Writing for dyslexics

I want to write a letter to an adult friend who has dyslexia. The subject of the letter is quite complex and I want to give her the best chance to understand it without too much frustration. There must surely be ways to structure writing which will help.

I googled but could only find advice for dyslexics in doing their own writing. Can anyone give me some tips, or point me at some resource?

There’s a font called OpenDyslexic designed by dyslexics to improve legibility. A relative of mine uses it.
Unfortunately dyslexia takes many forms so it’s hard to answer your question more specifically.

When describing her dyslexia my friend says she has no trouble reading the text, so special fonts are probably not the solution here. She does report that to her words are transformed into images in her mind. Those words that don’t readily conjure up an image cause her problems and she loses the meaning of sentences.

Every dyslexic is different, but as a dyslexic myself I find “clearness” in texts very useful, so I’d suggest things like

[ul]
[li]Clear handwriting / sans serif font[/li][li]Clear language[/li][li]Good spelling and punctuation[/li][li]Simple structure; eg paragraphs for each change of topic[/li][li]Bullet points for lists (see what I did there!)[/li][li]You might also want to consider putting it on pastel coloured paper to make it easier to read - (I like green myself) but its personal preference.[/li][/ul]

I find it easier to read if the writer sticks to short sentences. I also tend to lose my place, and using double-spaced (or 1.5x spaced) lines helps a lot with this.