Vision Flashcards
Visual acuity
The ability of the visual system to clearly discriminate shapes and details in the environment
Strabismus
A condition in which the eyes do not align when looking at an object
May impact accurately reaching for objects and reading.
Saccades
Rapid, precise movements of the eyes between targets that functionally allows visual searching to occur.
An impairment is indicated by nystagmus or difficulty with isolating eye and head movements
Symptoms of convergence impairment
Blurred vision
Diplopia
Tired eyes when doing near-work activities
Visual accommodation
A mechanism of the eye that allows clarity of vision when a visual stimulus moves close to or away from the eyes.
Diplopia
Visual impairment secondary to a neurological event and may cause loss of depth perception and increase risk of falls
Examples of visual field deficits
Central scotoma
Homonymous hemianopsia
Quadrantanopia
How is visual acuity measured?
Measured by determining the refractive index of the eye, typically using the Snellen Chart
Field cuts
Age related macular degeneration
Primarily affects the central vision with the peripheral vision being preserved
Glaucoma
Glaucoma is a group of eye diseases caused by increased intraocular pressure that damages the optic nerve.
The effect on vision of glaucoma is loss of the peripheral visual field.
In early stages there are treatments that can prevent further vision loss.
Diabetic retinopathy
It is caused by changes in the blood vessels of the eye that affect the blood supply to the retina.
The result is loss of parts of the visual field seen as black areas at random points.
Cataracts
A clouding of the lens of the eye that results in blurred vision
Trochlear nerve palsy
Superomedial deviation
Abducens nerve palsy
Medial deviation
Oculomotor nerve palsy
Ptosis and deviation
List nerves of the lumbar plexus
Iliohypogastric (T12-L1)
Ilioinguinal (L1)
Genitofemoral (L1, L2)
Lateral femoral cutaneous (L2, L3)
Femoral (L2-L4)
Obturator (L2-L4)
Lumbosacral trunk (L4,L5)
Nerves of the sacral plexus
Superior gluteal n.
Inferior gluteal n.
Posterior femoral cutaneous n.
Pundendal n.
Sciatic n.
Varus and valgus stress
Lisfranc injury
Fracture of dislocation of midfoot
Most common dislocation
Hyperopia
Far sighted
Presbyopia
Far sighted due to age
Myopia
Near sighted
Astigmatism
Problem with a curvature of the lens, several problems
Retinal detachment
Separation of the retina from the choroid layer
Cobwebs, floating spots, flashes of light, shading
Medical emergency
Strabismus
“Lazy eye” (ambloypia)
Conjunctivitis
“Pinkeye”, irritants, colds, allergy
Modified methods for peripheral field loss
Teach scanning techniques
Increased lighting
Increased contrast
Modified methods for central field loss
Increased lighting
Eccentric viewing skills
Increased contrast
Magnifiers
Modified methods for decreased acuity
Increased lighting
Increased contrast
Magnification
Retinopathy of prematurity
Occurs with premature babies that were on high levels of oxygen
Nystagmus
Abnormal response and can interfere with reception
Lack of nystagmus is abnormal
Cortical blindness
Blindness that occurs in the brain
Ptosis
Droopy eye
OD
Right eye
OS
Left eye
OU
Both eyes
Hemianopsia
If on the same side as the dominate hand, they may not be able to track or use adaption of the UE
Miss parts of reading or omitting letters or small words
Visual perception
The total process of receiving and understanding visual stimuli
2 main components of visual perception
Visual reception
- Extracting and organizing information from the environment
- For example, straight vision says: blue shirt, man, brown hair
> Visual reception tells you that he is a man (organizing), he is out of the ordinary
Visual cognition
- The ability to organize, structure and interpret visual stimuli
- The ability to understand what is seen
Visual reception
Memories, knowledge, experience - give meaning to what you saw
Visual cognition
Take what you saw and use it physically, socially, cognitively, emotionally
Visual attention
Alertness
Selective attention
Shared attention
Visual vigilance
Visual memory
Recognition
Retrieval
Visual sequential memory
Can’t remember things in order
Visual spatial memory
The location of things in space
Visual discrimination
Ability to recognize, match, and categorize
Development of visual perceptual skills
Birth
- Reflexive fixation and tracking
- Nystagmus
8 Weeks - occulomotor control begins
- Tracking develops- complete by age 5yrs
* Cardinal planes of movement
* Head movement indicates a lack or incomplete development
Peak of occulomotor control is 18 yrs
Vision is the primary way an infant collects information
- Long before they can manipulate an object they can perceive it, recognize a pattern, have form constancy, and depth perception.
To start, they learn to identify objects based on general appearance and later learn to see specific details
- 18 month old: dog
- 4 year old: granny’s dog,
- 7 year old: that’s a poodle
Visual cognitive skills are vital for developing print awareness
- knowledge of letters and words and that they have meaning
Developmental ages to remember for vision
Visual Perception develops differently in different children: environment, opportunity, natural ability, and cognition
Typically developed by 9-10 years
- Figure ground-and form constancy: 6-7 yr
- Spatial relationships:10yrs
What can they draw?
- Verticals: 2
- Horizontals: 3-4 (people get arms)
- Laterality: 6-7 yrs
* Understand or recognize reversals- should stop mixing up b and d
* circles, the letter C
- Directionality: 8-9 yrs
How do visual perceptual skills develop?
General to specific
- Dog
- Brown dog
- Big brown dog
- Big brown short haired dog, lab
Whole to part
- Doll
- Doll’s dress
Concrete to abstract
- “There is a crack in everything, that is how the light gets in”
Familiar to novel
Agnosis
The inability to name an object known to the individual through visual means but able to by feel
- Right occipital lobe damage
Color agnosia
Inability to remember what color things should be (grass)
Color anomia
Inability to name a color
Metamorphopsia
Inability to distinguish the size or weight of an object, often distorting the size
Prosopagnosia
Inability to ID familiar faces
- lesion to R posterior hemisphere
Astigmatism
Problem with a curvature of the lens, several problems
Light rays focus on more than one point (unequal refraction of light in different meridians)
Nystagmus
Horizontal or vertical
Congenital or acquired
Meniere’s Disease, Head Injury, Tumor,
Idiopathic, drugs
- Post-rotary is normal
May or may not blur vision
Also the result of the Caloric Test
Impact to OT
- Medication review
- Impact to balance or gait
Warren’s hierarchal model of visual processing
Registration of visual input –> pattern recognition –> visual memory –> visual cognition
2 main components of visual perception
Visual reception
- Extracting and organizing information from the environment
Visual cognition
- The ability to organize, structure and interpret visual stimuli
