I intend to buy glasses online for the first time some prescription glasses. I have the option of getting a 1.57,1.61 and 1.67... my prescription is -6.25 and -5.75 What index lenses should i go for,please advise.
Thanks.

If you wanna get thinest and lightest lenses,go with the 1.67 high index lenses.You know what,lense with higher index has great advance on lense thickness and selfweight without compromising optical quality.That is why most doctors highly recommend high index lense to patients with prescription above 300 to improve their comfortability of wearing eyeglasses.