D3 & 4 - Low Vision Appliances Flashcards
Hand Held Magnifier:
Features
Simple magnifier
Single plus power biconvex lens
May be illuminate
Suitable for patients with AMD
Hand Held Magnifier:
Functional Benefits
Convenient for spot use
Common so psychologically acceptable
Compact, light weight & portable
Flexible task distance
Hand Held Magnifier:
Functional Limitations
Requires steady hands
Requires training
Subject to aberrations when used binocularly
Higher powers produce more aberrations with smaller FOV
Hand Held Magnifier:
Advice on use
Place on page and pull away until image is clear
Keep page flat
Steady eye strategy
Good illumination - angle poised lamp directly on page
Stand Magnifier:
Features
Simple magnifier
Cuff to set lens at correct distance
Internally illuminated
Can be available as one handle with changeable heads
Stand Magnifier:
Functional Benefits
Easy to maintain correct working distance
Stand may hold in place, allowing hands free
Internally illuminated, providing correct lighting
Stand Magnifier:
Functional Limitations
Fixed focus - specific specs may be required
Bulkier due to illumination
Stand Magnifier:
Advice on use
Place directly on page for focus
Use with reading specs
Keep page flat
Ensure batteries replaced frequently
Bar Magnifier:
Features
Simple loupe magnifier
Single plus lens
Acrylic or perspex
Can sit directly on age
May have line to aid tracking
Bar Magnifier:
Functional Benefits
Simple to use
No dexterity issues
Can maintain binocular vision
Cheap
Bar Magnifier:
Functional Limitations
Requires flat, firm surface
Narrow field of view
Bar Magnifier:
Advice on use
Position horizontally, directly on reading material
Use line to guide position
Use with near specs
When not in use, keep in case and out of direct sun
Pocket Magnifier:
Features
Simple magnifier
Single plus lens
May have multiple lenses in once case
Pocket size
Pocket Magnifier:
Functional Benefits
Small, portable and discreet
Lightweight
Psychologically and cosmetically acceptable
Cheap
Pocket Magnifier:
Functional Limitations
Small FOV
Not for prolonged use
Steady hand required
Pocket Magnifier:
Advice on use
Hold on material and bring away until clear
Use with distance specs
Bring closer to eye for increased FOV
For short tasks only
Prismatic Readers:
Features
High powered reading specs
Incorporate base IN prism to aid convergence
Usually half eye
Available up to +10 with 12 prims
Prismatic Readers:
Functional Benefits
Can maintain BV for near task with high adds
Half eye allows simultaneous distance vision
Hands free
Prismatic Readers:
Functional Limitations
Short working distance
Heavy and unattractive
Prismatic Readers:
Advice on use
Wear for specific near tasks only
Close working distance, start with page away and bring closer
Good illumination
Spectacle Mounted Telescope:
Features
Galilean system
Positive objective and negative eyepiece
Can have adjustable focus
Can be permanently fused, or clip on
Spectacle Mounted Telescope:
Functional Benefits
Variable working distance
Only reasonable solution for distance magnification
Hands free
Good depth of field
Spectacle Mounted Telescope:
Functional Limitations
Psychologically unacceptable
Heavy and bulky
Accurate centration is essential
Small field of view
Spectacle Mounted Telescope:
Advice on use
Use for specific tasks
Can adjust focus depending on working distance
Do not walk around when using
Requires good illumination
Monocular Hand Held Telescope:
Features
May be keplarian or galilean
Hand held and monocular
May clip to specs frame
May have adjustable focus
Monocular Hand Held Telescope:
Functional Benefits
Handheld, small and portable
Adjustable focus for range of working distances
Can clip on to specs for hands free
High mag available
Monocular Hand Held Telescope:
Functional Limitations
Stead hand required
Dexterity required
Only good for stationary objects
Monocular so not for prolonged use
Monocular Hand Held Telescope:
Advice on use
Adjustable eyepiece to focus
Use for specific spot tasks as mono use
Use with dominant eye
Hold steady, may require elbow support
Spectacle Mounted Magnifier:
Features
Plus powered lens mounted or clipped on specs
Patient’s own Rx can be glazed into housing specs
May be binocular or monocular
Spectacle Mounted Magnifier:
Functional Benefits
Good field of view
Coating and tint available to carrier lens
Hands free
BV can be maintained
Spectacle Mounted Magnifier:
Functional Limitations
May be psychologically unacceptable
Short working distance difficult to maintain
Accurate centration is essential
Poor illumination - extra required
Spectacle Mounted Magnifier:
Advice on use
Hold page away and bring closer
Use for specific near tasks
Do not walk around in when wearing
Good illumination required
Max TV Unit or Coil Distance Unit:
Features
Galilean telescope system
Adjustable focus for room distance use
Frosted objective lens housing eliminates reflections
Max TV Unit or Coil Distance Unit:
Functional Benefits
Simple and economic solution
Can be used for DV and some IV
Hands free
Max TV Unit or Coil Distance Unit:
Functional Limitations
Obvious - psychologically unacceptable
Heavy and uncomfortable for long wear
Requires dexterity for adjustments
Cannot compensate a high Rx
Max TV Unit or Coil Distance Unit:
Advice on use
Use for specific task
Demonstrate adjustment of working distance
Do not walk when wearing
Sheet Magnifier:
Features
Fresnel lens
Multiple concentric rings providing magnification
Can have foldable stand for support
Sheet Magnifier:
Functional benefits
Large field of view due to size
Cosmetically acceptable
Inexpensive
Light and easily portable
Sheet Magnifier:
Functional Limitations
Only available in low magnification
Posture sometimes difficult to maintain
Optically poor due to aberrations
Sheet Magnifier:
Advice on use
Hold on page and move away until clear
Use with near vision specs
Keep page flat
Good illumination
Chest Magnifier:
Features
Low magnification plus powered lens
Bracket and neck strap to support against chest
May have smaller, high mag segment
Chest Magnifier:
Functional Benefits
Constantly supported at the required working distance
Hands free
Low magnifications, means less aberrations and wider FOV
Inexpensive
Chest Magnifier:
Functional Limitations
Only low magnifications available
Move with patient, must stay still
Not ideal for patients with neck problems as heavy
Chest Magnifier:
Advice on use
Place at task then move up until clear
Position closer to eyer for wider FOV and read specs for increased mag
Use while seated
May require additional lighting
Hyperocular:
Features
Spectacle mounted magnification
Single high powered plus lenticular
Other ens occluded or frosted
Patient’s Rx can be included
Hyperocular:
Functional Benefits
Psychologically more accepted
Able incorporate prescription
Hands free
Large FOV due to short eye-mag distance
Hyperocular:
Functional Limitations
Short working distance difficult to maintain
Monocular only
Required good illumination due to short distance
Hyperocular:
Advice on use
Hold page in front of dominant eye and bring closer until clear
Use for specific tasks
Do not walk around wearing
Use good lighting - angle poised lamp
Tinted Overspectacles:
Features
Plano tinted/filter lenses
Wrap around design shields against disability glare
Provide UVA and UVB protection
Specific filters absorb certain wavelengths
Tinted Overspectacles:
Functional Benefits
Light weight
Able to use with own specs
May filter options
Wrap around shields from glare
Tinted Overspectacles:
Functional Limitations
Bulky and unattractive
Only of benefit in daylight
Depending on filter, can restrict driving
Tinted Overspectacles:
Advice on use
Wear over existing specs if required
Wear in bright conditions or if light problem
Do not wear when driving due to contrast filters
