David F. Hennessy PhDCalifornia Department of Motor Vehicles

Driving with the BiOptic Telescope in California

DMV Perspective

2004 International BiOptic Driving Conference

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California DMVBackground Info

BTL Licensing Policies & Procedures

1983 BTL Study Reports

Assessing Driving Fitness with Three-Tier Assessment System

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N = 23 million

Licensed Drivers in California

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California Department of Motor

Vehicles

N = 9,000 Employees

N = 168 Field offices

http://www.dmv.ca.gov/

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Research and Development Branch

N = 11 Research Staff

Develop and Evaluate Traffic Safety Programs

http://www.dmv.ca.gov/about/profile/rd/rdtoc.htm

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N= 400-500 California Drivers

validly licensed to use a Bioptic Telescopic Lens

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BTL Licensing Policies and Procedures

Report of Vision Examination

DiagnosisPrognosis

Vision-Related Driving Advice

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Visual Acuity with the Carrier Lens must be better than 20/200

Field of Vision must extend out to at least 75 degreesto the far right & far left

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Must have completed training in using BTL

Must pass DMV road test that includes freeway driving

Or

Accept restriction from freeway driving

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May not renew license by mail

Automatically restricted from nighttime driving - May be challenged

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Challenging restriction from nighttime driving:

Optometrist or ophthalmologistmust not have advised against night driving

Must pass nighttime road test

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BTL Controversy-California DMV Study

Janke, M. & Kazarian, G. 1983DMV Report #86

Janke, M. 1983Journal of Safety ResearchVolume 14, pp. 159-165

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Mean BTL Accident Rate Relative to General Driving Population – Janke 1983

Included:

229 BTL Drivers

Deceased

Suspended

Revoked

Not Renewed

185 BTL Drivers

Validly Licensed Only

All Accidents Raw Means 1.9* 1.6* Adjusted Means 1.5* 1.2 Fatal or Injury Accidents

Raw Means 2.9* 2.1 Adjusted Means 2.2* 1.7

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When the Janke 1983 analysis was confined to only validly licensed drivers, the adjusted mean accident rates for BTL drivers are not significantly higher than the general driving population.

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Two General Limitations of BTL Studies

Do not know whether BTL was actually worn or used when accident-involved

Amalgamation errors

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Ophthalmologists’ Waiting Rooms

50% Designated DriversBest Corrected VA = 20/20

50% PatientsBest Corrected VA=20/80

Overall Mean VA =20/40

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My conclusion?

The people sitting in ophthalmologists’ waiting rooms meet the California DMV 20/40 screening standard

Amalgamation Error

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Treating BTL drivers as though they are a functionally unitary group is no less an amalgamation error

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Congenital and Stable (ocular albinism )+Progressive (age-related macular degeneration)

= Amalgamation Error

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Reduced Central Vision Only(age-related macular degeneration)+Both Reduced Central Vision and Peripheral Fields(retinitis pigmentosa)

= Amalgamation Error

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Proficient in Spotting while keeping both eyes open+Minimally trained in the use of the BTL

= Amalgamation Error

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The Overall Mean accident rates for BTL drivers are artifacts produced by amalgamating entirely different subgroups.

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Conclusions based on the Overall Mean accident rates of BTL drivers are as misguided as concluding that people sitting in ophthalmologists’ waiting rooms meet the California DMV 20/40 screening standard.

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Assessing Driving FitnessWith

A Three-Tier Assessment System

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The overarching goal of the three-tier system is to keep drivers driving safely for as long as possible.