Quiz 2 Flashcards
3 Component Model of Vision
Considers:
Visual Integrity
Visual Efficiency
Visual Information Processing
1 Component Model of Vision
Only evaluates visual integrity (acuity, refraction, & eye-health)
Not sufficient to detect vision problems that are prevalent in peds population
Visual Integrity
- Visual Acuity: The ability to see fine detail
- Refractive Error: The optical characteristics of the eye (myopia, hyperopia, astigmatism)
- Eye Health: health of all components of the visual system from the eye to the brain
Visual Efficiency
Accommodation: the ability to change focus from near to far objects
Binocular Vision: the ability to use both eyes in a coordinated manner
Eye Movements: the ability to maintain steady fixation on an object, look from object to object, and follow moving objects
Visual Information Processing
Visual Spatial: ability to understand right and left on one’s own body
Visual Analysis: ability to analyze and interpret visual stimuli
Visual Motor Integration: ability to accurately reproduce a visual stimulus
Eye Care Professionals
Opitcian: helps select appropriate eyeglasses frame ( no training to perform clinical testing)
Ophthalmologists: diagnose and treat using meds and surgery
Optometrists: MD, use 3 component model
Down Syndrome & ASD vision problems
commonly have refractive error, accommodative problems, and strabismus
Convergence Insufficiency Survey Vision Screening
CISS score of > 16 suggests visual inefficiency, vision screening should be considered
CISS score by itself should not be the basis for concluding that a vision problem is present
Visual Acuity Problems
Myopia: nearsightedness (far away objects are blurred but near objects are clear)
Hyperopia: farsightedness (nearby objects are blurry) most common refractive error in childhood
Astigmatism: vision is blurred at both distance and near
Amblyopia: lazy eye
Ocular Development
-structures that will be eyes appear at 4 weeks gestation
-by 7 weeks gestation they form into eyes
Coloboma: pupils look like keyholes; cleft like defect in eyes (have CHARGE syndrome) -bludging small eyes
Hypertelorism: abnormally wide spaced eyes
Intrauterine infections can cause cataracts,
glaucoma or inflammation of the retina
Development of Visual
Skills
At 3 months:
-infant can fix a steady gaze and track a small target at near range and eyes become straight at this age
-Visual acuity improves fivefold in the first 6 months
By 3-4 years
-vision can be objectively measured by
identifying a series of pictures at a distance for
20/40 vision or better
By 6 years old
-visual acuity should be 20/30 or better and if
possible should be measured with letters
Binocularity
Determine eye alignment and how well eyes work together as a team: skill and endurance
Signs of dysfunction:
-Struggle with visual tasks
-Take long time to complete a task
-Normal amount of time but with discomfort
-Avoid tasks
Accommodation
ability to change the focus of eyes so that objects at different distances can be seen clearly
Accommodative disorders can interfere with any activity that requires visual concentration on small objects or print at a close distance
Ocular Motility
Determine the range that the eyes can move
-Test R and L eyes separately
-Should be able to go full range when follow target (held 16 inches from face) in circle
Saccades
- Ability to move eyes to scan environment and track while reading
- Rapid changes in fixation in the visual field from one point to another
- Tested by direct observation for overshooting or undershooting
- child is asked to look back and forth repeatedly between two targets (8-10
inches apart) - Targets should be approximately 12 inches in front of the child’s face
- Assess in horizontal, vertical and diagonal planes
Pursuits
Pursuits: is slow, coordinated movement of both eyes following a moving target
* Child is asked to follow a moving target that is 12-16 inches from the child’s face
* Assess in horizontal, vertical, and diagonal planes
* Eyes should be tested separately then together
* Test: direct observation for tracking of object
* 4 y/o will probably move head, but if asked, should be able to follow target with
eyes
Abnormal Ocular Motility
- Head movement
- Jump of lines during reading
- Automatic use of head
(unacceptable after age 6) - Undershoots (does not go far enough)
- overshoots (too far and come back (unacceptable after age 7)
Visual-Motor Skills
ability to
integrate visual information
processing skills with fine motor skills. Eye-hand coordination
Visual analysis skills
ability to analyze and discriminate visually presented information,
determine whole without
seeing parts.
2 skills of visual spatial abilities
Visual Spatial analysis:
-spatial properties of objects are analyzed (eg. Chess game)
Visual Construction:
-A perceptual activity with a motor response that includes drawing and
assembling
-replication of spatial aspects of objects
-Copying drawings/models
Vestibular Ocular Reflex (VOR)
-Responsive at birth
-Maintains stable vision on retina during head movements
-Eye movements are fastest and most frequent
movements made by body
-Provides eye-hand coordination
Nystagmus
rhythmic oscillation of eyes that occurs during or after head movement (Rapid jiggling back and forth (mainly horizontal) of the eyes)
-Decreased eye head control
-Poor tolerance of visual motion
-Dysfunction can have direct effect on efficiency of reading and school performance
-Causes: small optic nerve, underdeveloped fovea, variety of rods and cones abnormalities
-Can be latent (only present with occlusion of one eye)or manifest (constant
at all times)
Oscillopsia
perception that objects are bouncing during
head movements (bilateral vestibular dysfunction)
Post rotary nystagmus testing
-Position child with head tucked and eyes closed
-Spin for 8-10 repetitions
-Observe for nystagmus immediately after
-Abnormal-
no response,
hypo- response, asymmetry
hyper-response ( greater than 18 seconds)
Amblyopia
unilateral in which a “healthy” eye is turned off or ignored by the brain
-Treated with glasses, patching, or eye drops to blur the vision of the better seeing eye encouraging the
brain to use and develop vision in the amblyopic
eye
Strabismus
-Esotropia: cross- eyed, eyes turn in
-Exotropia: cross -eyed , eyes turn out
Hyper-deviation: vertical misalignment of eyes
common with CP
surgery can be done to adjust
Eye patching before age 6: 2hrs a day for 3-6 months
Cataract
first appears as a white spot in the pupils or both eyes. If untreated, it will cause
amblyopia
If cataract is larger than 3mm then surgery is
required
Better outcomes in infants if surgery is done
before 6 weeks of age
Optic nerve hypoplasia
small thin optic nerve transmits impaired
information to the brain resulting in decreased vision
-uncorrectable with glasses. Often associated with other developmental disabilities