I'm dyslexic, which among other things, causes difficulty in reading various fonts or cursive writing. Such as THIS GOTHIC SCRIPT or cursive hand writing where the letters are joined (especially if the writer writes carelessly). Italic writing is also hard for me to decipher. My difficulty with these is not unique to me. Research shows that many with dyslexia or learning disabilities have the same problem, to a greater or lesser degree. So, the easiest reading for us is a simple, printed font, like what you are reading.
There is a school of thought that suggests that designing ‘dyslexic specific’ fonts will solve the problem. Their reasoning is that the eye of a dyslexic will identify the letter better. I’m not sure if I agree with this premise – perhaps they help some. My reasoning is that dyslexia is not a visual thing – it is a brain thing. We can close our eyes (removing the visual aspect) and still transpose numbers or letters if saying them aloud. Research also shows that many students with a learning disability, including dyslexia, have poor word memory. The visual component of a specifically designed font is not likely to be a game-changer for dyslexics.
Yet, I am open to these advances, however more research needs to be done before these new forms are meaningful. For now though, I suggest a simple font, with reasonable spaces between the letters so the letters can be distinguished. But not too wide either, because often the dyslexic brain loses the letter-combination-links if the letters are too widely spaced (for instance, hyphenated words at the end of a line throws a curve ball for dyslexics).
Gray letters, and some other colours can be difficult and exacerbated by the background, especially those with Irlen Syndrome. (Irlen Syndrome is a type of visual or perceptual processing disorder. For more information go to https://irlen.com/what-is-irlen-syndrome/)
Black on white is easiest.
And from this site you will also see that we are of the same opinion that Irlen Syndrome and Dyslexia are not visual issues, but brain issues.