The thickness of the lenses depends on the prescription. If your lenses are thick that means that the prescription requirement is high. If you would like thinner lenses please read the article “what are Hi-Index lenses, and how do I know if I need them? 

If your prescription falls between SPH -4 to -6, we recommend 1.60 Index Lenses.

If the prescription is above -6 and below -10 then 1.67 Hi- Index lenses are recommended.

If the prescription is above -10 then 1.74 Hi-Index lenses are recommended.