4.2.2 LV Flashcards
what is a Galilean telescope
one convex( obj lens) and one concave eye piece lens
light parallel in and parallel out
image errect
what is astronomical/keplerians
2 convex lens
light parallel in and parallel out
image inverted - correct with prism
why use telescopes as LVA
used for distance tasks
provide magnification without having to get any closer to the object
Why use near the tescopes
- provides longer wd
supplementary lenses in galilean - has extra plus Lens onto and add extra amount of plus to objective lens to compensate for close working distance
- increase lens separation in astronomical
- this reduces working distance
- variable focus
pros of NV telescope
longer WD
cons of nv telescope
cosmesi
weight ( esp astronomical)
smaller fov
limited depth of focus
what are examples of distance telescopes
galilean 3-4x mag
clip on 3x mag
spectacle mounted 3 4x
keplarian 6x
what are examples of near telescope
galilean 2.5x mag
keeler LVA 22- up to 8x
how can you adapt a phone
bigger - larger text , zoom in , magnifier setting or app
contrast - bold text , invert colours , colours contrast
brightnesss- increase it , increase saturation
audio - tex to voice, audio desciption
what are complex lv aids
- Spectacle mounted telescopes
- Field expanders
- CCTVs
- X-Y table
- Television readers
- Head mounted
- Portable
- Intraocular telescope (not really required but may impress assessor)
CCTV ADVANTAGES
- CTV Advantages:
- High Mag - up to 70X, zoom in & out
- Contrast reversal & enhancement - enhances from 70 to 100%, reverse polarity, colour options & margins to use as typoscope
- Better posture - not looking downward
- Socially acceptable - at work & school
- Binocular
- Good depth of field
CCTV DISADVANTAGES
- Expensive!
- Hard to use - need practice for all the controls!
- ## Not very portable although TV readers are
WHAT Are non optical aids
- typoscope
tactile( place on jars for px to differentiate which jar is for what)
bumpons
braille
talking devices ( audible liquid level indicator. talking tins/clocks)
what are apps
be my eyes
identifi ( app that looks at any image and relays verbally what it is)
voice over
google maps
ebooks audio books
where can you get lv
RNIB, Low vision clinic
Macular society
Eschenbach is a German company that specialises in LVAs that are premium quality. Very good to suggest to sight impaired patients
Desktop magnifiers, or CCTV’s (closed circuit televisions), are ideal for low vision users. They use a camera to project a magnified image onto a monitor. T
