Additional advise and support can be found at the below links:
There are a few places that you can buy coloured overlays, the test uses the same colours as the i.O.O Intuitive Coloured A4 Overlays these can be purchased at a few places. As well as from a specialist Opticians. Other suppliers will have similar colours but may have slightly different names.
If using a overlay has proved helpful it may be worth considering a pair of Colorimetry spectacles. A Colorimetry assessment with a specialist Optometrist will help to define the exact color to be prescribed. There are thousands of different color combinations so the precision tinted lenses are designed to each individuals needs. For more information visit the Cerium website!