DOUBLE-MASKED PLACEBO-CONTROLLED TRIAL OF PRECISION SPECTRAL FILTERS IN CHILDREN WHO USE COLORED OVERLAYS

We selected 68 children who reported benefit from individually chosen sheets of coloured plastic placed upon the page when reading, and who used these regularly without prompting. These children viewed text ill uminated by coloured light in an apparatus that allowed the separate m anipulation of hue (colour) and saturation (depth of colour), at const ant luminance. Many of the children reported improvements in perceptio n when the light had a chromaticity within a limited range, which was different for each individual. A pair of plastic spectacle lenses ('ex perimental' lenses) was dyed so as to provide the appropriate chromati city under conventional white (F3) fluorescent light. An additional pa ir was prepared having very similar colour but with a chromaticity out side the range in which perception was reported to improve ('control' lenses). Each pair was provided for 1 month in random order. The child ren kept diaries (36 completed) recording symptoms of eye-strain and h eadache. The children and those responsible for their assessment were unable reliably to distinguish 'experimental' from 'control' lenses. N evertheless, symptoms were less frequent on days when the 'experimenta l' lenses were worn (P < 0.003).