Bi0ptic Telescopes The patient, the decisions, and the training

1. Bi0ptic TelescopesThe patient, the decisions, and the training Ian L Bailey,OD, DSc, FAAO School of Optometry University of California, Berkeley. CA 94720-2020 ibailey@berkeley.edu

2. 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 veiling haze from headlights or bright light Adaptation(light/dark)adjusting to changes in light level Light sensitivityability to see in dim conditions

3. 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 Caution when considering statistical evidence 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

4. 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 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

5. What is the use of BiOptic Telescopes? BiOptic telescopes are Head mounted telescopesTypically magnification (for driving) = 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 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 can reduce field of view Brightness may be reduced Head and/or eye movements are required to interchange

6. Vision impairment and Nystagmus Congential Nystagmus Reduced visual acuity Normal contrast sensitivity Normal visual fields Astigmatism AlbinismReduced visual acuity Normal contrast sensitivity Normal visual fields Astigmatism, High refractive error (+) Some sensitivity to light AchromatopsiaReduced visual acuity Reduced contrast sensitivity (somewhat) Normal visual fields Poor color discrimination Photophobia Astigmatism, High myopia in some(Blue cone)

7. 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 tasks Especially in familiar areas, and other situations where need to read signs is minimal

8. BiOptic telescopes allow fine details to 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 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)

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

10. Projecting a telescope ring scotoma

11. Ring scotoma could be hazardous When viewing through telescope. There must be a substantial para-central field lossfrom the ring scotoma, IF -- the second eye is occluded OR -- if the second eye is functionally blind OR -- ifthere is a binocular telescope system BUT When viewing through telescope, there is no field loss Provided-- second eye does not have a telescope remains open can readily detect large peripheral objects does not have profound suppression

12. Some visual criteria for selecting patients for 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

13. Before prescribingOptometric 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

14. Some variations on usual more common testsVisual Acuity Reading efficiency for words and sentences 10 M 8.0 6.3 5.0 4.03.2 2.5 2.0 1.6 1.25 1.0 0.8 0.63 0.5 0.4 0.32 0.25 0.2 Word Reading 10 words each size Grade 3 word lists Sentences 60 characters MNRead Put your first name on this paper if you will help tomorrow Many people came to help us clean the place after the party

15. Some variations on usual more common testsVisual FieldsEffect of illumination Variable luminance backgrounds EITHER Plot fields OR Ask about letters visible on chart at different luminances RP, ARM etc fields change with luminance

16. Some variations on usual more common testsContrast SensitivityResponse Efficiency Tests Number search Flashing squares Output display Less than 2 mins per test Response time 2 measures at 24 contrasts vs Log CS

17. Some variations on usual more common testsUseful Field of View(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

18. Before prescribingEnsure 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

19. Before prescribingAdvising the patient Advise patients about their visual disabilities and functional relevance 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

20. Prescribing BiOptic Telescopes • Select telescope Magnification Design(Designs for Vision, Ocutech) Galilean,smaller, light weight, small field Keplerian,longer, heavier, larger field Focusfixed, adjustable, auto Exit Pupilsmaller 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)

21. PrescribingPositioning & Angling BiOptic Telescopes

22. 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 and then engage telescope) WHEN patient is proficient with telescope while a passenger THEN we issue DMV report form, patient applies for permit AND patient begins training with professional driving instructor

23. TrainingTest Cards for bioptic telescope evaluations

24. Dealing with theDepartment 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

25. Department of Motor VehiclesDriving test Driving test appointment with a “Driver Safety Referee” Driving test Longer course than usual Exposure to more visually-demanding driving tasks Night time drive test may be requested if patient wants to remove “no night driving” restriction

26. Department of Motor VehiclesIssue of a Driving License Unrestricted or Restricted License?? Special considerationsDriving 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 RequireBiOptic Telescope Special mirrors

27. Some Conclusions Visual acuity tasksmuch less important than visual field and contrast sensitivity tasks BiOptic Telescopesenable seeing of finer detail, when needed Visually impaired driversshould 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

28. Thank you! ibailey@berkeley.edu

29. For Europe POLICIES 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