On contact lens sizing - what is "SAG" - instead if the normal "BC" My new lens RX has a SAG of 3.75

Question

On contact lens sizing - what is "SAG" - instead if the normal "BC" My new lens RX has a SAG of 3.75

Answer 1

What kind of lenses were you prescribed ?

The SAG, or Saggital Depth is the actual depth of the lens when measured from the edge to the apex... It has a relationship to the base curve, but it takes a lot of detailed calculations to determine the BC from that.

That is normally only used as part of the calculations in making Ortho K lenses and some other types of custom crafted lenses.

If he wrote that on an Rx for soft lenses , it was just to make darn sure you can't order online....

Answer 2

To go along with footprint. There are certain brands of contacts that use that to that aren't custom made but it's very rare. What brand of contact did your doctor put you in?

If your doctor did put you in a lens that comes with a standard b.c. and just wrote that on there to make sure you can't order anywhere that is against the "Fairness to contact lens act" Doctors have to provide you with a valid copy of the prescription and allow you to order where ever you want.