Transcript UNDERSTANDING VISION & VISUAL REHABILITATION IN THE

Managing the educational
support of learners with
low vision
Hazel Sacharowitz
[email protected]
WHAT IS LOW VISION?
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Partially sighted
Visually impaired
Visually disabled
Most misunderstood thought of as
“all or nothing”
WHAT IS LOW VISION?
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Disease or pathology in eye or along
visual pathway
No medical, surgical nor conventional
optometric treatment
Permanent irreversible loss
Is remaining vision!!!
Visual defect
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may be:
in the globe
the optic pathways
or visual cortex
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may be hereditary / congenital / acquired
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may affect:
visual acuity
visual field
colour perception
contrast sensitivity
dark adaptation
ocular motility and fusion
Where does LV fit in on a
scale?
20/20
NLP
Definition of low vision (WHO)
A person with low vision is one who has
impairment of visual function even after the
treatment and /or standard refractive
correction and has acuity of
less than 6/18 (20/60) to light
perception OR a visual field of less than
10 degrees
from the point of fixation, but who uses or is
potentially able to use vision for the planning
and/or execution of a task.
TREATMENT OPTIONS
1.
Magnification / minification –
a.
b.
c.
d.
2.
3.
distance
size
angular
projection
Eye movement skills
Alternative devices –
lighting, contrast, auditory
1. MAGNIFICATION
out of the “non-seeing”
part of the eye
into remaining “seeing”
part
Central vision loss
something
Central vision with magnification
something
something
1. Magnification:
a) Approach magnification
Halve distance, double acuity
b) Size magnification
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Increase size of task material:
• large print
• large digit watch
• enlarged TV/computer
• photostat larger!!
screen
c) Angular magnification
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Low vision devices
Not trial and error - systematic
Need full assessment to determine
amount of magnification
Individual approach unique for each
person
Task dependant
Angular magnification
DISTANCE
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Telescopes:
hand held
mounted
clip-on
focusable
auto-focus
Angular magnification
NEAR
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Hand magnifiers
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Stand magnifiers
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Spectacle mounted
d) Projection magnification
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Overhead projector
Slide projector
CCTV systems:
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Large amounts of variable
magnification
Contrast settings variable
Comfortable working distance
Variety of tasks
2. EYE MOVEMENT SKILLS
something
something
something
Magnification only
something
something
Magnification & eye movement
something
something
something
3. Non-optical
Lighting
b. Glare reduction
c. Contrast
d. Auditory
a.
a) LIGHTING
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Individual needs may vary
Children need well-lit rooms and play
areas – at home and school
Consider:
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Amount
Ability to control
Placement
Glare reduction
LIGHTING PLACEMENT
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Should not look into direct light
Teachers should be careful not to stand
in front of windows
Behind and on side of better seeing
eye
BE AWARE OF LIGHT/DARK
ADAPTATION TIME
b) GLARE
Is light that serves no purpose
Beware of light focused on glossy surfaces :
glass doors
 cabinets
 glossy paper – use non-glossy paper
 shiny desk tops – cover cloth/paper
 Computer – change polarity
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c) COLOUR CONTRAST
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Black against white
Light yellow against dark blue
Avoid using pastel colors next to
each other
Red often difficult to see - marking
CONTRAST
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Stairways –
tape/paint edges
Light switches
Telephone
Dials – hi-mark
Hand rails
Play surface
d) Auditory options
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Lap top or desk top computer – large
character display; synthetic speech –
JAWS / DOLPHIN programs…
Tape recorder
Read aloud as you write on
blackboard
MODIFICATION OF THE
CLASSROOM ENVIRONMENT
READING
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Appropriate use of low vision
devices
Use clearly printed reading
material – avoid poor photostat
copies
Black print on white or yellow
paper
Be aware of different colour text
and different font in some books
Enlarge print where applicable
Enlarge labels of diagrams rather
than diagram itself
WRITING
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Appropriate use of low
vision devices
Encourage use of black
felt tip or roller ball pens
rather than ballpoint or
pencil(B)
Use clearly lined white or
yellow paper with matt
finish
WRITING
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KHOKI PEN
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BLACK INK
PENCILS
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HB vs B
BLACKBOARD WORK
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Appropriate use of low
vision devices
Allow pupil to sit in front
row
Allow pupil to walk to
board to check information
Use the board in logical
sequence with adequate
spacing
BLACKBOARD WORK
continued
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Read aloud as you write
Keep board clean for
maximum contrast
Yellow or white chalk;
black koki pen
Be aware of glare
Provide clear copy of
text in advance
Don’t stand in front of
window
SEATING
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Encourage good posture –
note desk & chair height
with close working
distance
Sloping desk or bookstand
helpful
Seat child so to maximize
areas of vision – possibly
better sight on one side
than the other
CLASSROOM ENVIRONMENT
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Keep room free from
clutter particularly on
floor
Adequate lighting
Mark stairs with contrast
strips
Make glass doors visible
Avoid sharp protrusions
on furniture & fittings
Position displays at
appropriate height in
good light, no glare
THANK YOU …..
www.lighthouse.org
www.rnib.org
[email protected]
Tel: (011) 678 - 4438