Potters & macular degeneration

I am having a terrible time trying to trace my branch of the Potter family, so I am trying a new approach.I know that my grandfather suffered from macular degneration, as does my aunt, who went to the University of Michigan for treatment.She was told there that she is obviously part of a Potter line that they have traced back to some Potter who was an Archbishop of Canterbury.Our branch of the family settled in the Detroit area, but I can't seem to get any further back than g-grandfather Lester Potter, no dob or dod.Does anyone else know anything about this?Thanks.