Take this poll.
If you answered a. You might as well move on. But if you answered b or c then this video is for you.
The dreaded figure eight replacement in metal nylor frames, the when and why you should do it.
When: When the plastic inter liner above the lens is broken or missing replacement will give the lens a snugger fit keeping the lens in place. You my hear this from the patient, “this is the third time I’ve brought my frame in to have this lens inserted, it keeps falling out.” On close inspection you may find the figure eight chord is missing or only partially there. That’s a sign that tightening the bottom string has not been effective in previous repairs and it is time to investigate the figure eight chord.
why is it called the figure eight chord. See picture
Why: Obviously the repair will make your patient happy when the lens remains in place and never falls out again but most importantly the figure eight chord acts as a cushion for the lens and prevents lens from chipping and flaking at the top of the lens especially in CR 39.
The chord is like two in one the top is smaller version of the bottom. The smaller side goes in the upper eyewire groove,the larger portion is on the outside. And yes the figure eight comes in multiple sizes. See picture.
When the correct size is chosen then the only tools you need are a stick pin such as a tack and the frame air heater you can watch this video to see how it is done. Note it is not fast and usually not easy but the more you do the better you will feel at out doing them. For how to do this watch the video. Comment below if you have any quick and easy tips to expedite the repair process. Thanks!