Non Optical Devices

There are many ways in which poorly sighted people may gain extra independence in their every day lives. Eccentric viewing and Lighting play important roles in enabling the individual to achieve particular tasks. However there are two groups of devices that are specifically tailored to the needs of the visually impaired.

Optical Devices provide assistance through the use of some form of optical lens system either a single lens system, e.g. a magnifier, or alternatively multiple lens system, e.g. telescopes or monoculars. The other principal categories of devices that are available are the non-optical devices.

Non-optical devices are aids that have usually been developed for use by the visually impaired to accomplish a specific task, without the use of any form of optical image enhancement. Probably the most easily recognised aid would be the awareness cane, or white stick as it used to be known.

This device is designed primarily to make well-sighted people aware that a visually impaired person may have some difficulty with some tasks, such as crossing a road, and to make allowances. Another similar device is the partially sighted badge that again allows a person to declare their lower visual function. However some care should be exercised with this type of device since it has not been unknown for unscrupulous individuals to target poorly sighted people for criminal ends.

Other devices that can be obtained include coin holders, talking clocks and watches, stick on raised pads for dials, large print telephone dials, writing frames and typographs. The latter is basically a matt black card into which a rectangular hole is cut to allow writing through. They are available commercially for writing and also tailored to specific needs such as cheque writing.

The other main category of non-optical device is the CCTV (Closed Circuit Television) system.The basic principal behind these types of unit involves a small camera being used to ‘view’ the reading matter. The image generated is then converted into a television signal that can be projected onto either a television screen or dedicated monitor. The sophistication of this type of device ranges from a basic monochrome camera mounted within a small handheld ‘mouse’ that is run over text manually through to full colour systems featuring high quality stand mounted cameras, moveable reading tables and true colour monitors.

The principal advantage of these systems is the virtually unlimited magnification possible with little or no image distortion. Maximum magnifications can be as high as 30x although the actual benefit of this high degree of magnification may be limited through the quality of the print. Another advantage demonstrated with these units is the ability to reverse colours so that in place of black text on a bright white background you could switch to black background with white text.

The main drawback for most of these units is their lack of portability, although some systems claim to be portable. A recent advance in the field of electronic devices are distance viewing units in which a CCD miniature digital camera system is mounted on a head band frame. A magnified image is then projected onto small LCD screens within the head-mounted device. As with the CCTV units, digital technology allows for high levels of distance magnification although the devices are used solely for personal use.

An extension of this type of device is the talking book. Access to the vast libraries of talking book cassettes has become easier of late and the quality of production is such that many normally sighted people gain pleasure from listening to them as well.

There are a vast number of other everyday devices that may be adapted and employed for use by the visually impaired. Combining these with the commercially available, task specific devices will enable the visually impaired individual to retain a large degree of independence, limited only by their imagination.