The Role of Glare in Driving

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The Role of Glare in Driving

• Gary S. Rubin
• Institute of Ophthalmology
• London, UK

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What is Glare?

• Discomfort Glare
• Dazzle, photophobia
• Transient Glare
• Glare recovery
• Reflected Glare
• Veiling reflection
• Disability Glare
• Veiling luminance

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Reflected Glare
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What is Glare?

• Discomfort Glare
• Dazzle, photophobia
• Transient Glare
• Glare recovery
• Reflected Glare
• Veiling reflection
• Disability Glare
• Veiling luminance

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Starbursts
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Halos
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Flare
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Glare Reduces Contrast
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Glare Tests

• Measures of visual function
• Increment threshold
• Acuity
• Contrast sensitivity
• Glare Source
• Point source
• Extended glare
• Full-field glare

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Clinical Glare Tests
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Clinical Glare Tests
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Clinical Glare Tests
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Normal Age-Related Changes

• Cornea - accounts for 30
• Lens - accounts for 70
• Increased scatter
• Backscatter increases 16X from age 40 to 80
• Forward 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

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Glare and Aging
From Wolf (1960)
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Ocular Pathology

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

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Glare and Cataract
From Rubin, et al (1993)
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Glare, Aging, and Driving
From Pulling, et al (1980)
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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

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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

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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

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Glare Tests - BAT
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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

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Measured Glare Sensitivity
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Self-Reported Glare Disability
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Objective vs Subjective Glare
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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

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Predictors of Crash Involvement
Odds of a Crash
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Effect of Glare Sensitivity on Mileage
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Change in Mileage at Follow Up
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Glare and Night Driving
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Glare and Night Driving Cessation
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Glare Problems for Bioptic Drivers
Daytime Glare
Nighttime Glare


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

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Is there anything we can do to reduce glare?
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Neutral Density (sunglasses)
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Polarizing Lenses
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Anti Reflective Coatings
Without coating
With coating
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Anti Reflective Coatings
Without coating
With coating?
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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

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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)