Driving With BiOptic Telescopic Lens Systems
A presentation by Charles P. Huss, C.O.M.S
This paper was presented at The Eye and The Auto International Forum in June 2001 at the Daimler Chrysler Technology Center in Auburn Hills MI. The Eye and The Auto is a research project of the Detroit Institute of Ophthalmology (DIO). Thirty-two of the world's leading authorities in vision and vision related research were brought to the metropolitan area of Detroit as guests of the DIO to discuss the relationship of vision and safe operation of motorized vehicles. For more information, go to http://www.eyeson.org and click-on The Eye and The Auto, under Research. The proceedings are available for purchase.
Index to the Presentation
To Find Out More...
0.) The Presentation
Currently (6/2001) there are 31 States that issue driver licenses to select low vision individuals who use BiOptic telescopic lens systems. Collectively there are over 4,000 such drivers in the United States. Despite the fact that such licensing practices have existed in many of these States for 10 - 30 years, some individuals still question, and perhaps rightfully so, the validity and use of such devices for driving. The intent of my presentation is to educate and provide insight as to what driving with BiOptic telescopic lens systems is all about starting with:
1) What is a BiOptic telescopic lens system?
A BiOptic telescopic lens system (abbreviated BTLS) is a combination two(2) lens optical system consisting of a standard or conventional pair of carrier lenses (slide 1); and a miniature telescopic lens unit(s) mounted permanently at a 10 degree angle to the upper or superior portion of the carrier lens (slide 2).
These devices (slide 3), which are mounted in a sturdy frame presenting spring loaded hinges and adjustable nose pads, are prescription in nature and available through an optometrist or ophthalmologist who specializes in clinical low vision.
2) What benefits can a visually impaired driver derive from the use of a BTLS?
Once trained in the proper and appropriate use of a BTLS, a visually impaired driver is able to detect and identify detail (slide 4), color (slide 5) and/or movement of distantly positioned objects or forms more effectively and confidently.
When using the latter device, the visually impaired driver is able to increase his/her " margin of safety " from critical objects or forms present within, along side of , or approaching their intended path of travel (slide 6).
Margin of safety is defined as the time or distance needed by the BTLS user to process, predict and decide whether or not to react to such critical objects or conditions.
Driver education professionals define critical objects or conditions as any object or condition which can be predicted to influence or require drivers to adjust their vehicle's speed and/or lane position.. Examples include: roadway characteristics, other road users and traffic control devices.
3) In what manner, under what conditions and how often would a visually impaired driver use their BTLS during the driving task?
Persons using a BTLS look through the lower carrier lens (slide 7) for general viewing purposes (for instance, for gross object awareness or orientation to their driving environment); and through the telescopic lens unit for more distant detail/color/activity recognition as previously indicated during the driving task (slide 8).
Movement into and out of the telescopic or magnifying portion of the device is accomplished through a simple synchronized downward-upward head and eye movement.
The upper limit of one's pupil should be parallel or in line with the lower portion of the ocular lens end of the telescopic unit during carrier lens viewing.
This offers the best or optimal viewing through the carrier lens and minimal fixation time , going from unmagnified to magnified viewing and back.
Vertical spotting through one's BTLS is recommended only on straight or relatively straight stretches of roadway; and then only in the absence of critical objects or forms within the space cushion surrounding the BTLS user's vehicle. The telescopic portion of this lens system is used for extremely short periods of time (one second or less per fixation ).
Because of its physical location on the carrier lens (above one's normal line of sight or viewing) the telescopic portion of the device will not obstruct the other 95-97 per cent of normal non- magnified viewing accomplished through the larger carrier lens while driving.
The frequency of use of the BTLS is dependent upon the user's ever-changing driving environment , his/her familiarity to the latter, the dynamics of driving environment (slide 9), and an individual's functional vision abilities related to awareness acuity* v. identification acuity* v. preferred viewing distance* (with and without the BTLS).
If the above-mentioned functional visual acuity terms are new to your vocabulary, permit me to define what each means briefly:
*Awareness acuity - refers to the furthest distance at which the presence of any form is first detected (for ex. shapes against the sky, blobs or blurs of color indistinguishable as specific objects);
*Identification acuity - refers the furthest possible distance at which a detected form is first correctly identified (for ex. that red blob is beginning to look like a car);
*Preferred viewing distance - refers to the most comfortable distance for identifying a detected form (for ex. " I am definitely sure now that object is a car ")
Definitions taken from Foundations of Orientation and Mobility, Weiner and Blasch, Eds.,1996 from chapter entitled Low Vision Mobility by Duane K Geruschat and Audrey J. Smith.
4) How do you go about introducing a visually impaired person to the proper and appropriate use of the BTLS for driving?
An easy and effective way to familiarize a visually impaired person to the proper and appropriate use of the BTLS for driving is as follows:
By lesson's end , many of our past students have stated that for one of the first times in their lives, they finally have some concrete idea of how they compare or match up to a normally sighted person in terms of what objects, forms or activity they can detect and identify under magnified v. unmagnified conditions, at different distances, natural lighting and weather conditions.
Students also find themselves capable of using their respective BTLS as an of effective vertical spotting device (needing only .5 of a second per fixation) after only 1-2 hours training.
The latter then sets the stage for continued BTLS reinforcement under dynamic on-road conditions; first as a passenger-in-car, then while driving.
5) What are some of the major misconceptions about driving with a BTLS?
Misconception #1: A BTLS is the " cure all " to being a safe low vision driver.
Misconception #2: Low vision drivers need not use a BTLS in familiar driving environments (slide 17).
Misconception #3: BTLS are used continuously v. intermittently during driving; and as a result, a BTLS user drives blind to traffic (slide 18).
Misconception #4: Approach magnification, or moving closer to an object to see it, is safer than using a BTLS because the field of vision and depth perception are not affected and there is no need to change fixation (slide 19).
Misconception #5: The only way we can determine the safety of BTLS drivers is over prolonged periods of time and field experience.
Misconception #6: Legally-blind BTLS drivers have higher at-fault accident and violation rates than BTLS drivers with milder forms of central visual acuity loss.
6) What type of visually impaired driver would likely make a good candidate for driving with a BTLS?
From my personal experiences of working directly with individuals who participated in our WV Low Vision Driving Study, 1985-1995, and from other authors (including but not limited to: William Feinbloom, OD, Dennis Kelleher, Ed.D., Ian Bailey, OD, and Randy Jose, OD), I would say the following characteristics best describe the type of individual who would be an appropriate candidate for driving with a BTLS (slide 20):
7) What are some of the most common types, styles and power of BTLS used in driving?
The BiOptic telescopic lens systems used in the WV Low Vision Driving Study, were designed and manufactured by Designs for Vision, Inc. (DVI), Ronkonkoma, NY and Edward's Optical Corporation (BITA), Virginia Beach, VA. (slides 26-30)
The range of magnification allowed for use by participants was 2.2X - 4.0X.. In most instances, the strength (expressed in X- powers of magnification) of the BTLS prescribed for our graduates was obtained by dividing the carrier lens acuity level by 20/40, the arbitrarily set visual acuity protocol for our study. 20/40 was the visual acuity screening standard in place in WV for an unrestricted driver's license at the onset of our study.
· 7 individuals were fitted with the DVI 2.2X BIO II (4 OD, 3 OS)
· 2 individuals were fitted with the DVI 2.2 X BIO II Eagle Eye (1OS, 1 OU)
· 6 individuals were fitted with the DVI 3.0 X BIO I (3 OD, 2 OS, 1OU)
· 5 individuals were fitted with the 3.0 X BITA (3 OD, 2 OS)
· 10 individuals were fitted with the 4.0 X DVI BIO I (8 OD, 1OS, 1OU)
· 2 individuals were fitted with the DVI 4.0X EFP (1OD, 1OS)
Other prescription BTLS that have been fitted and dispensed to visually impaired drivers of other States include:
· Ocutech Inc.'s 3X-4X Visual Enhancing System (VES-K) and 3X VES- MINI (slides 31-33);
· Optical Designs, Inc. 4X Behind-The-Lens Telescope (slide 34);
· M-Tech Optics Corporation 4X M-Lens SYSTEM (slide 35).
Of the 32 individuals who completed our program of instruction satisfactorily, 28 graduates were fitted and dispensed BTLS presenting monocular mounted telescopic lens units; while the 4 other remaining graduates were fitted and dispensed BTLS presenting binocular mounted telescopic lens units.
8) What can be done to improve and better regulate driving with a BTLS?
9) Concluding Remarks
In conclusion, learning how to use a BTLS properly and appropriately is just one aspect of formalized low vision driver education training and assessment. (please see LOW VISION DRIVER EDUCATION TRAINING, a published article by Charles P. Huss).
As student learns and gains experience with all the physical, mental and social skills required of the driving task, instruction moves from a spoon-fed approach to that requiring independent decision making.
The latter then permits the introduction of a standardized objective type of on-road driving assessment, including the correct use of one's BTLS under real-world driving conditions.
Such standardized on-road assessments can and have been used to monitor a student's progress and advise instructors and student what areas of instruction need to be emphasized during the remaining weeks of training, prior to consideration of application for driver licensure.
Once again, thank you for this opportunity !!! With time remaining, I will address any questions or concerns that faculty or attendees may have concerning " Driving with BiOptic telescopic lens systems".
10) Questions or Concerns and Responses
Question: I realize that it may differ from individual to individual, but can you give us a basic idea of how much training an individual should have in order to drive with BiOptics?
Answer: In West Virginia, we offered an individualized, competency based, concurrent type of low vision driver training program extending over 6-8 weeks. Normally a student would receive: 30 hours of classroom instruction, 40 hours of passenger-in-car experiences (a combination of environmental awareness and hazard perception skill training, with their prescription BiOptic telescopic lens system in place), and up to 50 hours of behind -the-wheel training if needed.
Concern: (Phillip Hessburg, M.D.) I wanted this paper delivered because I'm not sure I believe this or don't believe this. I think what it proves is that most people do most of their driving at about 20/200 or are able to. I'm not sure that what we're doing with this use of the BiOptic) isn't primarily reading street signs and determining whether a traffic signal is red or green.
I am also not certain whether or not, as ophthalmologists, we should be recommending that we refer visually impaired persons to Doctor Mogk, M.D., Ophthalmologist for evaluation, fitting and prescription of BiOptic telescopic lens systems? Until I know that I am not doing a disservice to such low vision patients, I'm am not going to recommend it. So maybe over the course of the next two days, you're going to convince me that I am not doing a disservice to people. My purpose is to increase the mobility and the independence of elderly people, but I'm not positive yet, nor have you convinced me, that the way to do it is with BiOptic telescopic lens systems. [For more information about fitting a BiOptic, please click here].
Dr. Lylas Mogk, do you want to comment? Are you prescribing them, or should we be?
Response and Question ( by Lylas Mogk, M.D.): No. I have a question, rather than a statement. You mentioned that vision should be stable. What does that mean? Are we talking six months, one year, two years?
Answer: Preferably, congenital in nature, present since birth. Because as the person grows and matures, he or she becomes accustomed to their low vision condition and their perception of the world through those functional parameters. The person's success in many instances is conditional or resultant to past parental upbringing, where for instance parents may or may not of permitted their son or daughter to participate in sports, bicycling, or pedestrian travel independently away from their home surroundings.
What we found in the WV Low Vision Driving Study, 1985-1995, is that though 107 individuals were identified as meeting the arbitrarily set visual protocol for inclusion in our study, not all wanted to participate. In fact, as a result of further screening procedures and participation in intensive driver education training ( 2 hours of classroom, 2 hours of passenger-in-car, 2 hours of behind-the wheel training, and normally at least an additional 2 hours of self-study per day, for 6-8 weeks) only about 30 per cent of our population sample were able satisfy the requirements for completion of our program and considered driver ready for application for WV driver licensure.
Statement by Dr. Mogk: That's what I thought you meant. There is a lot of confusion about that term in the senior population and the people who care for them, because often people are described as having stable macular degeneration.
Response: One of the things I think we should all remember is that persons who develop age-related dry macular degeneration oftentimes had normal visual acuity and fields of vision in their growing years, along with a 20/20 brain. As they age and develop macular degeneration (along with the reduction in visual acuity functioning, say 20/200 in their better functioning eye), they are still trying to interpret the world around them with a 20/20 brain. And that is where as a driver evaluator or driver educator you will notice or observe such individuals illustrating orientation related difficulties, because of their desire to still remain orientated to their surroundings with their former 20/20 brain.
Concern (from Dr. Mogk): That I certainly understand. The further concern is, as soon as they are fitted and trained, their scotoma changes.
Response: Remember, the BiOptic training exercise that I shared with you is only a small fraction of the extensive passenger-in-car training which respective candidates participate in as part of their formalized program of low vision driver education training and assessment. The enclose newsletter article will give a better awareness of the various stages of screening, training and assessment included in our respective program of instruction. In fact, the WV Code allows us to screen, train and assess potential drivers without a valid WV instructional permit, as long as such instruction is provided by a driver educator licensed by the State and conducted in a dual brake controlled vehicle. The latter allows us to adequately determine which candidates are v. are not driver ready for continuance with driver education training and subsequently application for driver licensure. And sometimes it takes 3-4 weeks to determine the latter.
Concern (Dr. Barry Skarf, M.D.): I'm a neuro-ophthalmologist. I wanted to point out also regarding the question of Dr. Mogk. The younger the person - it does not have to be in my experience - a congenital defect; though people with congenital defects amaze me at the ability they have just learned because their brain has worked with what they have been born with.
But even young people, as teenagers, or I have a young fellow who was 10 years old when he lost part of his vision - or even in their thirties or forties - they're motivated, and they are willing to make an effort, and they got a stable condition. For instance, a young person who lost bilateral vision due to optic atrophy, let's say hereditary optic atrophy, it's a condition where you you lose central vision, but once you lose it, it's stable, and those people are often 20/200. Those people, if they're motivated, can learn to function better, but I think that the older a person gets, motivation isn't related to age , and learning isn't related to age, but there is a co-relation. It becomes a problem. Unfortunately, that age population is the one that has the big numbers.
Response: I agree with you Dr. Skarf. I would also like to point out that it has been our experience in West Virginia, that environmental awareness training or re-training with prospective low vision drivers, regardless of age or onset of their respective visual impairment, is facilitated if we break down the various groups of critical objects or conditions into subgroups and have students learn or re-learn to detect and identify such objects or conditions one subgroup at a time. For example, with the student positioned as a passenger in the front right seat of the driver education vehicle, have them practice detecting and identifying verbally the larger and more noticeable roadway characteristics such as a dip in the road, curve in the road, hill ahead, fixed hazards in or along side of the roadway which restrict or interfere with other road users' line of sight to them and their line of sight to other road users.
Then practice detecting other road users, whether they be on two feet or four feet, two wheels or several wheels.
Then, integrating the proper and appropriate use of their prescription BiOptic lens system; having the student practice detecting detail or signage off of distantly positioned road signs, color off of traffic lights, or other forms of activity or other gross movement in their magnified field(s) of view which may need to be responded to in terms of speed and or lane position adjustment of their vehicle when driving.
In other words starting with the big picture of their driving environment, and then locating more specific detail within that ever changing dynamic setting.
Concern (by Dr. Hessburg): I think that one of the things that distinguishes the West Virginia program from others that we've seen is that your program is more intensive. I know that in some States, and I have anecdotal evidence in our own State, that people use their dispensed BiOptic lens system to take the test and never drive with them on. They use the BiOptic lens system to pass the test (20/40 letters or numbers of an acuity chart) because of the magnification of the latter device But the latter device is not being used during driving. Whether they are not being trained properly, or whether our State does not require them to be trained, I do not know. But when I see them in my office, and I ask them, " how much of the time do you drive using the device?" They say " well, I always have it in the car with me ".
Response: It has been our experience that if lack of use of the device does occur, it is more likely to take place with individuals presenting more mild levels of visual acuity loss (say in the range of 20/50-20/70); and less likely to be abused or non used by individuals with more moderate levels of visual acuity loss (say in the 20/80 - 20/120 range or 20/140 -20/200 range).
Like any device, if someone is taught how to properly utilize the device, especially as it presents itself here under dynamic conditions (and the benefits of its usage is made known or experienced by the user, under real world driving conditions, the likelihood of use is enhanced several-fold.
On a separate note and related to your statement Dr. Hessburg, the visual screening in West Virginia, is usually waived and replaced by results of a complete eye examination , provided by a licensed ophthalmologist or optometrist of a student's choice, on a form called a Driver License Advisory Board Vision Report Form (DLAB-2 Form), which is then sent to our DMV headquarters in Charleston, WV, reviewed by our State's DMV Medical Advisory Board; and then recommendation is made to the DMV Commissioner as to whether or not to issue or deny an instructional permit for driving.
Concern (by Kathleen Miller, OTR/L): I am an Occupational Therapist, employed by Edwin Shaw Hospital, Akron, OH. I do training with low vision clients. I initially started as an occupational therapist doing driver evaluations for people with disabilities, such as strokes, head injuries, amputations, various problems. I was approached by an optometrist in Ohio to do the training aspect of it in the Akron area. The Columbus area also has a program, and they have been established for approximately nine to ten years.
So they have a pretty established program, but typically, the clients need to go to an established clinician that deals with these programs, and they need to be prescribed telescopes through these experienced professionals.
Then they need to have a mobility specialist who takes them out to make sure that they know how to use them as intended.
Then in turn they come to professionals like myself and we do the on-road training, including the correct integration and utilization of their prescription BiOptic lens system during the driving task.. If they are able to complete all of the above types of training and requirements, then and only then are they permitted to apply for driver licensure in the State of Ohio. The State of Ohio has specifically trained officers or driver license examiners that test prospective low vision applicants for driver licensure. Perhaps the lack of formalized programs of low vision driver education training and assessment in other respective States, that also license BiOptic driver applicants, is one main reason why some such drivers under-utilize or never realize the true benefits derived from their use under dynamic real world driving conditions.
Response: Thank you for bringing the latter to the attention of attendees of this colloquium. I am very familiar with the formalized programs of low vision driver education training and testing in States such as Ohio, Indiana, Virginia, Maryland and most recently Kentucky where fellow staff and I from the WV Rehabilitation Center have been directly involved in staff training issues (including DMV or DPS driver examiners and supervisory personnel), legislative efforts, and program development in years past.
Those interested in more information can also write or call:
Charles P. Huss, C.O.M.S. Coordinator, Low Vision Driver Services
West Virginia Rehabilitation Center P.O. Box 1004 Barron Drive Institute, WV 25112 TEL: 304-766-4803 FAX: 304-766-4816 Charles P. Huss is an Academy Certified Orientation and Mobility Specialist with 25 years of teaching experience with visually impaired individuals (K-Geriatrics).
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