Illumination

The role of lighting in assisting those with poor vision is probably the single most important, and conversely neglected, factor of low vision care. Many conditions resulting in reduced visual acuity cause a marked increase in sensitivity to glare but a need for increased task lighting. Consequently any extra illumination must be directional rather than just a general increase in ambient light levels. Additional lighting may take one of many various forms. Usually the illumination is stand mounted although wall and hand mounted units can also be considered. A good level of non-glare directional illumination can give as much benefit as a 2x magnifier.

Lighting sources can utilise a number of bulb types, each with claimed benefits, but ultimately the actual usefulness of a particular unit is dependent on the individual user.

Standard Bulbs
These are relatively inexpensive and easy to obtain. When used in a directional unit such as an anglepoise lamp, a 60 watt bulb is usually sufficient. Principal drawbacks of this type of bulb are the ‘yellow light’ they produce and the amount of heat they generate.

Daylight Bulbs
These bulbs are similar to standard bulbs but have a filter coating which produces a light of similar colour temperature to daylight. As with normal bulbs a 60 watt unit should be more than sufficient.

Halogen Bulbs
Utilising differing gases within the bulb to produce light, halegon bulbs produce a very bright, white light that is particularly effective for near vision tasks. Whilst the actual bulb does get quite warm, halogen units tend to be cooler in use than an equivalent standard bulb. Principal drawbacks with halogen bulbs tend to be the relatively narrow beam of light they produce.

Fluorescent Bulbs
By using phosphorescent coatings inside the tube, fluorescent lights can produce light of varying colour temperatures, ranging from a warm yellow sodium colour through to the cooler blue-white daylight equivalent.

Fluorescent tubes produce a very even illumination and have the advantage of offering a good spread of light making them ideal for general reading tasks. Due to the nature of the light produced, fluorescent units tend to be quite cool allowing for the lamp to be placed quite close to the user.

LED
Light emitting diodes offer some significant benefits over the many other light sources principally connected to their low power consumption and relatively long life. LEDs are currently used in illuminated magnifiers but, because of their relative low light output, are not recommended for external lighting tasks.

Artificial lighting can never replace daylight for intensity or effectiveness but if used correctly can offer significant benefits to the user. To obtain maximum effectiveness the lighting should be positioned behind and slightly to one side of the shoulder so that light can fall unimpeded on the reading matter. Any additional magnification can then be positioned so as to avoid distracting reflections.

There are many suppliers of suitable units including high street retail chains, various catalogue shops and DIY stores. Many units are also now relatively inexpensive. There should really not be any reason for failing to optimise the level of illumination.