Money saving advice to anyone who uses #zenni #zennioptical especially those that have high prescriptions. The recommended Index is not required. You'll hear a lot of talk about how the glasses will be too thick and that's just an outright lie. One of my eyes is -6.25 and the difference between the opposite ends of lens index is negligible.
Save yourself the pain and just go with the half price option and while you're at it skip the crazy blue light filtering and other add-ons that don't do anything for your eyes but confuse your color perception.