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!

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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:

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