It is best to google www.irlen.com and it's all there. Sometimes it's one colour, sometimes a mix and use of UV filters. One son had 5 colours, the other three and I had 5 plus 100% uv filter.
My new ones have arrived today (they need updating as brain chemistry changes) and it's so wonderful. There is an online test you can take and also someone in your area who will be an official Irlen diagnoser person. =)
Best wishes.
