Visual Acuity

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Visual acuity refers to how well one sees and to a measurement of the ability to clearly discriminate symbols at a given distance (Buktenica, 1958, and Barage, 1970). Most visual acuity tests require the child to distinguish and identify stimuli at 20 feet by 5 years. If he is able to accomplish the task, the child has perfect (20/20) vision. Legal blindness is 20/200 vision or worse in the better eye with the best refracted correction. That is, the legally blind child may see at 20 feet what the normally sighted sees at 200 feet. Partially sighted children have a visual acuity no better than 20/70. Vaughan and Asbury (1974) present the following progressing of visual acuity in children.

Age Visual Acuity
2 months 20/400
6 months 20/200
1 year 20/100
2 years 20/60
3 years 20/30
4-5 years 20/20

 

Near Vision

Reaches and grasps: observe accuracy of child’s reach and grasp. Use seven lotto cards: car, plane, doll, chair, shoe, ice cream cone, spoon. Ask the child to name each card at a near distance. If the child calls the pictures something other than what it is, accept the label, if she uses it consistently, you may tell the child the label if the is unfamiliar with it.

Shifts gaze: Hold two objects 6" apart. Attract her attention to one and then the other. Observe the speed and response behavior.

Distance Vision: use a tape measure to find 15 feet. At the 15’ distance again show the pictures to the child. She needs /50 vision to pass at this distance. Test both eyes simultaneously. Observe whether the child squints or attempts to move forward to backwards.

If he is able to name the cards at a close distance but not at the mark, move slowly toward the child in 5 foot intervals until he can see the picture and record the sources.

Visual Perception and Color Perception

Use color cubes – 7 colors; two of each color; ask child to match seven sets of two (all colors). Use beads of several sizes and string. Ask child to string them. Use pencil and paper and nine capital block letters: L, H, T, R O, U, A, V. Ask child to trace the letters with pencil. Watch for postural changes and wandering eye-hand movements. Use lock and key and ask child to insert key. Use shape sorter to ask child to insert three shapes.

  Yes No
Color cubes    
String beads    
Capital letters    
Lock and key    
Shape sorter or form board    
TOTAL    

 

 

  Yes No
Scoring    
Mobility and reflexive reactions    
Observable signs    
Visual behavior    
Near vision    
Distant vision    

(visual acuity)

   
Visual field    
Visual perception    
TOTAL    

 

 

 

 

 

How to use the score: more than two numbers in more than two categories should signal the caring parent or professional to seek further evaluation. Observable antidotal information should be recorded and used in supplementing categorical yeses and nos.

Fixates on 4” object-record no. of seconds (use red ball) At 12-18 inches; at 10 feet

Focuses with two eyes (binocularly) (use closed book)

Blinks at shadow of hand over eyes

Pupils constrict and dilate (use flashlight)

Tracks horizontally (use flashlight)

Tracks vertically (use flashlight)

Tracks circularly (figure-eight)

Light reflects on pupil at 12” (muscle balance –use flashlight)

 

Names (pins)(pellets)

  1. 3 objects very small (1”) at 5 ft.

 

  1. 3 objects kitchen utensil size at 5’ and 10’

 

  1. 3 objects clothing size 20-30’

 

TOTAL

The teacher should prepare the testing situation so that is is in a familiar setting—one with which the child has had experience and can feel comfortable and relaxed. As the teacher displays the materials on a low table or desk, questioning of the child can begin. ASK QUESTIONS which establish interest in the child and his vision:

Do you wear glasses?
Does anyone in your family?
What kind of lights do you like?
Very bright or do they hurt your eyes?
Can you see the animals across the room?
What’s blue and round sitting over there?

IF A CHILD WEARS GLASSES. TEST HIM/HER WITH GLASSES ON

Supplies

Lotto cards of objects
Miniatures set of objects: car, plane, doll, chair, knife, fork, spoon
Miniature set of animals and/or people
3 balls of graduated sizes: tennis ball and smaller
Pie tin
doll 5" high
Flashlight(s)
Slinky toy
Flint sparkler
Wind-up toys
Color cubes
Closed book
Pellets or sugar pills
Finger puppets
Color beads and string
White paper
Black marking pencil
Lock and key
Shape sorter or form board

Mobility and Reflexive Reactions Yes No
Runs backwards, forwards, to each side    
Moves legs and arms in alternation pattern (reciprocal)    
Orients peripherally by turning head left and right    
Climbs over obstacles; kicks, jumps, without falling    

 

Check off what child can do

 

X   X   X   X
Walks backwards   Uses tools, screws, unscrews   Tolerance for separation   Sense of time  
Circles Directed aggression   Sex modeling   Three words phrases  
Holds hands   Curious   Control of sphincters   Demands – short “I” – you code  
Pedals   Creative   Determination   Temporal awareness  
    Makes crisscrosses   Classification/property   Adds parts  
            Recall – memory improves  

 

Visual Assessment for Parents and Teachers of Young Children

Why Screen 2-5 Year Olds

Functional screening for potential visual problems is an integral part of educating young children. From birth, a child’s vision needs to be carefully observed by caring teachers and parents. The structural elements of vision need to be evaluated. They are

a) reflexive reactions;
b) mobility;
c) muscle balance and eye movements;
d)visual acuity: near and distance vision, and
e) visual perception (Langley and Dubose, 1978)

Some forms of ocular impairment occur in young children in the absence of other handicapping condition. Nystagmus (jerking of the eyes), strabismus (muscle imbalance), amblyopia (lazy eye), and estropia (crossed eyes) are among common dysfunctions occurring in the normal population that are amenable to correction.

Conditions such as optic atrophy, cortical blindness, or rentrolentalfibroplasia are most often identified at birth or in early infancy, and require specific early sensory – stimulation training in order to optimize existing vision.

The purpose of vision screening is to:
a) identify levels of functional vision,
b) refer any observed problem for further professional evaluation, and
c) enhance the child’s ability to use existing levels of vision.

Observe the Child at Play

Gearhart and Weishahn (1976) provide a list of characteristics and behaviors that may signal the presence of a visual problem in a preschool-age child:

 

Visual Behavior

Observable Signs Yes No
Red eyelids    
Crusts on lids among lashes    
Recurring sties or swollen lids    
Watery eyes or discharge    
Reddened or water eyes    
Crossed eyes or eyes that do not appear to be straight    

Pupils of uneven size

 
   
Eyes that move excessively    
Drooping Eyelids    
TOTAL    

 

 

  Yes No
Pushes, pokes eyes    
Shakes head from side to side    

Rocks repeated back and forth

   

Holds objects near eyes and spins

   
Holds objects and flicks or twirls    
Waves hands in front of eyes    
TOTAL    

 

 

 

 

Set-up for screening – Antidotal information

In 1989, Dr. Turben received funding that enabled the Cleveland Sight Center to initiate the first large-scale, family-centered Children's Services Program in Cleveland, Ohio. Dr. Turben worked for Lake County Early Intervention Collaborative Group in 1988-89 as the consultant who prepared the County Needs Assessment and assisted the collaborative in the preparation of the 1988-89 Lake County Early Intervention Collaborative Plan, which launched family collaboratives as a network of families with children who had disabilities.
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