If you have 'scratch proof' lenses there should be a warranty on lenses regardless of manufacturer. Industry standard is either 6 months, 1 year, or two years,

If you have 'scratch proof' lenses there should be a warranty on lenses regardless of manufacturer. Industry standard is either 6 months, 1 year, or two years, and that is probably the greatest value in comparison rather than the nominal difference between hardness. Also any good optician will only say 'scratch-resistant'.