Isaac Lidsky’s career trajectory began at the age of six months with a diaper commercial, the first of many show biz breaks that included playing geeky teen Barton “Weasel” Wyzell in the ’90s TV hit, “Saved By The Bell.” Next stop: Harvard, where he graduated at 19 in Mathematics and Computer Science and then tacked on a law degree that led to a successful internet startup, a U.S. Court of Appeals clerkship, a three-year stint on the Justice Department’s civil division appellate staff, an associate’s position at the tony Jones Day law firm and, most recently, a Supreme Court clerkship (for retired Justice Sandra Day O’Connor). We wouldn’t have mentioned his invitation to pitch the first ball at the Florida Marlins-Chicago Cubs game last September except for the fact that Lidsky, 29, has suffered from retinitis pigmentosa since he was 15 and has been legally blind for five years.