An assistive device can be as simple as a black felt tipped pen or as complicated as a voice recognition computer programme that writes a letter for you. Some are optical, that is, use lenses and prisms, which we have used for hundreds of years while others use the latest computer technology to enhance print or convert it into audio text.
In many cases common sense and imagination will be useful:
- Illumination – spotlight work areas, use brighter globes
- Contrast – use coloured coasters or back grounds
- Size – use larger and bolder text
- Tactile – use nail polish or hard setting putty to mark dials and devices
While some service providers offer a total and comprehensive service in other cases more than one provider will need to be seen. It is important to realize that no one assistive device can replace our complex vision- to see objects in the distance as well as those up close, to see colours and in the dark, to detect depth, contrast and movement. Too many low vision patients expect a “one device fits all” solution while others buy too many devices and master none.
For an assistive device to be successful 3 important steps need to be followed:
- Accurate assessment
- Good choice of device
- Training in use of the device
These are provided by a low vision therapist after careful assessment of your remaining vision. The 3 techniques he will use will incorporate size magnification, distance magnification or angular magnification.
Magnification devices can be spectacle mounted, hand held or free standing. Some magnifiers have a built-in light source while others have long flexible “goose necks”. An important point to remember is that the higher the magnification the shorter the viewing distance. Telescopic devices are useful for distance viewing and in some countries low vision patients with Bioptic devices are even allowed limited drivers licences.
Reading machines can be stand alone or linked to computers. A Closed Circuit Television Reader is a stand alone instrument with a movable bed that magnifies text onto a TV type screen. Magnification and contrast are both variable and this is an excellent but expensive reading device. The latest models can also be linked to the computer for more versatility.
Small hand held readers with a built in screen and variable magnification are portable and thus very useful for a variety of tasks. The choice is endless and to ensure that you are prescribed the correct device visit a reputable service provider with a list of 3 or 4 of the most important visual tasks you need help with.
Ultraviolet light may increase the rate of degeneration in retinal conditions and good UVa , UVb and blue light screening lenses offer not only protection but a decrease in glare sensitivity. These properties can be incorporated into your prescription lenses but the new, less expensive poly carbonate plastic lenses also offer excellent protection. Ask advice from your Optometrist or Low vision therapist.
The rapid advancement of application and miniaturisation of new technology has helped in the production of computer based programmes and devices for low vision patients. The range is vast and a visit to a specialized service provider is critical. To help understand what you should look at here are some general descriptions.
Screen Magnification and voice software
These programmes will convert normal text into an accessible format – either to a magnified version or a voice based version. Some programmes do both and people with progressive vision loss should consider a dual package. This software is expensive and a free trial version of the programme should be requested.
The newer versions of Windows have both elements built-in, look for the accessibility icon on your control panel. Desk top icons can be magnified and email text magnified or converted to voice. Contrast and size are both variable as is curser size and trail, but key stroke substitution for most mouse tasks will save hours of curser hunting. Adequate training will result in far better utilization of the programmes.
Text scanners bring text to the computer so that the above programmes can make the text available to the low vision patient. The new MOUSE type scanners are portable and when coupled with a lap top with screen reading or magnification software will sometimes be all that a low vision patient needs in the work place. A fixed scanner at a work station could be available via a computer network to other workers and might be a more cost effective solution for employers.
A stand alone Optical Character Recognition scanner converts text to speech. These are expensive but versatile machines for those without computer skills. Text can be saved and deleted.
Other Devices & Services
Voice to text programmes
Voice to text programmes need some training to recognize your voice but are of enormous benefit to people with poor key board skills. Speech programmes for Mobile phones are extremely helpful for text or phone book access.
Non Governmental Organisations provide this service in most countries. A student service will also convert text books onto tape or CD, check with your local Retina group for service providers.
Free Telephone Directory Assistance
Some telephone service providers have a free telephone directory enquiry service for visually impaired users. Check with your local provider.
Skills of Daily Living Instruction
As a part of mobility training, some organisations provide a Skills of Daily Living (SDL) instructor who will offer useful tips, training and coping techniques for the home or work place.