According to your question, I can see that your prescription is a little bit strong. However, even though you have strong prescription, 1.60 index lenses/1.67 index lenses are enough for you. Between 1.60 index lenses and 1.67 index lenses, the former is a little bit thinner than the later with the same prescription. However, personally I think 1.60 is enough if you do not pursue thinner lenses. Moreover, there is no 1.70 or 1.74 polarized high index lenses because they are never existed. To know whether the polarized high index lenses are right for you or not, you need to know whether you are sensitive to bright sunlight? Are you using the glasses for fishing, boating or skiing? Will you rarely use electronic with your glasses? Do you experience problems with reflected light off of cars or water? If all these above answers are yes, then polarized high index lenses are probably right for you. If you answered no to most or all of these questions, it's worth considering a different lens color or a different lens material.
