This paper does not address all possible forms of lighting for the elderly. Rather, it seeks to explain what it is about the elderly visual system that makes changes from conventional lighting practice desirable and then to summarise what those changes are. As the visual system ages, the range of distances over which focus can be achieved is diminished, the amount of light reaching the retina is reduced, more of the light entering the eye is scattered, and the colour of the light is altered by preferential absorption of short wavelengths. Everyone who lives long enough will experience these changes, but with increasing age there is also an increased probability of pathological change in the eye. These pathological changes can lead to partial sight and, ultimately, blindness. The consequences of all these changes in the visual system with age are reduced visual acuity, reduced contrast sensitivity, reduced colour discrimination, increased time taken to adapt to large and sudden changes in luminance and increased sensitivity to glare. Lighting can be used to compensate for these changes, to some extent, and hence can be used to support the independence and quality of life of the elderly.
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