<prompt> What is the angle subtended by the topmost letter in the Snellens chart at the Nodal point of the eye when the person seeing it at 6m from the chart?5 min10 min40 min50 min  <response>: The topmost letter subtends 5 min at Nodal point of the eye when viewed from 60 m.So the same letter subtends 50 min at Nodal point of the eye when viewed from 6 m By cross multiplication. 