We get regular queries from customers about base curve. What is it? Is it very important? Can I change mine? Base curve measures the radius of the sphere of the back of your lens. In everyday speech, it measures how tight or loose your contact lens is. Some wearers can tolerate a range of base curves, others can not. If the base curve is too small (or steep), you may encounter difficulty removing or inserting your lens. If the base curve is too big, your lens may feel loose or that it is ‘slipping’.
Think of base curve like a shoe size. You can most likely walk in a shoe not exactly your size but it may not be the most comfortable. The same goes for base curve. If you want to wear a lens that does not match your prescription exactly, talk to your optician first.