En garde, mon fils, tu vas blesser ton oeil! If Mme. Braille had recited this mother’s mantra to 3-year-old Louis before he went to play in his father’s harness shop that fateful day, her son might never have grown up to develop a practicable system of the raised-dot communication invented by Charles Barbier. Playwright/director Andrew Martineau’s The Dotted Line connects Braille’s life—student, teacher, early death from consumption—to the story of Brian, a modern-day architect struggling to deal with macular degeneration. With the aid of a projected diagram of the eye, the audience learns about this common cause of blindness. And en garde, mes amis. As Martineau says, “Macula is not to be confused with spatula.” Follow The Dotted Line when the show starts at 8 p.m. (to Dec. 14; see City List for other dates) at Theatre on the Run, 3700 S. Four Mile Run, Arlington. $10. (703) 455-1877. (Janet Hopf)