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Bi0ptic TelescopesBi0ptic Telescopes The patient, the decisions, and the trainingThe patient, the decisions, and the training

Ian L Bailey, OD, DSc, FAAOSchool of Optometry

University of California, Berkeley. CA 94720-2020

ibailey@berkeley.edu

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Basic Vision Functions and DrivingBasic Vision Functions and Driving

Visual acuityreading 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

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Should 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

Caution when considering statistical evidenceAssociations 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 Safety Risk of accidents, Interference with

traffic flow

Individual's Independence Travel 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?

Licensing Authorities (DMV’s) have the responsibility to test driving abilities, to allow or deny licensure,and to impose any restrictions

They may consider Special driving testsPast driving experience Anticipated driving needsCausative 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?

BiOptic telescopes areHead mounted telescopes Typically magnification (for driving) = 2x to 4xArranged 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 can reduce field of view Brightness may be reducedHead and/or eye movements are required to interchange

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Vision impairment and NystagmusVision impairment and NystagmusCongential Nystagmus Reduced visual acuity

Normal contrast sensitivity Normal visual fields Astigmatism

Albinism Reduced visual acuityNormal contrast sensitivityNormal visual fields Astigmatism, High refractive error (+) Some sensitivity to light

Achromatopsia Reduced visual acuity Reduced contrast sensitivity (somewhat) Normal visual fields Poor color discrimination Photophobia Astigmatism, High myopia in some (Blue cone)

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Is seeing fine detail important to driving?Is seeing fine detail important to driving?

Yes!Reading signs (freeway signs, street signs, warnings, parking, house numbers, building signs)

Traffic signs size and location usually designed on assumptions that drivers will have a visual acuity of 20/40 (6/ 12 or 0.5)

But!Reading signs, or attending to fine details required for short-term and infrequent driving tasksEspecially 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

A driver who obtains 20/40 or better through telescope,should be able 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

OBJECT SPACE Ring 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 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 Z A B C D E F G H I J K L M N O

y z a b c d T 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 scotoma

20m = 65 ft 1.8 sec @ 40 km/hr (25 mph) 0.7 sec @ 100 km/hr (63 mph)

3x 3x

Keplerian GalileanREAL WORLD Object space

SUBJECT SEES Image space

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Ring scotoma could be hazardousRing scotoma could be hazardous

When viewing through telescope. There must be a substantial para-central field loss from the ring scotoma,

IF -- the second eye is occluded OR -- if the second eye is functionally blind

OR -- if there is a binocular telescope system

BUTWhen viewing through telescope, there is no field lossProvided -- second eye does not have a telescope

remains open can readily detect large peripheral objects

does 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

Best corrected Visual Acuity - 20/160 to 20/50 range (6/48 to 6/15)

Telescope V A (M= 4x or less) - 20/40 to 20/32 range (6/12 to 6/9.5)

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 20/400 or better (6/120)

Second eye should not have profound suppression

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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 timeVision in clutterDivided attention

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Some variations on usual more common testsSome variations on usual more common tests Visual Acuity Visual Acuity Reading efficiency for words and sentencesReading efficiency for words and sentences

pretty only loves side along visits cold months smiled part ride about begins work today ready called draw tired jump

Put your first name on this paper if you will help tomorrowMany people came to help us clean the place after the party

Word Reading10 words each sizeGrade 3 word lists

Sentences60 charactersMNRead

10 M8.06.35.04.03.22.52.01.61.251.00.80.630.50.40.320.250.2

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Some variations on usual more common testsSome variations on usual more common tests Visual FieldsVisual Fields Effect of illuminationEffect of illumination

Variable luminance backgrounds

EITHER Plot fields

OR Ask about letters visible on chartat different luminances

RP, ARM etc fields change with luminance

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Some variations on usual more common testsSome variations on usual more common tests Contrast SensitivityContrast Sensitivity Response Efficiency TestsResponse Efficiency Tests

Number search Flashing squares

Output display Less than 2 mins per testResponse time 2 measures at 24

contrasts vs Log CS

1.81.61.41.21.00.80.60.40.20.00

1

2

3

log CS

Res

pons

e (s

ecs)

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Some variations on usual more common testsSome variations on usual more common tests Useful Field of ViewUseful Field of View (UFOV)(UFOV)

Test patient’s ability to respond to peripheral stimuli

Delayed reaction times for peripheral visual stimuli

Failure to see brief, peripheral visual stimuli (i.e., reduced measured visual field)

When there is Divided visual attention Visual clutter Multi-tasking

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Before prescribingBefore prescribingEnsure 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 outdoorsstationary observer - stationary object of regardstationary observer - moving object of regardmoving observer - stationary object of regardmoving observer - moving object of regard

Real world location and viewing of targets in visual clutterfirst locate the target object, and then engage telescope

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Before prescribingBefore prescribing Advising the patientAdvising the patient

Advise patients about their visual disabilities and functional relevance

Bioptic telescope does not ensure ability to pass driving testBioptic telescopes do not restore vision to normalEven with bioptic telescopes, they remain at a visual disadvantage

Need to drive with extra cautionShould have companion drive when possible

Need practice in viewing with bioptic telescope systemNeed 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

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Prescribing 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 to vary height, lateral position and angle

• Determine lens powers for telescope and carrier lens • Select characteristics of carrier lens (SV, bifocal, tint)

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PrescribingPrescribingPositioning Positioning && Angling Angling BiOptic TelescopesBiOptic Telescopes

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Training: 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 and then engage telescope)

WHEN patient is proficient with telescope while a passengerTHEN we issue DMV report form, patient applies for permit AND patient begins training with professional driving instructor

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TrainingTraining

Test 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

• Appointment with a “Driver Safety Referee”• Present vision report that includes information

VA with and without telescopeFields, contrast sensitivityCausative 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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Department of Motor VehiclesDepartment of Motor Vehicles Driving test Driving test

Driving test appointment with a “Driver Safety Referee”

Driving test Longer course than usualExposure to more visually-demanding driving tasks

Night time drive test may be requested if patient wants to remove “no night driving” restriction

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Department of Motor VehiclesDepartment of Motor Vehicles Issue of a Driving License Issue of a Driving License

Unrestricted or Restricted License??Special considerations Driving skill tests Causal disease

Driving experience Visual abilitiesDriving record Extent of vision lossDriving need Prognosis, stabilityAnticipated driving Variability of vision Sensory motor disabilities Other visual disabilities

Special constraints Monitor Accidents ViolationsIncrease frequency Renewal Vision reportsDriving testsRestrict Time of day Visibility conditions Routes PurposeDistance from home Vehicle categoryRequire BiOptic Telescope Special mirrors

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Some ConclusionsSome Conclusions

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 opportunity to demonstrate ability to drive safely

It can be reasonable to specify definite limits OPINIONS :New California limit -better than 20/200 (6/60) -is acceptable

No driving with hemianopia is reasonable

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Thank you!Thank you!

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O p t o m e t r y ibailey@berkeley.edu

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For EuropeFor EuropePOLICIES TO DEMAND BiOptic telescope is a corrective lens system Telescope must allow visual acuity of 6/12 (20/40 or 0.5)

Telescope must be before one eye only BiOptics are to be used with two eyes open so, relevant visual field test is with both eyes open

COMPROMISES TO ACCEPT OR CONCEDE Vision report every 5 years (at least) Maximum mag = 4x, or without TS, VA > 6/48 (20/160 or 0.125)

Driving should be conditional on wearing telescope Initial license should be for daytime use only Night driving cannot be considered until 3 years experience