Are Z87 lenses polybicarbinate? If so, though they may be a stronger material, poly has a tendency to distort and have waves in the around the outer edges of the lens. This inturn can effect your ability to see correctly through that portion of the lens due to the diffusion of light caused by the distortion of the poly lens from it being cut.. When the poly lens is cut, it is stressed by the cutting. This is esp apparent when your script calls for a 6 base optical lens, due to it being a thicker in the middle and thinner out towards the edges of the lens blank. If your script is such that allows your eyeglass maker to use a 6 base lens, you prob better off using contacts. My script is such that I use a 4 base lens, which is a lens of flatter contuor than the 6 base. If your script is -2.00 to -3.00, your lenes are more than likely a 4 base lens. Using standard plastic lenes which are less prone to distortion when the blank is cut for the frames will be fine if you ask for a 3.0 center. Your optician will understand what it is that your asking for. Just to note, I am talking about prescription lens here, not those cheap flimsy sunglass plastic type lens inserts. When I was in the Navy, I was a Aviation corpsman, part of my training was optics. When I got out of the Navy, I went to work at a lens making lab. Meaning that we took the lens blanks from the lens maker, cut the script and prism into the blank (that was my job at 80 - 100 pairs a day), then polish the lens, form cut the lens for fitting to the frames if we provided the frames or if the frames came in from the optician. Back then, a 3.0 lens center thickness was the OSHA min standard for "Safety Lenses". If you were to see my shooting glasses, you would think, dang those are some thick lenses.. and they are, due to the 3.0 center of the lens.