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Driving with Low Vision
Bioptic telescopes, just like binoculars, enlarge images, though their value to the visually impaired for driving is not to see things larger, but to see them further away. The difficulty that the visually impaired encounter while driving is that they must get so close to a sign or signal to see it, that there is not sufficient time for them to make the appropriate driving adjustments. The bioptic telescope allows them to see the target further away, giving them more time to react. In practice, the telescope will increase the individual’s ability to see 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 when they would only be able to see it at 20 feet with their normal vision— a 4 times performance gain.
How are bioptics used in driving?
While driving, bioptics are used in much the same way that we use side and rear view mirrors— for spotting purposes and for brief periods of time. 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 to be 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 mirrors is also experienced when learning to use bioptic telescopes.
Field of View:
Bioptic telescopes are available as either small Galilean designs which offer narrow fields of view—about 5 degrees at 3x power, and Keplerian telescopes, which offer significantly wider fields of
The most frequent complaints users express regarding bioptic telescopes are their narrow fields of view. Ocutech's success has been in designing improved bioptic telescopes that address the issues of field of view in a design that is lightweight, comfortable, and less conspicuous. In particular, the Ocutech VES-Mini, a 3x Keplerian telescope, offers a combination of the smallest and widest field of view of any device available today-in fact its field of view is almost three times larger than most other traditional bioptics. It is particularly well suited for bioptic driving applications.
The Ring Scotoma:
When looking through a bioptic telescope the enlarged image obscures some of the normal field of view. This is called the “Ring Scotoma.” Because some visual information is not seen while sighting through the bioptic telescope, there is concern that the driver might miss obstacles while they are using it. 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 amount when they adjust the radio, the heater or air conditioner, or use their side or rear-view mirrors. As a result, the ring scotoma is of no greater concern than many other normal driver activities.
Telescopes 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. Beyond 20 feet bioptic telescopes are at “optical infinity,” meaning that everything will be 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.
For more information contact:
109 Conner Dr. #2105
Chapel Hill, NC 27514 USA
Ph: 800-326-6460 / 919-967-6460
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