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Bioptic Low Vision Aids for the Visually Impaired

Driving with Bioptic Telescopes

  Learning to Use Your Bioptic Telescope Reading with Bioptic Telescopes 

Henry A. Greene, O.D., F.A.A.O.
Clinical Professor Department of Ophthalmology
University of North Carolina at Chapel Hill

Bioptic telescopes can help the visually impaired to be safer drivers, thus increasing their independence and enhancing their quality of life.

Normal highway sign view

Highway sign to normal viewer.


Simulated 5-degree field of view with 3x Galilean bioptic

Simulated 5-degree field of
view with 3x Galilean bioptic.

Simulated 12-degree field of view with 3x Keplerian Bioptic

Simulated 12-degree field of
view with 3x Keplerian Bioptic.

What are bioptics and how do they help driving?

Bioptic telescopes, are eyeglasses that contain miniature telescopes mounted toward the top of the eyeglass lens. They function in much the same way as binoculars by enlarging images, though their value to the visually impaired for driving is not to see things larger, but to see them further away. While binoculars might be used continuously, drivers using bioptics look through their regular eyeglass lenses most of the time, and only sight through the telescope for short periods of time.

VES-Mini Bioptic Telescope

The challenge that the visually impaired encounter while driving is that they must get so close to a sign or signal in order to see it that there is insufficient time for them to make the appropriate driving adjustments. The bioptic telescope allows them to see the target sooner, giving the driver more time to react. In practice, the telescope increases the individual's ability to see further away by a factor of the power of the device. For example, a 4x telescope will allow the user to see a sign at 80 feet through their bioptic, while they would only be able to see it at 20 feet with their normal vision- a 4 times distance gain.

Bioptic Telescope Field of View

Bioptic telescopes are available as either small, Galilean optical designs which provide narrow fields of view-about 5 degrees at 3x power, and Keplerian telescopes, which offer significantly wider fields of view-usually about 12 degrees but as much as 15 degrees.

Learning to use bioptics for driving

While driving, bioptics are used for spotting purposes and for brief periods of time -- in much the same way that we use side and rear view mirrors. Automobile mirrors are quite small, and in fact provide narrow fields of view themselves, quite comparable, in fact, to the field of view through a bioptic telescope. When we first learned to drive, most of us found mirrors difficult to use, and we often preferred to turn our heads to make certain that the way was clear. Over time, using mirrors became easy and natural, and ultimately indispensable. The ”learning curve" involved in using bioptic telescopes is much the same as that experienced when using mirrors.

The Ring Scotoma

When looking through a bioptic telescope the enlarged image obscures some of the normal field of view. This area of lost vision is called the "Ring Scotoma." Because some visual information is missing while sighting through the bioptic telescope, there has been concern that the driver might not see a potential obstacle. This would certainly be an issue if the individual were to be looking through the bioptic all of the time, but as we have already discussed, this is not the case. In fact, drivers miss visual information much more frequently and to a greater extent when they adjust the radio, the heater or air conditioner, or use their side or rear-view mirrors. As a result, the ring scotoma concern should not be considered any greater an issue than other normal driving activities.

Focusing

Bioptics can either be fixed focus, manual focus or autofocus. When users are sighting through the bioptic for driving, they will be looking at distances greater than 20 feet away-a distance at which telescopes are at "optical infinity." At optical infinity everything is in focus from 20 feet and beyond without refocusing. As a result, if the sole purpose of a bioptic device is for driving, a fixed or manual focus device (that could have its focus locked in position if necessary) is all that is required. However, bioptic telescopes have applications beyond driving—in stores, classrooms, at work, while traveling, visiting museums, etc., and these activities are often at distances closer than 20 feet- distances where focusing is necessary. As a result, a visually impaired driver might elect to obtain a manual or autofocus device for the other applications for which it can be useful, while not focusing it while driving.

Legal issues about driving with bioptics

Many states in the US and some countries allow visually impaired individuals to use bioptic telescopes to drive. However each Motor Vehicle Agency has its own rules and regulations regarding driving with bioptics. You should consult your low vision specialist and your jurisdiction's Department of Motor Vehicles to determine the requirements for using bioptics for driving in your community. Decisions regarding driving with bioptics rest solely with the licensing agency, the prescriber and the user. Ocutech makes no claims regarding the fitness of any of its devices or the fitness of any individual using bioptic devices for driving.

 

  Learning to Use Your Bioptic Telescope Reading with Bioptic Telescopes 

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