Bi 0 ptic Telescopes Prescribing decisions the patient

Bi 0 ptic Telescopes Prescribing 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

Basic 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 Adaptation (light/dark) Light sensitivity veiling haze from headlights or bright light adjusting to changes in light level ability to see in dim conditions

Should visually impaired people be allowed to drive? The Dilemma For denial to be justified Evidence 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

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

What is the use of Bioptic Telescopes? Bioptic telescopes are Head mounted telescopes Typically magnification = 2 x to 4 x 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 driving Signs, signals and other features with more small details can be seen at a longer distance than they otherwise could be Disadvantages Ring scotoma might reduce field of view Brightness may be reduced Head and/or eye movements are required to interchange

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

Bi. Optic telescopes allow fine details to 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 Bi. Optic telescopes only engaged intermittently for short periods when attending to signs (or other fine detail) BUT Potential danger when looking through telescope because part of visual field is occluded (RING SCOTOMA)

Illustration of RING SCOTOMA with 3 x telescope For a 3 x telescope Occluded area is 8 x larger than the area being magnified

Projecting a telescope ring scotoma

Ring 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 BUT When 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

Some visual criteria for selecting patients for bioptic telescopes for driving Best corrected Visual Acuity - 6/48 to 6/15 range (20/160 to 20/50) Telescope V A (M= 4 x or less) - 6/12 to 6/9. 5 range (20/40 to 20/32) Should not have more than a 3 x (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

Before prescribing Optometric 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

Before prescribing Ensure 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

Before prescribing Advising 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

Prescribing 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)

For positioning & angling bioptic telescopes

Training: Using 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

Test Cards for bioptic telescope evaluations

Dealing with the Department 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

Driving test with 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 consideration May 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

Issue of a Driving License by Department of Motor Vehicles If driving test is passed, the Driver Safety Referee may issue Unrestricted License OR a Restricted License Special 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

Summary 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

Thank you! bailey@spectacle. berkeley. edu