The Intuitive Overlays were produced after a double-masked placebo-controlled trial (Ophthal. Physiol. Opt., 1994) had demonstrated a positive effect from coloured filters for some children with reading difficulties. Since the ‘first edition’ was produced, there has been a considerable demand for them from optometrists, educational psychologists and teachers. In addition to the many in use in schools and at home, the Intuitive Overlays have also been used in several research studies.

The intuitive overlays are scientifically designed, based on human colour space. Spectral reflectance curves are approximate