Thickness of Lenses

Hi all,

I’ve been searching places to get new glasses online, and one site asked me to choose a lens thickness and also said if I choose below a certain thickness of (ex. 1.6 lens index, called advanced-thin aspheric), then it may cause blurriness or discomfort due to a thicker lens. Should I go with what they recommend such as the 1.6 index which is for prescriptions between +2.00~+3.00/-3.00~-6.00? (I’m currently at -5.50/-5.75).Will it affect active focus? Thanks and happy new year!


This is the same range that I’m in. My rule of thumb is to go with 1.56 index for sphere values between -3.50 and -5.75. I order 1.61 index for anything above that range, and plan to order 1.50 index for anything below that range.

But I also order frames with relatively small lenses. The wider/taller the lens, the thicker the lens will be at the edges. So this works for me. If I was ordering larger lenses, I’d probably follow the recommendations on the chart below more closely.

FYI, the EM site has a handy visual reference showing how thick lenses will be at different sphere powers and index levels:

You can find that and Jake’s blog post on the subject here: