<prompt> Resolution when visual acuity is 66:1 minute of an arc5 minutes of an arc6 minutes of an arc10 minutes of an arc  <response>: Resolution when visual acuity is 66 is 1 minute of an arc. Snellens test types: The distant central visual acuity is usually tested by Snellens test types. The fact that two distant points can be visible as separate only when they subtend an angle of 1 minute at the nodal point of the eye, forms the basis of Snellens test-types. The lines comprising the letters have such a breadth that they will subtend an angle of 1 min at the nodal point. The entire character optotype subtends an angle of 5 min of an arc at the nodal point, each stroke is 1 min at the nodal point. 