Evaluation of a Scanned
Laser Display as an
Alternative Low Vision
Computer Interface
Conor Kleweno, Eric Seibel, Ph.D., Kyle
Kloeckner, Bob Burstein, Erik Viirre, M.D.,
1
Problem Statement:
• Can the Virtual Retinal Display (VRD)
be a helpful alternative low vision
computer interface
Introduction:
• Persons with low vision find computer use difficult with the standard computer display (CRT)
• A CRT is limited in brightness and contrast
• Low vision aid software can make computer use cumbersome
• The VRD may be a better alternative for low vision computer users
• The VRD uses a modulated, low power laser that displays an image directly onto retina using a two mirror scanning mechanism
Objectives:
• Design a testing protocol to compare the VRD
with a standard computer screen display (CRT)
• Conduct vision tests with low vision subjects
with different low vision conditions
• Determine if the VRD can be an effective
alternative low vision computer interface
• Use an acuity test to compare visual acuity
between the VRD and a CRT
Objectives (continued):
• Use a reading speed test to compare reading
performance between the VRD and a CRT
• Determine what types of low vision benefit
from VRD technology
4
Testing Site Setup:
• Testing conducted in a controlled environment at the Department of Services for the Blind
5
Four Test Conditions:
• A standard CRT with white on black contrast
• A standard CRT with red on black contrast
• The VRD with red on black contrast with a
luminance setting of one half of the measured
value of the white on black CRT
• The VRD with red on black contrast with a
Procedure:
• CRT acuity test used the white on black contrast
• VRD acuity test used the matched luminance setting
• Reading speed tests conducted at four character
angle sizes
• Three 20 second trials done at each character angle
size
• Subjects given oral questionnaire to obtain
subjective data on clarity and brightness of images
Acuity Test:
•Acuity tests conducted using the Landolt ring test
•Pointer arrows were used to assist subject in
locating image
•Acuity test range was 20/1128 to 20/67
Reading Speed Tests:
• Three words shown simultaneously to subject on PowerPoint slides as shown below
• Subject manually advanced through slides and orally read the words • Unrelated words used
• Reading speed evaluated as correctly read words per 20 second test • Box placed around words to help subject locate image
bird
her
state
Results: Reading Speed
Mean Percent Improvement- 1/2 Luminance VRD vs. White CRT-60 -40 -20 0 20 40 60
3.15 1.88 1.22 0.74
Character Size in Degrees
M ea n P er ce nt ( % ) All Subjects Optical Causes Retinal Causes
Mean Percent Improvement- Matched Luminance VRD vs. White CRT
-40 -20 0 20 40
3.15 1.88 1.22 0.74
Character Size in Degrees
M ea n P er ce nt ( % ) All Subjects Optical Causes Retinal Causes
Mean Percent Improvement- 1/2 Luminance VRD vs. Red CRT
-20.00 0.00 20.00 40.00 60.00
3.15 1.88 1.22 0.74
Character Size in Degrees
M ea n P er ce nt ( % ) All Subjects Optical Causes Retinal Causes
Mean Percent Improvement- Matched Luminance VRD vs. Red CRT
-20 -10 0 10 20 30 40 50
3.15 1.88 1.22 0.74
Character Size in Degrees
Results:
Visual acuity
Subjective responses
Did the CRT or VRD Produce Better Visual Acuity?
Same (3)
VRD (6)
CRT (5)
Which Display Was Perceptually Clearer?
VRD (10)
CRT (2) Same (2)
Which Display Was Percptually Brighter?
VRD (11) Same (2) CRT (1)
Discussion:
• VRD increased visual acuity and reading speed in some low vision subjects
• Overall, subjects with low vision conditions due to optical causes benefited most from VRD
• 64% of subjects had equal or better visual acuity with the VRD • 71% of subjects found VRD images clearer
• 79% of subjects found VRD images brighter
• In general, subjects disliked red on black contrast
• The testing protocol allowed a valid comparison between the two displays • More testing is planned to further define types of low vision that will benefit
from VRD
Acknowledgements:
• Human Interface Technology (HIT) Lab
• Howard Hughes Medical Scholar Summer Program
• John Olson and the Washington State Department of Services for the Blind, Seattle, Washington
• National Science Foundation (Grant number DMI-9801294)
