Low Vision Aids
by Heather Mason
Low vision devices for near and intermediate tasks
|Short working distances||Useful for
reading provided there is adequate magnification for the task.
|Inexpensive, cosmetically acceptable. Provides from 1.5x to 8x magnification.||Short, sometimes very short working distances.|
|Hand magnifiers||For short inspections such as looking at a price tag or an index. As a supplement when necessary for reading smaller print than can be seen with devices used for general reading.||Available in magnifications from 1.5x to lOx. Portable, relatively inexpensive.||Require the use of one hand and no significant hand tremor.|
|Stand magnifiers||Useful for general reading and in the classroom.||Available in magnifications from 1.5x to 15x. Some models may be mounted in spectacle frames.||Best performance only with short working distance, as little as a few centimetres in higher powers. Higher magnifications usually require use of the short working distance.|
|Illuminated hand and stand magnifiers||Useful where performance at near improves with increased illumination. Highest powered optical magnifiers, up to 15x. Useful when away from usual light sources.||Features will be the same as the equivalent hand or stand magnifier. Illumination provided by disposable or rechargable batteries, or by mains operated handles in some models.||Limitations will be the same as the equivalent hand or stand magnifier. Will require a replacement of disposable batteries, changing and recharging of rechargable batteries or mains power.|
|Head-borne magnifiers||For tasks which require use of both hands and where working distance is not critical.||Leave both hands free. Usually mounted on a head band or spectacle frame.||Limited range of magnification. Often cosmetically poor|
|Near point telescopes||For tasks which require the use of both hands and which cannot be done at very short working distances.||Consist of either a distance telescope with a near attatchment or a telescope designed to be used for near tasks only. Mounted in spectacle frame. Longer working distance than other forms or near low vision aids giving the same magnification.||Cosmetically poor. Limited field of view, as magnification and working distance are achieved at expense of field of view.|
|Electronic magnifiers||Where performance with optical magnifiers is not sufficient for needs, because of magnification required or the volume of near work required.||Available in higher powers up to 50x magnification and with better field of view than optical magnifiers.||
Most models are not portable.