Apple Distinguished Educator, Matt Thomas, has made a custom keyboard for iOS8, using OpenDyslexic. Below is the description:
Lowercase Keyboard is a custom keyboard that uses both lowercase and uppercase letters, as well as a simplified set of numbers and special characters. The keyboard has been designed with elementary students in mind.
Lowercase Keyboard follows the layout of the default keyboard closely so it is easy to use. The font of the Lowercase Keyboard is "OpenDyslexic" which has been created to increase readability for readers with dyslexia.
Absolutely no information from using this keyboard is collected or stored. You can use Lowercase Keyboard without worrying about your privacy or the privacy of your children being compromised!
I have created this keyboard for my own classroom, and know it is very beneficial for my students. I hope you enjoy using Lowercase Keyboard too!