Resolution when visual acuity is 6/6:
Resolution when visual acuity is 6/6 is 1 minute of an arc. Snellen's test types: The distant central visual acuity is usually tested by Snellen's 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 Snellen's 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.
1 minute of an arc
5 minutes of an arc
6 minutes of an arc
10 minutes of an arc
Optics and Errors of Refraction