Electronic Devices for Low Vision Patients

1. Electronic Devices for Low Vision
Patients
Nilufa Akter
Optometrist (B.Optom, ICO, CMU)
Ispahani Islamia Eye Institute and Hospital

2. Electronic Device/Magnification system
 Electronic Devices/magnifying systems
come in many different varieties and
sizes, depending upon the task or
activity you want to perform.
 Includes:
1. a Camera system (for capturing images)
and a Monitor (to display the captured
images),. Ex. CCTV/Desktop Video
magnifier
2. Portable versions(PVM) : which you
can take along wherever you go.
Ex. Pebble HD, E-Bot
3. Mouse’-style devices
4. Head Mounted ex.(Vmax)

3.  Electronic Devices that works on the
principle of electronic magnification
(projection magnification).
 Magnification is achieved by projecting
or electronically changing an image so
that the new image has an increased
angular subtend at the eye.
• Enlargement of the image is measured
directly by dividing the image height
measured from the screen by the original
object height
• Eg: If the image of a 1 cm object produced
on the screen measures 9 cm, the
enlargement is 9×.
• This form of enlargement usually allows
longer working distances to be utilized

4. 1.Close Circuit Television/Electronic desktop
magnifier
 Is direct cable link between the camera imaging system and
the monitor viewing system (in contrast to broadcast
television), but this description generally refers to
surveillance devices and does not indicate the provision of
features, such as enlargement and contrast enhancement,
found in devices for the visually impaired.
 Consists of 3 major components:
1.camera
2.monitor
3. movable reading platform
• Best for pt. Having constricted VF, decreased VA, decreased
contrast sensitivity secondary to glaucoma, RP, ION.

5. -Video camera is directed at an object and image is
projected on TV monitor screen.
-Movable platform sits on a flat table/desk
-Magnification range: (3x to 100x) and
- Viewing modes with lighting, color, and contrast modes
for optimal visual assistance.

6. • The information is simply gathered in video real time,
and displayed in the monitor.
• The real time video magnification make the CCTV
magnifiers a great solution for
- writing and performing hands-on activities, -
- writing checks
- and intricate detail hobbies like needlepoint and
model building/painting.

8. Applied uses of CCTV:
1. Educational
2. Vocational
3.Recreational
4.Personal
5.Best for patient Having constricted VF,
decreased VA decreased contrast
sensitivity secondary to glaucoma, RP,
ION.

9. Advantages of CCTV:
1.Adjustable magnification
2.Wide range of magnification (4x to 100x)
3.Reverse Polarity available
4.Flexible working distance
5.Adjustable color and contrast
6.Binocularity possible
7.Adjustable field of view

10. Disadvantages of CCTV:
1.Bulky, not portable
2.Requires more training and practice
3.Difficulty of maintenance
4.More expensive

11. 2. Portable Video Magnifier(PVM)
• A portable digital magnifier is a device with a
camera on the underside that captures the
image of text, pictures, or other items, and a
monitor on the top side that displays the
image.

12. Important Features of Portable Digital Magnifiers:
Monitor sizes:
- range from 3.5 inches to 13 inches. Other available
monitor sizes are 4.3 inches, 5 inches, and 7 inches.
• Many models: with a high-definition (HD) camera
and monitor, while others still come with standard
resolution.
• Most models come with a protective carrying case.
• They are rechargeable, with an average battery life
of about three hours before needing to be
recharged. Recharging usually takes about three
hours.

13. Advantages of PVM
1. Used or taken anywhere
2. Provide helpful magnification, enhanced
contrast, and improved brightness, which is
important for many persons with low vision.
3. Less expensive than a CCTV.
4. Provide a fairly wide FOV, as compared with
many strong magnifiers.

14. Disadvantages of PVM
1. More expensive than most optical devices
2. Smaller field of view than a CCTV
3. It can be tiring to hold.
4. Some brands may show some distortion on
the edges, or the image may fade out in the
“false color” mode.

15. 3. Mouse’-style devices
• Consist of a camera usually
mounted on rollers in a small
hand-held case that can be
moved over the object of
interest
•Mouse-style devices are more
portable than conventional
stand-based EVES

16. 4. Head Mounted-VMax
• The V max is the next generation of a
head mounted assistance device that
address distance , intermediate and
near vision .
• It is an automatic focus system with the
range of magnification 0.8 to 20 times.
• One high resolution center colour
camera healed on head mounted unit.
• FOV of the camera is 47 degrees in
horizontal and 36 degree in vertical.
• Vmax requires no special fitting
procedure
-It can fitted over patient prescription
spectacles

17. Head Mounted Electronic device
MaxPort Magnifier with eyeglasses as display
unit
FlipperPort Magnifier
for distant viewing

18. ADVANTAGES of Head Mounted
1. System can use for variable distance
2. Wide range of magnification
3. Camera has color capability
4. Automatic focus capability
5.System is completely Portable
6. Easy to fit and operate

19. DISADVANTAGE OF VMAX
1. Control box and battery pack are heavy
2. System is expansive
3. System not wildly available

20. Others Electronic magnification system
Large Print Computers
• Can provide Enlarged print
on the screen through
either standardized and
dedicated software
• Software is also available to
provide speech for the
computer.

21. • Thank you