You might want to Google the " Americans with Disabilities Act " and "reasonable accommodation" . The employer can choose to not hire you, or move you out of a job position IF they cannot reasonably accommodate you due to your disability; however, this is only true if your disability makes you unable to perform a Bona-fide Condition of Employment that comes straight out of the job's Position Description. Do these conditions apply in your situation?
As far as affecting performance evaluations, it isn't really legal for the disability to affect this one way or the other, you are either qualified for the position and performing the task, or you aren't.
