Electronic Magnification And Tablet/ Smart Phone Apps Flashcards
CCTV
Closed circuit TV
-aka video magnifier
In its simplest form consist of a video camera and a monitor
Camera on some models can be adjusted for distance and near
Advantage of CCTVs
- can enhance contrast of the printed material
- can provide reversed contrast for patients with glare sensitivities
- can enlarge beyond the capabilities of optical magnifiers
- allows for increased working distance and BV viewing
- relatively larger aberrations free FOV
Reasons CCTVs are indicated for children
- to enable a parent to read yo a young child
- to facilitate a love for reading and learning
- to decrease the stress and strain of homework burden
- to view the board at school
Disadvantage of CCTV
Cost
- full-size (2300-3200)
- portable (1200-2000)
- handheld (300-900)
Need for power source (many have rechargeable batteries)
Size
Psychological-must be “ready”
Magnification by a CCTV
M=image size on screen/object size (RSM)
Mtotal=RDMxM(CCTV)
Fe=F2xM(CCTV)
F2 is the add or accommodation
The patient reads 0.2/3.2M with her BC and a +5 add. She wants to read her family bible. You measure the print and it is 3mm tall for a lower case “e”. What is the M size for the print in her bible?
3/1.47=2.07M
The pateitn reads 0.2/3.2M with her best correction and a +5 add. She is a -2.25D myope and used to read with her glasses off. You plan to show her a CCTV to use without correction. How far must she postion her eyes from the screen
1/2.25=0.444
A patient reads 0.2/3.2M with her best correction and a +5 add. What total mag by is needed in order for her to just read her family bible (remember the print was 3mm tall)?
M=3.2./2M=1.6x
The patient reads 0.2/3.2M with her best correction nand a +5 add. She is a -2.25D myopie and uses the CCTV uncorrected. What mag by the CCTV itself is needed in order for her to just read her family bible?
M=3.2/2=1.6x
M=rf
1.6=.2F
F=8
Fe=F2xM(CCTV)
8=2.25xM(CCTV)
3.56=M(CCTV)
M=RDMxM(CCTV)
- 6=(.2/.44)M(CCTV)
- 56=M(CCTV)
How large will the letters be on screen? For the Bible
Bible print was 3mm tall
3mm x 3.56=10.68mm
1.45/1M=10.68/x
X=7.36M
Clearview and Merlin
What’s new
- flat panel, HD monitors
- up to 61m
- prices not increasing
What’s the same
- autofocus
- color
- X-Y table
- articulating monitor arm
Acrobat, multiethnic-view and onyx CCTV
- newer generation
- 1 piece
- easily moved
- distance and near
- full function CCTV
- easier to write under
- requires external illumination
- can be used in combo with E readers or iPads
Laptop compatible CCTV
Magnilink student
Flick
Pebble and pebble mini CCTV
- $295 and $595
- offer complete probability
- enhances contrast and provides mag
- rechargeable Battery
Head mounted CCTV
ESight
