vision
Primary sensory system used to acquire information about the environment. the most complex system (furthest reaching sense). the fastest sensory system.
Optical system- ability to see objects
Cortical system- ability to interpret what is being seen
Visual processing
allows us to anticipate information necessary for successful adaptation to the environment
Focal- attentive vision (what you focus on)
Ambient- peripheral vision
information processing
Need a clear optical image- optical input
Integration- sensory information is blended and results in plan which guides response. information blended into thought, recognize objects
Output- Ocular-motor response (guides behavior, eye hand coordination and commuting mobility)
Visual perceptual hierarchy of skills
- Oculomotor control, visual fields, and visual acuity
- Attention (alert and attending)
- Scanning
- Pattern recognition
- Visual memory (try and make a picture out of object we just saw)
- Visuocognition
- adaptation through vision (what is our response)
Pattern recognition
The ability to identify the holistic aspects of an object: to see its general shape, contour, and features.
ability to identify features of an object and use features to distinguish the object from its surroundings.
Visual memory
the ability to create and maintain a picture of an object in the minds eye. Keeping and storing an image and calling it up at a later date.
Must be able to store and recall from ST and LT memory.
visuocognition
the ability to manipulate visual information mentally and integrate it with other sensory information to gain knowledge and to solve problems, formulate plans, and make decisions.
foundation for reading, writing, math, etc…
cannot occur without the presence of visual memory.
neurologic dysfunction
Focal system is compromised.
Integration is disrupted:
-between focal and ambient systems
-between visual system and other sensory inputs.
Can disrupt visual processing at any level in the hierarchy
Glaucoma
the mechanical compression and or decreased blood flow of the optic nerve and nerve damage and visual loss can occur.
Leading cause of blindness throughout the world.
Macular degeneration
Destroys the macula. Where vision is most highly developed. results in impairment in our central vision. Causes blindness and only focuses on central vision.
Retinopathy
blood vessels in retina, untreated can lead to blindness. Treatment is laser therapy or medication
Cataracts
small splotches, easy to take care of. (cloudiness of the lends and impairs vision)
readiness for evaluation
- time of day
- room illumination
- corrective lenses during testing
- positioning (sees better sitting or standing)
- ability to communicate
OT vision assessment
- Visual acuity
- Visual field loss
- Oculomotor impairment
- attention (visual attention)
Visual acuity
clarity of vision- prerequisite for rest of visual system.
- CNS processing records 4 primary spatial components:
- frequency (what are we looking at)
- Orientation (vertical, horizontal)
- Contrast (what separates it from the ground or background)
- Intensity (the deepness of color)
focusing problems are fairly common.
Deficits in acuity (myopia, presbyopia, hyperopia, astigmatism)
Controlled by CN III (oculomotor)
Myopia
Nearsightedness (located in front of retina instead of on it)
Presbyopia
Farsightedness (hardening of the lens)
Hyperopia
Farsightedness (eye is too short from front to back, image behind retina instead of on it
Astigmatism
Unequal curvature of one or more of the refractive surfaces of the eye (the cornea) blurry vision. prevents light rays from focusing clearly on one place.
Vergence system
aligns eyes to maintain binocular fixation and binocular vision.
