bi0ptic telescopes prescribing decisions, the patient and the training ian l bailey, od, ms,...

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

bailey@spectacle.berkeley.edu

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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

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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

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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

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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

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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)

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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

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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

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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

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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

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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)

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For positioning For positioning && angling bioptic telescopes angling bioptic telescopesFor positioning For positioning && angling bioptic telescopes angling bioptic telescopes

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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

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Test Cards Test Cards for bioptic telescope evaluationsfor bioptic telescope evaluationsTest Cards Test Cards for bioptic telescope evaluationsfor bioptic telescope evaluations

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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

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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

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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

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Thank you!Thank you!Thank you!Thank you!

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bailey@spectacle.berkeley.edu