The Role of Glare in Driving

Gary S. Rubin

Institute of Ophthalmology

London, UK

What is Glare?

Discomfort GlareDazzle, photophobia

Transient GlareGlare recovery

Reflected GlareVeiling reflection

Disability GlareVeiling luminance

Reflected Glare

What is Glare?

Discomfort GlareDazzle, photophobia

Transient GlareGlare recovery

Reflected GlareVeiling reflection

Disability GlareVeiling luminance

Starbursts

Halos

Flare

Glare Reduces Contrast

Glare Tests

Measures of visual function Increment threshold Acuity Contrast sensitivity

Glare Source Point source Extended glare Full-field glare

Clinical Glare Tests

Clinical Glare Tests

Clinical Glare Tests

Normal Age-Related Changes

Cornea - accounts for 30% Lens - accounts for 70%

Increased scatterBackscatter increases 16X from age 40 to 80Forward scatter probably increases even

faster Also reduced transmission

20X at shortest wavelengths from age 20 to 60

Only 1.2 X at longer wavelengths Fluorescence - at short wavelengths

Vitreous - Floaters and increased scatter

Glare and Aging

From Wolf (1960)

Ocular Pathology

Cataract - disability glare Macular Degeneration - glare recovery Retinitis Pigmentosa - discomfort glare Albinism - discomfort & disability glare

Glare and Cataract

0

10

20

30

40

50

-12 -6 0 6 12 18 24 30 36 42 48 54

Pre Op

Post Op

Fre

qu

en

cy

Letters Lost with GlareFrom Rubin, et al (1993)

Glare, Aging, and Driving

From Pulling, et al (1980)

Salisbury Eye Evaluation (SEE)

2520 residents of Salisbury, Maryland, selected from HCFA Medicare database

Eligibility 65-85 years of age MMSE score ≥ 18 Non institutionalized Able to travel to neighborhood clinic

26% of sample African American Ten-year longitudinal study

Components of SEE

Home interview (2 hours) Cognitive status screening test - MMSE Questionnaire on difficulty with visual activities (including

driving) - ADVS Medical history

Clinic exam (4 hours) Vision tests Visual attention test Eye exam Performance tests - reading, faces, IADLs, mobility Ocular photos

Examination of state driving records

Driving Evaluation

Past driving experience, miles driven, and recent driving limitations from Activities of Daily Vision Scale

Crashes (1991-1997) from Maryland Automated Accident Reporting System (MAARS) database

Glare Tests - BAT

Driving Study Population

Completed baseline examination 2,520 Refusals more likely to be older, female, and to

have less education Current drivers at baseline exam

1,974 Non-drivers more likely to be older, female, have

less education and more comorbid conditions Completed 2-year follow up (90%)1,780

Most of loss to follow up due to death

Measured Glare Sensitivity

20

25

30

35

66 68 70 72 74 76 78 80 82 84

Gla

re S

en

sit

ivit

y (

lett

ers

id

en

tifi

ed

)

Age

Self-Reported Glare Disability

50

55

60

65

70

75

80

85

90

66 68 70 72 74 76 78 80 82 84

Gla

re D

iffi

cu

lty

Sc

ore

Age

Objective vs Subjective Glare

0

20

40

60

80

100

12 18 24 30 36 42

Gla

re Q

ue

sti

on

na

ire

Sc

ore

Glare Sensitivity (letters identified)

Driving Behavior

Driving status 78% Current drivers 68% Drive only during day 52% Drive only in familiar areas

Miles driven last year Median = 5,200 (IQR = 2,000-10,000)

Crash involved 13% (243) during 1991-1997 4% (85) within 2 years following baseline exam

Predictors of Crash Involvement

0.6X 0.8X 1.0X 1.2X 1.4X 1.6X 1.8X

Acuity(per line)

Contrast Sens.(per line)

Glare Sens.(per line)

StereoacuityDefect

Visual FieldLoss

Odds of a Crash

Effect of Glare Sensitivity on Mileage

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

12 18 24 30 36 42

Lo

g M

ile

s D

riv

en

in

Pa

st

Ye

ar

Glare Sensitivity (letters identified)

Change in Mileage at Follow Up

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

12 18 24 30 36 42

Ch

an

ge

in

Lo

g M

ile

s D

riv

en

Glare Sensitivity (letters identified)

Glare and Night Driving

20

22

24

26

28

30

32

34

None Little Moderate Extreme Don't Drive

Gla

re S

en

sit

ivit

y (

lett

ers

id

en

tifi

ed

)

Night Driving Glare Problems

Glare and Night Driving Cessation

20

22

24

26

28

30

32

34

Never Stop Still Resume

Gla

re S

en

sit

ivit

y (

lett

ers

id

en

tifi

ed

)

Night Driving at 2-Year Follow Up

Glare Problems for Bioptic Drivers

Daytime Glare Nighttime Glare

* *

*Data on bioptic drivers kindly provided by A Bowers, Schepens Eye Research Institute, Boston, USA

0

10

20

30

40

50

60

70

80

Extreme Severe Moderate Mild None

Bioptic Drivers

SEE Study

Per

cen

t o

f P

arti

cip

ants

0

10

20

30

40

50

60

70

80

Extreme Severe Moderate Mild None

Bioptic Drivers

SEE Study

Per

cen

t o

f P

arti

cip

ants

Summary

Marked increase in glare sensitivity with age “Normal” aging Age-related pathology esp. cataract

Measured glare sensitivity is related to self-reported glare disability

Glare sensitivity does not predict crashes Glare sensitivity does predict changes in

driving behaviour Miles driven Driving at night

Is there anything we can do to reduce glare?

Neutral Density (sunglasses)

Polarizing Lenses

Anti Reflective Coatings

Without coating With coating

Anti Reflective Coatings

Without coating With coating?

The Future

Improving assessment of glare sensitivity Temporal factors Spatial factors

Reducing nighttime glare Reducing off-axis sources of light scatter Reduce scattering of short-wavelength light Cross polarization

Acknowledgements

Collaborators Sheila West and the SEE Project Team Ingrid Adamsons Walter Stark

Financial Support National Institute on Aging National Eye Institute Fight for Sight (UK)