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., Ph.D., Thomas Furness III., Ph.D.

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Problem Statement:

• Can the Virtual Retinal Display (VRD) be a helpful alternative low vision computer interface

• A testing protocol is needed to compare the two interfaces for low vision use

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

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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

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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

• Have low vision subjects compare the quality of images displayed between VRD and a CRT in terms of clarity and brightness

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Testing Site Setup:

• Testing conducted in a controlled environment at the Department of Services for the Blind

• 15 low vision subjects with variety of conditions

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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 luminance setting that matches the measured value of the white on black CRT

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

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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

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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

birdher

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Results: Reading SpeedMean 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

Mea

n P

erce

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

Mea

n P

erce

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

Mea

n P

erce

nt (

%)

All Subjects

Optical Causes

Retinal Causes

Mean Percent Improvement- Matched Luminance VRD vs. Red CRT

-20-10

01020304050

3.15 1.88 1.22 0.74

Character Size in Degrees

Mea

n P

erce

nt (

%)

All Subjects

Optical Causes

Retinal Causes

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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)

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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

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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)

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