Is it possible for someone with mild marfan syndrome and perfect eyesight with no dislocated lens be a pilot?

Yes: A person can be a sport pilot if he is in good general health and has no problems that would make it dangerous for him to fly (a medical exam is not needed). If one wants to be a commercial or airline pilot, medical exams are needed. If one's eyes are fine, there may still be questions about the risk of aortic rupture. One should read up on the faa rules before seeing an aviation medical examiner.

Yes: A person with marfan's would need to meet the same standards as anyone else. The diagnosis of marfan's syndrome would not automatically disqualify a person.