Complex sentence: Typically, the patient sits behind the phoropter, and looks through it at an eye chart placed at optical infinity (20 feet or 6 meters), then at near (16 inches or 40 centimeters) for individuals needing reading glasses.
Split into simpler sentences: Typically, the patient sits behind the phoropter, and looks through it at an eye chart. This eye chart can be at optical infinity (6 meters), or at near (40 centimeters) for individuals needing reading glasses.