Telescopes and binoculars are multi-lens devices that are used primarily for viewing the distance, but can be adapted for use at closer distances. While most of us are familiar with the common celestial telescopes and bird-watching binoculars, the systems for use by those with low vision are miniaturized.
These multi-lens systems are the basic option for those who need magnification for the distance. They have the effect of making things in the distance appear larger and closer.
An important factor to keep in mind with telescopes and binoculars is that stronger is not always better. The stronger the lens system, the heavier and longer in length it becomes. Another factor is field of view. The field of view is the amount of area you are able to see through the system. The more powerful the magnification, the smaller the field of view.
This optical aid is used over one eye.
There are several types:
Hand-held telescopes are very portable and inexpensive. These units are used intermittently for spotting distance objects.
Mounted on eye glasses, these telescopes are better for long term viewing, but not for walking around. These are best used in a sitting position for viewing sporting events, theater, and watching television. They are more custom, and need to be prescribed, measured, and aligned by a qualified professional.
Clip-on style of telescopes tend to be another option similar to the hand-held telescope with a clip attached to it. These are best used in a stationary position.
Within these categories there are those that are focus-able and those that are fixed focus.
Fixed focus means that the distance is not adjustable. What you see is what you get.
Focus-able offers more flexibility. While some are limited to focusing at different distances, others are able to focus at the intermediate, which is within 10 feet, or near, which is within 16 inches.
Telemicroscopes are multi-lens systems used for the near reading distance. They can be telescopes or binoculars. They can be the previously mentioned focus-able type or they can be in the form of a reading cap, which is placed over the end of the telescope to turn a distance viewing system into one which can be used to read at near. The benefit of this near reading option over high powered reading glasses is the capability to hold the reading material at a further distance rather than the very close reading distance required by high powered reading glasses. The disadvantage is the smaller field of view.
Binoculars can be hand-held or made as a set of head mounted spectacles. Both of which should be focus-able. The head-mounted style can be found as a relatively inexpensive option, that you can adjust the fit and alignment yourself. They tend to be heavy and awkward looking.
There are also custom made head-borne binoculars in which the lenses are mounted through the lenses of a standard- looking set of frame and lenses. Considerably more expensive, but well-worth it if needed for long-term viewing.
Bioptic is a term used to describe where the telescope is mounted on the eyeglass frame.
Whereas the previously described telescopes and binoculars were centrally located, these bioptics are located above the line of sight. Because the placement of the lens system is above the line of sight, a person can walk around with the spectacle mounted device. when needed, the user, drops their chin slightly, and because the telescope has a slight 10° upward turn, the lens is now positioned perfectly in front of the eye to spot distance targets.
Bioptics are the type of telescopic system used by those qualifies as low vision drivers. The bioptic is mounted over one eye, and is used intermittently by the driver to spot distance signs and traffic patterns.