Bioptics and Driving
Over the past 40 years, bioptics have in part allowed thousands of Americans, whose vision falls below the standard legal visual acuity limits (20/40-20/60), to drive an automobile. Persons who benefit from the latter optical devices illustrate visual conditions that reduce resolution or clarity of vision while maintaining peripheral or side vision intact. The latter might include conditions as: albinism, nystagmus, corneal diseases, macular degeneration and others that affect the central macular area of visual functioning; that which is responsible for our detail and color vision abilities.
What is a bioptic?
A bioptic is a combination two-lens optical system with a telescope(s) attached to a pair of glasses, above one’s normal line of sight (see sample bioptic lens system below). These devices are prescription in nature and available through an optometrist or ophthalmologist who practices clinical low vision. These optical low vision aids are available in a number of different styles, sizes and powers. The most common telescopic units used for driving purposes range from 2.0X - 5.5X (“X” referring to the strength or power of magnification of the telescopic lens unit).
The photo in Figure 1 reveals a frontal view of an older yet still widely used Designs For Vision (DVI), Inc. (Ronkonkoma, NY) 2.2X Galilean BIO II bioptic telescopic lens system in a standard black yeoman frame (note the physical location of the telescopic units, which are above the normal viewing area through the carrier or support lenses).
How are bioptics used during the driving task?
Persons using bioptic lens systems look through the larger or standard carrier lenses for general driving purposes 90-95 percent of the total driving time; and dip down into the miniature telescopic lens unit(s) briefly and intermittently using a simple synchronized head and eye vertical drop technique to discern detail, color or activity as illustrated below.
Photo No. 2: A lateral view of a person looking through the carrier lens of a Designs For Vision, Inc. (DVI) 2.2X Galilean BIO II mock-up bioptic telescopic lens system (in new brown titanium frame), Ronkonkoma, NY
Photo No.3: A lateral view of a person looking through the telescopic portion ofa Designs For Vision, Inc. (DVI) 2.2X Galilean BIO II mock-up bioptic telescopic lens system (in new brown titanium frame), Ronkonkoma, NY
What benefits are derived from the use of a bioptic lens system?
Once trained in its proper and appropriate use, a low vision driver using a bioptic lens system is able to detect and identify detail, color, and/or movement of critical objects or forms at more normal distant viewing positions during the driving task.
In driver education circles, critical objects or conditions are often defined as any object or condition that which can be predicted to influence or require drivers to adjust their vehicle’s speed and/or lane position. Examples of the latter include: roadway characteristics, other road users and traffic control devices. As a result bioptic drivers increase their margin of safety from such objects or conditions that are present within, along side of, or approaching their intended path of travel.
How many States recognize the use of bioptics for driving?
Thirty nine (39) States currently allow the use of bioptic lens systems for visual assistance in the driving task. Approximately half of those States now offer some type of formalized low vision driving services, with a minimum of 20-30 hours of behind-the wheel instruction recommended or required for novice driving candidates. Ideally the use of more than one instructor is recommended for this subgroup of potential drivers; for example the use of a certified orientation and mobility specialist (COMS) for determination of pre-driver readiness, basic distance viewing skills including bioptic utilization skills, critical objects awareness skills, and a certified driver rehabilitation specialist (CDRS) for all classroom and behind-the-wheel evaluation and training.
What are some of the common misconceptions about bioptic driving?
A few of the common misconceptions about bioptic driving are as follows:
Misconception: Low vision drivers need bioptic lens systems to “see”.
In reality low vision drivers can “see” at varying distances, but not as distinctly as a person with 20/20 distance visual acuity. Engaging telescopic magnification as needed provides sure acuity or clarity of vision. Likewise, all motor vehicle operators drive with reduced visual acuity using our para central and peripheral fields of view approximately 90-95 per cent of the total driving time.
Misconception: Bioptic drivers view continuously v. intermittently through the telescopic portion of their bioptic lens system making the device unsafe for driving.
In reality, trained users glance briefly in and out of the telescopic portion of their device as the need for enhanced acuity arises. Vertex distance, the linear distance between the center of the cornea or clear front window of the eye and the center of the ocular lens of the telescopic lens unit allows the bioptic user to maintain gross awareness of their constantly changing environment while driving.
Misconception: Low vision drivers need not use bioptics in familiar outdoor environments.
In reality we have no control over anything that takes place outside of one’s vehicle. A high state of alertness is needed by all drivers, including those who are visually challenged.
Misconception: Extensive training with the bioptic is needed if it is to be integrated successfully into the driving task.
In reality, greater emphasis initially with young novice drivers should be placed on the development of effective distance viewing skills (including but not limited to: eye lead time or distance, head and eye scanning and following distance), critical object awareness skills (big to small) and hazard perception skills. What is important to remember is that if a student does not feel comfortable with the big picture of the driving scene, he/she will experience considerable difficulty finding or locating detail within the big picture with or without telescopic magnification.
What resources are available to increase one’s knowledge of driving with bioptics?
Please find listed below references for more information about low vision driving with bioptics:
- BiOptic Driving Network, Inc. (2001) - www.BiOpticDriving.org
- Driving with Confidence: A Practical Guide to Driving with Low Vision (Peli & Peli) book publication (2001), http://www.worldscientific.com/
- Indiana Bioptic Driving video (2002) - 2...@eyeassociates.com
- Driver Rehabilitation and Community Mobility: Practices and Principles, (Editor -Joseph M. Pellerito Jr., MS, OTR/L, Wayne State University) book publication (2005), www.elsevierhealth.com or phone: 1-800-545-2522
- International Academy of Low Vision Specialists (IALVS) – www.ialvs.com/
- UPDATE—Low Vision Driving with Bioptics (2000-on) (Chuck Huss, COMS, Consultant – Bioptic Driving, chuc...@wvdrs.org)
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