Visual disability and home lighting.

13 men and 43 women (average age 76) attending a low-vision clinic with visual acuity of 6/18 (Snellen) or less had acuity measurements made under standard (measured) hospital conditions, under normal home conditions, and under home conditions with augmented lighting. Median levels of ambient lighting in the home were 1/10 of those in hospital, while levels for reading were 1/7. Augmented lighting at home (a 60 watt bulb in a small adjustable lamp) improved visual acuity in 82% of subjects, restoring all but 11% to the levels achieved in hospital or above. Improvement was unrelated to disease. General levels of lighting are often so poor in the homes of elderly people that the number of people functioning as "blind" is twice what it need be. Simple improvements to lighting would reduce the prevalence of "visual disability" (less than 6/18 Snellen) from 520/100,000 home-based adults to about 300.