A double-masked randomized controlled study with cross-over design compared the effectiveness of precision ophthalmic tints in the prevention of headache in migraine sufferers. Seventeen patients chose the colour of light that optimally reduced perceptual distortion of text and maximized clarity and comfort. They were later given glasses with spectral filters providing optimal colour under conventional white lighting ('optimal' tint) or glasses that provided a slightly different colour ('control' tint). The tints were supplied in random order, each for 6 weeks, separated by an interval of at least 2 weeks with no tints. Headache diaries showed that the frequency of headaches was marginally lower when the 'optimal' tint was worn, compared with the 'control'. The trial extends to adults with migraine, the results of a previous double-masked study demonstrating, in children with reading difficulty, beneficial effects of precision tints in reducing symptom frequency. In the present study, however, the effects are suggestive rather than conclusive.