Prescription safety glasses are not the same as regular prescription glasses. In general, prescription safety glasses are more difficult to process and more complicated to make.
Making Prescription Safety Glasses
There are a variety of parameters that need to be taken into account before a pair of prescription safety glasses is even started in the lab, and then the process in the lab differs from normal prescription glasses when it comes to lens curvature and edging. If you’re wondering how your prescription safety glasses will be made, here’s how we do it:
First, we check to make sure your prescription will work in the frame. We do have limits on our web site, but certain types of unworkable prescriptions can get through on some of our safety glasses. Prescription strength must be weighed against lens curvature and pupil distance must be weighed against lens type and size to determine if your prescription will work in a safety frame.
Once the prescription is approved, the glasses go into the lab. The appropriate lenses are pulled and placed into the tray with the frame. Progressive polarized polycarbonate semi-finished lenses are an example of the type of lenses that are pulled. Lens diameter and curvature of the frame must be taken into account when pulling lenses.
With the lenses in the tray, a technician enters all of the prescription information for the job into the lab’s computer system, and that same person traces the frame (using an advanced lens pocket tracer) so the lens shape is saved in the database with the prescription.
Next, somebody prepares the semi-finished lenses to have the prescription generated into them. This requires taping the lens front to save it from scratching, attaching a double-sided sticky pad to the front of the tape, and attaching a clip to the other side of the tape. This allows our machinery to hold the lens by the clip without damaging or scratching it.
The first step in the actual creation of a prescription is generation. A technician will load your job’s details into our prescription generator, place the lens in the machine, and run each of the pair of lenses to cut a rough shape of the prescription into the back of each lens.
Once the prescription is generated, the next technician does a rough polishing of the lenses using polishing tools with sandpaper-like pads ttached to them. Each “tool” is shaped to a specific prescription, so it literally sands the prescription into the lens. This is done in several steps with increasingly finer pads (this process is called “fining”), until the last pads polish and buff the final prescription into the lenses.
The prescription is checked here to ensure that it is correct. If not, the job is started over.
After fining and polishing, the lenses are coated with scratch coating (if applicable).
Next, the lenses are placed into one of our advanced CNC edging machines. These machines have the lens trace (from step 3) loaded into them, and they edge the lens to the frame shape while taking the pupil distance, segment height, lens diameter, and optical center all into account.
After edging, the prescription is checked again.
Once the lenses are edged, they are tinted, sent to get anti-reflective coating or mirror coating, and/or shelved for a facial cavity seal gasket (as in motorcycle glasses), if applicable.
The lenses are then inserted into the frame.
Finally, the lenses go to final inspection, where the prescription and health of the lenses are checked for a final time. If there are any imperfections in the lenses or frame, the glasses fail quality control and must go back several or all steps.
After inspection, the glasses are carefully cleaned and packed, and our shipping department sends them to you!
We hope this gives you a good idea of what happens when you order a pair of prescription safety glasses from us. Our process is designed to be streamlined and to make each pair of glasses a team effort. Our dedicated and experienced team processes many prescription jobs every day, and we take the utmost care of your lenses to ensure that you get a pair of glasses you are happy with. Our repetitive quality control measures ensure that shipping defective glasses is as rare as possible.
If you have any questions about your glasses or the process, please don’t hesitate to give us a call or leave a comment below, and thanks for reading!
