Optical Devices
Telescopes
Distance vision telescopes are the only form of optical device that assist a person with low vision with distance tasks, where conventional glasses are unsuccessful. They improve the resolution of objects by enlarging the image, thus bringing the object closer (angular magnification).
The field of view becomes larger the closer the telescope is held to the eye. Therefore, it helps if the user wears the refractive device. However, telescopes are also available as hand-held devices for single eye or monocular use, in powers of 2X, 3x, and 4x magnification.
Telescopes can be used for the following distance vision tasks:
- Specific tasks requiring magnification at variable distances, like reading from the blackboard and recognizing faces at a distance
- Spot-distance viewing, like watching television and sports events, or seeing bus numbers and street signs, so that one can travel unassisted.
Although telescopic devices can be of tremendous help in many different situations, they may not always be immediately accepted or incorporated into the daily routine. They may appear clumsy and unattractive, and may be rejected for cosmetic reasons. Moreover, they reduce the field of view; that is, your view of the distance is much narrower through a telescope although it may be much clearer.
Telescopes can disrupt spatial judgement, as the object appears closer than it is. Low vision telescopes can be most useful if accompanied by a concentrated and careful instructional training programme, which includes localization, fixation, scanning and tracking.
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