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U C BO p t o m e t r y
Bi0ptic TelescopesBi0ptic TelescopesPrescribing decisions, the patient and the trainingPrescribing decisions, the patient and the training
Bi0ptic TelescopesBi0ptic TelescopesPrescribing decisions, the patient and the trainingPrescribing decisions, the patient and the training
Ian L Bailey, OD, MS, FCOptom, FAAO
School of Optometry
University of California, Berkeley. CA 94720-2020
U C BO p t o m e t r y
Basic Vision Functions and DrivingBasic Vision Functions and DrivingBasic Vision Functions and DrivingBasic Vision Functions and Driving
Visual acuity reading signs, seeing detail
Contrast sensitivity seeing larger objects, borders, textures
Visual fields seeing things to the side
Color vision ability to see traffic signals, warning lights
Glare veiling haze from headlights or bright light
Adaptation (light/dark) adjusting to changes in light level
Light sensitivity ability to see in dim conditions
U C BO p t o m e t r y
Should visually impaired people be allowed to drive? Should visually impaired people be allowed to drive?
The DilemmaThe DilemmaShould visually impaired people be allowed to drive? Should visually impaired people be allowed to drive?
The DilemmaThe Dilemma
For denial to be justifiedEvidence of individual incompetence
Evidence (associations) of highly elevated risk
Strong prima facie argument for highly elevated risk
Principles
Associations describe trends - they are not rules
Higher crash rates for a given group is insufficient,
by itself, to disqualify all members of that group
Public SafetyRisk of accidents, Interference with
traffic flow
Individual'sIndependenceTravel for work, or social participation
U C BO p t o m e t r y
Should visually impaired people be allowed to drive? Should visually impaired people be allowed to drive? Should visually impaired people be allowed to drive? Should visually impaired people be allowed to drive?
Licensing Authorities (DMV’s) have the responsibility to allow or deny licensure, and to impose restrictions
They may consider Special driving tests
Past driving experience
Anticipated driving needs
Causative disorder
Other health issues (sensory, motor, cognitive)
They may impose Closer monitoring of driving record
More frequent vision and driving tests
Restrictions on routes, time of day, etc.
Restricted vehicle categories, speed
They may require Bioptic telescopes
U C BO p t o m e t r y
What is the use of Bioptic Telescopes?What is the use of Bioptic Telescopes?What is the use of Bioptic Telescopes?What is the use of Bioptic Telescopes?
Bioptic telescopes are
Head mounted telescopes Typically magnification = 2x to 4x
Arranged to allow easy interchange from viewing with and without the telescope
Bioptic telescopes magnify Enable distant details to been seen to be seen more easily.
Advantages for drivingSigns, signals and other features with more small details
can be seen at a longer distance than they otherwise could be
DisadvantagesRing scotoma might reduce field of view
Brightness may be reduced
Head and/or eye movements are required to interchange
U C BO p t o m e t r y
Is seeing fine detail important to driving?Is seeing fine detail important to driving?Is seeing fine detail important to driving?Is seeing fine detail important to driving?
Yes!Reading signs (freeway signs, street signs, warnings, regulations, house numbers, building signs)
Traffic signs size and position usually designed on assumptions that
drivers will have a visual acuity of 6/12 (20/ 40 or 0.5)
But!Reading signs or attending to fine details required for
short-term and infrequent driving tasks
Especially in familiar areas, and other situations where need to read signs is minimal
U C BO p t o m e t r y
BiOptic telescopes allow fine details BiOptic telescopes allow fine details to be seen from a longer distanceto be seen from a longer distance
BiOptic telescopes allow fine details BiOptic telescopes allow fine details to be seen from a longer distanceto be seen from a longer distance
If a driver obtains 20/40 or better through telescope,
he may be enabled to read roadway signs etc from the intended distance
BiOptic telescopes only engaged intermittentlyBiOptic telescopes only engaged intermittently
for short periods when attending to signs (or other fine detail)
BUTPotential danger when looking through telescope because part of visual field is occluded (RING SCOTOMA)
U C BO p t o m e t r y
Illustration of RING SCOTOMA with 3x telescope Illustration of RING SCOTOMA with 3x telescope Illustration of RING SCOTOMA with 3x telescope Illustration of RING SCOTOMA with 3x telescope
OBJECT SPACERing scotoma is blue area blocked by the 3x enlargement of yellow area
IMAGE SPACE 3x enlarged yellow area occludes a substantial area
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x y zA B C D E F G H I J K L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O
y z a b c dT U V W X 19 20 21 22 y z a b c d
For a 3x telescope Occluded area is 8x larger than the area being magnified
U C BO p t o m e t r y
Projecting a telescope ring scotomaProjecting a telescope ring scotomaProjecting a telescope ring scotomaProjecting a telescope ring scotoma
20m = 65 ft
1.8 sec @ 40 km/hr (25 mph)
0.7 sec @ 100 km/hr (63 mph)
3x 3x
Keplerian GalileanREALWORLD
Object space
SUBJECT SEES
Image space
U C BO p t o m e t r y
Ring scotoma could be hazardousRing scotoma could be hazardousRing scotoma could be hazardousRing scotoma could be hazardous
When viewing through telescope. There would be
a substantial para-central field loss from the ring scotoma,
IF -- the second eye was occluded
OR -- if the second eye was functionally blind
OR -- if there was a binocular telescope system
BUTWhen viewing through telescope, there is no field loss
Provided -- second eye did not have a telescope
was open
could readily detect large peripheral objects
did not have profound suppression
U C BO p t o m e t r y
Some visual criteria for selecting patients Some visual criteria for selecting patients for bioptic telescopes for drivingfor bioptic telescopes for driving
Some visual criteria for selecting patients Some visual criteria for selecting patients for bioptic telescopes for drivingfor bioptic telescopes for driving
Best corrected Visual Acuity - 6/48 to 6/15 range (20/160 to 20/50)
Telescope V A (M= 4x or less) - 6/12 to 6/9.5 range (20/40 to 20/32)
Should not have more than a 3x (0.5 log units) reduction in CS
Should not have significant field defects
Telescope before one eye only (better reading eye)
Second eye should have VA of 6/120 or better (20/400)
Second eye should not have profound suppression
U C BO p t o m e t r y
Before prescribingBefore prescribingOptometric consideration of visual abilitiesOptometric consideration of visual abilities
Before prescribingBefore prescribingOptometric consideration of visual abilitiesOptometric consideration of visual abilities
Hard numbers on Visual acuity
Contrast sensitivity Visual fields
Evaluate as needed Color vision Glare
Adaptation (light/dark)
Light sensitivity
Consider Motor and mental agility Reaction time
Vision in clutter
Divided attention
U C BO p t o m e t r y
Before prescribingBefore prescribing
Ensure good skill using telescopesEnsure good skill using telescopesBefore prescribingBefore prescribing
Ensure good skill using telescopesEnsure good skill using telescopes
Hand held telescope - magnification equal to, or stronger, than planned bioptic
Achieve 20/40 with telescope
Efficient spot viewing - both indoors and outdoors
stationary observer - stationary object of regard
stationary observer - moving object of regard
moving observer - stationary object of regard
moving observer - moving object of regard
Real world location and viewing of targets in visual clutter
first locate the target object, and then engage telescope
U C BO p t o m e t r y
Before prescribingBefore prescribing Advising the patientAdvising the patient
Before prescribingBefore prescribing Advising the patientAdvising the patient
Bioptic telescope does not ensure ability to pass driving test
Bioptic telescopes do not restore vision to normal
Even with bioptic telescopes, they remain at a visual disadvantage
Need to drive with extra caution
Should have companion drive when possible
Need practice in viewing with bioptic telescope system
Need supervised training using bioptic telescope for driving
If no driving experience, likely to need more instruction than usual from
a professional driving instructor
The DMV makes the final decisions
U C BO p t o m e t r y
Prescribing Bioptic TelescopesPrescribing Bioptic TelescopesPrescribing Bioptic TelescopesPrescribing Bioptic Telescopes
• Select telescope Magnification
Design (Designs for Vision, Ocutech)
Galilean, smaller, light weight, small field
Keplerian, longer, heavier, larger field
Focus Fixed, adjustable, auto
Exit Pupil smaller or larger than pupil
• Select frame Suitable for telescope mounting
Sturdy and comfortable
Adjustable nose pads to vary height and lateral position
• Determine lens powers for telescope and carrier lens
• Select characteristics of carrier lens (SV, bifocal, tint)
U C BO p t o m e t r y
For positioning For positioning && angling bioptic telescopes angling bioptic telescopesFor positioning For positioning && angling bioptic telescopes angling bioptic telescopes
U C BO p t o m e t r y
Training: Training: Using a Bioptic TelescopeUsing a Bioptic TelescopeTraining: Training: Using a Bioptic TelescopeUsing a Bioptic Telescope
Rehabilitation Staff
Five to fifteen lessons of 30 minutes.
Home practice after each lesson Begin practice indoors with flash cards, Practice outdoors while walking (include traffic signs)
Practice while a passenger in a car
(residential, business and freeways)
(locate signs, signals, landmarks, engage telescope)
WHEN patient is proficient with telescope while a passenger
THEN we issue DMV report form
AND patient begins training with professional driving instructor
U C BO p t o m e t r y
Test Cards Test Cards for bioptic telescope evaluationsfor bioptic telescope evaluationsTest Cards Test Cards for bioptic telescope evaluationsfor bioptic telescope evaluations
U C BO p t o m e t r y
Dealing with theDealing with the Department of Motor VehiclesDepartment of Motor Vehicles
Dealing with theDealing with the Department of Motor VehiclesDepartment of Motor Vehicles
• Appointment with a “Driver Safety Referee”• Present vision report that includes information
VA with and without telescope
Fields, contrast sensitivity
Causative eye disease or disorder, stability and prognosis
May be considered a learner’s permit
THEN the patient takes the written test
THEN driving permit may be issued
LATER, patient takes drive test
U C BO p t o m e t r y
Driving test Driving test with Department of Motor Vehicleswith Department of Motor Vehicles
Driving test Driving test with Department of Motor Vehicleswith Department of Motor Vehicles
Driving test appointment with a “Driver Safety Referee”
Driving test
Longer course than usual
Exposure to more visually-demanding driving tasks
Individual considerationMay consider experience and need
May impose restrictions - times, routes, use of bioptics, etc
Night time drive test may be requested
if patient wants to remove “no night driving” restriction
U C BO p t o m e t r y
Issue of a Driving License Issue of a Driving License by Department of Motor Vehiclesby Department of Motor Vehicles
Issue of a Driving License Issue of a Driving License by Department of Motor Vehiclesby Department of Motor Vehicles
If driving test is passed, the Driver Safety Referee may issue
Unrestricted License OR a Restricted LicenseSpecial considerations Driving skill tests Causal disease
Driving experience Visual abilities
Driving record Extent of vision loss
Driving need Prognosis, stability
Anticipated driving Variability of vision Sensory motor disabilities Other visual disabilities
Special constraints
Monitor Accidents Violations
Increase frequency Renewal Vision reports
Driving tests
Restrict Time of day Visibility conditions Routes Purpose
Distance from home Vehicle category
Require Bioptic telescope Special mirrors
U C BO p t o m e t r y
SummarySummarySummarySummary
Visual acuity tasks much less important
than visual field and contrast sensitivity tasks
Bioptic telescopes enable seeing of finer detail
when needed
Visually impaired drivers should be given an
opportunity to demonstrate ability to drive safely
It can be reasonable to have definite limits OPINIONS :New California limit of better than 20/200 (6/60) is acceptable
No driving with hemianopia is reasonable
U C BO p t o m e t r y
Thank you!Thank you!Thank you!Thank you!
U C BO p t o m e t r y