When a doctor diagnoses Diana with retinitis pigmentosa at age fifty-six, her life comes into focus. For years Diana has gone through her days stumbling over things, struggling to find matching oufits and getting into figurative and literal scrapes. Since optometrists assured her that her prescription was correct, Diana had no choice but to conclude tshe was just clumsy and oblivious. Then another doctor said the good news was that she didn't have...