No matter how talented they are, adult dyslexics are often secretive and defensive. They write down inverted phone numbers and financial figures. They can spend an hour trying to decipher a memo. Many get headaches from trying to read accurately. The loss of productivity is difficult to estimate, but is obviously enormous.
Employers can easily adapt the workplace to help reading disabled people to work more efficiently.
Give instructions orally or dictate them onto tape or voice mail. Have someone read things to them, or get a voice synthesizer for the computer and let it read the memos. Dyslexics are usually good with computers. Those who haven't had remedial training are at a disadvantage, but they do have accurate, detailed memories. Question them orally or let them dictate answers so someone else can else can fill out the forms.