Question: what is the difference between 1.61 and 1.67 index lenses?
Answer: The high-index 1.61 progressive polymer lens covers SPHs of -6.00/+3.00 or lower, CYLs of +/- 6.00 or lower, and an ADD of +3.00 or lower. The high-index 1.67 progressive polymer lens covers SPHs of -10.00/+8.00 or lower, CYLs of +/- 6.00 or lower, and an ADD of +3.00 or lower.