Vision is more than acuity
As you learned in the textbook, vision
is an important component for learning about the world and completing academic
tasks. However, vision is more than acuity, and the effects of inadequate
vision are found in students who have learning disabilities, mental
retardation, and traumatic brain injuries. In fact, research suggests that at
least 80 percent of the students with reading problems may have functional
vision problems (Li, 2004). If students are to be successfully and fully
included in classroom activities, teachers should recognize the possibility of
functional vision loss and refer children for assessment and treatment of this
loss. The table below lists vision problems commonly associated with loss of
functional vision and possible symptoms seen in children with such losses. As
you read this table, try to think of the school tasks that will be problematic
for students who lack these visual skills.
|
Visual skill
|
Symptom of loss
|
|
Visual acuity:
Ability to see details.
|
- Blurred vision
-
Squinting
- Adjusting items closer or further from body
- Diminished interest in reading or writing
|
|
Visual field:
What one can see by looking straight ahead (horizontal field = 160-180
degrees; vertical field = 120 degrees).
|
-
Loss in the lower horizontal field may mean tripping over objects, inability to work at a table, overlook a drop-off such as a curb
-
Loss in the upper horizontal field may mean hitting items with head or missing objects overhead
- Loss in either side of vertical field may mean sideswiping people and items close to left or right of body
|
|
Ocular motility (movement of the eyes):
Weak or shortened muscles of the eye affect movements.
|
- Excessive head movement
- Frequently loses place during reading and writing tasks
- Slow copying from board or other source
- Coloring or writing skills are not as expected for age
- Appears inattentive
|
|
Accommodation:
How the eye adjusts to maintain clear focus for objects in field of vision;
from near to far and from far to near.
|
- May have blurred vision
- May experience eyestrain
- May have difficulty following classroom activities; moving from board work to papers on desk
-
May not do well in games requiring catching objects, such as softball, ping pong, etc.
|
|
Visual perceptual skills:
These skills include discrimination, figure-ground, visual closure, visual
memory, spatial relationships, and eye-hand coordination.
|
- Experiences reversal of letters in reading and writing tasks
- Difficulty learning left from right
- Confuses likenesses and is unable to discern differences
- Difficulty remembering letters and numbers
- Difficulty coping from the board or overhead presentations
- Handwritten work and drawings are not as expected for age
-
Written work has poor spacing and is not on the lines
|
|
Color Blindness:
Inability to recognize colors. Most common color blindness is with the colors
red and green, but may affect perception of other colors as well.
|
- Will note that child does not respond to items of the color they can perceive
- May note the person can't read charts, graphs, or maps containing certain colors
|
|
Strabismus:
Commonly known as crossed eyes.
|
- One eye or both eyes may look in or out, or turn up or down
- The eye turning can occur all of the time or only sometimes, such as during stressful situations or illness
|
|
Conjunctivitis:
An inflammation of the conjunctiva, the thin, clear tissue that lies over the
eye and inside of the eyelid.
|
- Redness in the white of the eye or inner eyelid
- Increased amount of tears
- Thick, yellow discharge that crusts over the eyelashes, especially after sleep
- Green or white discharge from the eye
- Itchy eyes
- Burning eyes
- Blurred vision
- Increased sensitivity to light
|
Source:
Li, A. (2004). Classroom strategies for improving and enhancing visual skills
in students with disabilities. TEACHING Exceptional Children, 36(6), 38-46.
WebMD. Common eye problems. Retrieved
from http://my.webmd.com/content/article/81/96825.htm#7 on July
25, 2004.
