Course: Visual Assessment of Children: The Orthoptist Role
Presented on Wednesday 9 February 2005
Low Visual Aid Assessment
Morag McGillivray
Presented on Wednesday 9 February 2005
- Who?
- What?
- Where?
- Why?
Moray Low Vision Service
?to provide the people of Moray with an efficient, effective low vision
service that enabled
individuals experiencing a visual loss which couldn?t
be corrected by conventional means to
make optimum use of their remaining
vision...
- Accept
- Adapt
- Achieve
Low Visual Aids
- Types of tasks at home, work or school. (near, intermediate, distance)
- Desired outcome
- Physical limitations
- Non-optical aids such as lighting etc.
Size matters!
X3.9 Larger field of vision, longer working distance
X5.4 Smaller field of vision, shorter working distance.
The Low Vision Assessment Preliminary tests include?
- Ophthalmic examination
- Refraction Functional vision assessment / orthoptic assessment
- Contrast Sensitivity
Contrast Sensitivity
?the ability of the visual system to distinguish between an object and its background...
Text contrast levels
- Newsprint 60-70%
- Paperback books 75%
- Laser printers 94%
Testing Contrast Sensitivity
Taking a history...
- Are there specific educational needs?
- Does the student work with a visual impairment teacher?
- Do they use large print workbooks?
- Can they see the blackboard / whiteboard?
- Are there computer requirements?
- Is there access for computer technology adapted for visual impairment?
Keeler ?A? Chart
Hand - held magnifiers
- Portable
- Relatively inexpensive
- Wide range of powers (x1.7 to x8)
- Unsuitable when hand tremor present.
- Most common type of aid used by school children.
- LED light source provides brighter illumination and clearer, whiter light.
- Unobtrusive
- Wide range of powers (x3 to x11)
Stand Magnifiers
- Hands free use.
- Wide range of powers (x3 to x20)
- Can be used in conjunction with a pencil / pen
- Bulky
- Can be difficult to get sufficient lighting.
- Shadowless light close to the page
- LED light source
- Lacks street cred!
Dome magnifiers
- Sit directly on reading surface
- Always in focus
- Available in wide range of shapes and sizes
- Limited range of power, typically x1.7
Bar magnifiers
- Semi-cylindrical lenses
- Magnify one line of print at a time
- Reduces tracking across page.
- Limited power
- Distorted, stretched image.
Hands free magnification
- Ideal for arts and craft
- Large lens
- Low power (x1.7)
- Can be bulky
Spectacle mounted magnifiers
- Hands free use
- Wide range of power
- Improved design
- Reduced lens thickness
- Short working distance
Telescopes
- Designed for intermediate and distance magnification.
- Lightweight
- Easy to focus
- Must only be used when stationary.
- Can take time to master art of focusing.
Electronic video magnifiers
The 10 Commandments
- Thou shalt throw away the rule book.
- Thou shalt see the child as a whole person and not simply a pair of eyes.
- Thou shalt always remember the 3 A?s?accept, adapt, achieve.
- Thou shalt seek advice from those who know the child best.
- Thou shalt involve the child?s parents whenever possible.
- Thou shalt not be afraid to experiment.
- Thou shalt keep it simple.
- If at first you don?t succeed thou shalt try again ? and again ?
- Thou shalt never underestimate the power of peer pressure.
- Thou shalt,
wherever possible, provide a spare aid as sometimes the dog eats more
than
just their homework.