Vision Checkoff Flashcards
Vision
- Primary sensory system used to acquire information about the environment
- 80-90% of all learning occurs through visual channel
- 90% of all sensory info supplied to CNS is visual
Vision if the most far reaching sensory system because it…
- First to alert us to danger or pleasure
- Enables us to be anticipatory
- Helps plan for situations
Contributions of Vision
- Supplies info for congitive functions (problem solving, decsion making)
- Supplies info/clues needed to interpret social interactions
- Supplies input for motor and postural control
- Provides speed in info processing
Supplies input for motor and postural control (Contributions of Vision)
- Facilitates motor development
- Warning system for challenges to postural control (100ft)
Provides speed in info processing (Contributions of Vision)
- Speed is critical when it comes to adapting to dynamic environment
- Rapid processing of visual info for adaptive response
Visual Perception
-The ability to organize and interpret the info that is seen and give it meaning Includes: -Form constancy -Figure-Ground -Visual Closure -Visual Memory -Spacial Orientation -Visual Discrimination -Spacial Relationships
Normal Vision
20/20-20/30
Near Normal
20/30-20/60
Moderate Impairement
20/70-20/160
Severe Impairment
20/160-20/240
Profound Impairment
20/400-20/1000
Near Blindness
20/1000-20/2500
Total Blindness
No light perception
Legal Blindness
Term coined by the federal government to describe visual impairment criteria qualifying individuals for benefits and services
- Best corrected VA 20200 or less in better eye or
- VF of 20 degrees or less in better eye
Can occur at birth or from…
-Disease
-Trauma
-Aging
-or Combination
(Age-related Macular Degeration, Diabetic Retinopathy, Glaucoma, Enucleation)
Visual Impairments
- Alter the quality/quanity of visual input to CNS
- Alter the CNS ability to process visual input
- Result in decreased ability to use vision for occupational performance
- Alter cognitive performance
- Can contribite to anxiety, decrease confidence, social isolation, etc.
OT Role in Low Vision Rehab
- Focus should always be on occupational performance
- Purpose of eval is not to diagnose but to link presence of visual deficit or disorder to limitation in occupational performance
- Observation of patients funcitonal performance and environment are critical
Two Treatment Approaches (OT Role in Low Vision Rehab)
- Client Centered: Emphasis on changing the person, improving ability to take-in and process visual infor
- Environment-Centered: Emphasis on altering the environment to achieve better person environment fit, enables person to engage with remaining capabilities
Cataracts
- Lens becomes opaque or cloudy
- Cataracts prevent light from reaching retina, causing difficulty with night vision
- Cataract surgery is common, new lens is implanted
Macular Degeneration or Age-Related Macular Degeneration (ARMD)
- Loss of Central Vision
- Leading cause of vision loss in adults
- Responsible for fine-detail visions (reading, needlework, recognizing faces, writing)
- Dry degeneration is more common
- Wet degeneration can be treated with laser surgery
Glaucoma
- Loss of peripheral vision
- High pressure inside eyeballl results from buildup of excess fluid in the eye, Pressure eventually damages the optic nerve or the blood vessels that supply the optic nerve
- If left untreated, leads to total blindeness
- Treated easily with eye drops or surgery
- Two Types: Open Angle and Closed Angle
Open Angle Glaucoma
Progresses slowly with a gradual buildup
CLosed Angle Glaucoma
Progresses rapidly with symptoms
4 Stages of Diabetic Retinopathy
- Mild Nonproliferative Retinopathy
- Moderate Nonproliferative Retinopathy
- Severe Nonproliferative Retinopathy
- Proliferative Retinopathy
Functional Implications of Diabetic Retinopathy
Such as glaucoma, varies depending on early diagnosis and severity of the disease
Homonymous Hemianopia
Partial or complete loss of vision in one half of each eye
Vision and Functional Mobility
- Simultaneously process info from both central and peripheral VF
- Primarily used to gather info about obstacles, objects to be manipulated or acted upon
- Used to plan movement & postural adjustments (motor planning), movement is visually triggered
- Environmental qualities (static/dynamic, new/familiar, simple/complex)
- Must consider other environmental features (brighness, glare) contrastinh features (curb drop-offs, stairs)
- PVF loss (glaucoma, central retinal artery occlusion) result in collisions, balance disturbances, and disorientation)
Treatment of VFD
- Simple Scan Course
- Dynavision D2
Indoor Mobility
- Familiar environment (home, school)
- Trailing
- Alignement
- Squaring-Off
- Room Familiarization (landmar, boundary, grid)
Trailing (indoor mobility)
Continuous surface between destinations (ambulating down hallway)
-Extend shpuld 45° arm in from of body and use back of hand with fingers curled
Alignment (indoor mobility)
Use whern there are gaps in trailing surface (countertop, kitchen sink, crossing doorways)
-Client aligns self parallel with surface to establish line of travel, then continues across open area to resume trailing on other side
-
Squaring-Off
Use when changing directions or crosing a surface with gaps (countertop, kitchen table)
-Client places back against object to determine line of travel away from object
Sighted Guide
- Used to safely navigate unfamiliar or dynamic environments
- Client grips ‘guides’ arm just above elbow tieh fingers on inside of elbow and thumb on outside
- Guides arm relaxed at side and client with elbow bent at 90°
- Navigating Narrow Passages (doorways)
- Stairs/ Curb
- Guide provides VC as alert to changing environment
- Effective training will result in improved safety for client in dynamic novel environments
- Orientation in clinic and practice at home
- Other mobility options: Long cane training
Navigating Narrow Passages/Doorways (Sighted Guide)
-Guide moves arm back towards center of back and client responds by exending arm and flies in (moves into) single-file, arm held fully extended to prevent tripping
Stairs/ Curbs (Sighted Guide)
Guide alerts, square off with steps, cue for handrail, guide initiates step then client, guide cues client at/before landing
Oculomotor Review
- Fixation: Abilityy to focus/fixate on target
- Localization: Ability to spot different objects/items, move eyes from one place/point to another within VF
- Saccadic Movements: Shift and fixate from one target to another
- Smooth Pursuit (aka tracking): Following/ Tracking targets
Oculomotor Review Steps
Fixation (maintianing the picture) > Localization (looking for target anywhere in VF) > Saccades (looking btw 2 objects) > Smooth Pursuits (following objects/targets)
Visual Assessments
- Pupillary Contriction
- Saccadic Eye Movements
- Snellen Eye Chart (VA)
- Eye Dominace Testing
- Smooth Pursuit (visual tracking)
- Convergence/Divergence
- Visual Field Testing
- Central Cisial Fiels
- Confrontation Testing (Red dot & 2 Person Kinetic Tests)
Pupillary Contriction (Visual Assessments)
Pen light 3-4” from pupil
Saccadic Eye Movements (Visual Assessments)
(horizontal/vertical)
- Hold 2 targets (letters on tongue depressor, different color items), one in each hand 16” from client’s face. targets 8” apart
- Client looks at one then rapid shift to fixate on other (observe eyes moving together, smoothly finds target; note over/undershooting) 5x. (don’t mention head movement)
Smooth Pursuit/Visual Tracking (Visual Assessments)
- Hold target ~16° from clients face, slowly move CWx2, then CCWx2
- Assess square and diagonal ‘X’ (observe keeping head still while moving eyes to follow target, eyes move together, smoothly follow object, under/overshooting, midline jerk: looks away when object crosses persons midline)
Convergence/Divergence (Visual Assessments)
- Hold object ~16” from client’s face, slowly move object towards bridge of nose, stop when client reports object is blurry ~2-4” from bridge of nose
- Move object back out few inches (re-focus), observe both eyes should be moving equally in, excessive blinking, turn in/out excessively, inability to move in/out, >3” convergence insufficiency)
Visual Field Testing (Visual Assessments)
All tests are monocular
- Central Visual Field (CVF)
- Confrontation Testing (red dot & two person kinetic testing)
Central Visual Field (Visual Assessments)
- Focus on center of clock (client identifying any missing #’s), Test fro scotomas in CSF
- Alternatively, can ask client if any part of examiners face is missing
Confrontation Testing: Red Dot & Two Person Kinetic Testing (Visual Assessments)
- These are gross assgessments and may not be sensitive enough to detect subtle changes
- Defiticits to peripheral VF usually dont interfere with reading/near vision tasks but can cause significant mobility issues
- Observe: Client remains fixated on target or examiners eys, does not break fixation during testing
Visual Perception Hierarchy
- Adaptation Through Vision
- Visual Cognition
- Visual Memory
- Pattern Recognition
- Scanning
- Attention (alert and attending)
- Oculomotor Control, Visual Fields, Visual Acuity
