Eyeglass repair--broken monofilament lens retainer

Picture of Eyeglass repair--broken monofilament lens retainer
I was sitting on the sofa reading and my right lens suddenly dropped onto my lap without warning. The monofilament (fishing) line broke from several years of normal wear. I was very thankful this did not happen while I was doing quite a number of other things I normally do, like riding my bike on a country road.

It was the weekend and my optometrist's office was closed. I am a pastor and had to lead the worship service on Sunday without my glasses. There is a lot of reading involved. I got by with a pair of reading glasses, but everything more than fifteen feet away was a big blur.

I searched the Internet for eyeglass repair. There was nothing about replacing a broken monofilament lens retainer.
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Step 1: Anatomy of an eyeglass frame

Picture of Anatomy of an eyeglass frame
The parts of an eyeglass frame where the monofilament line attaches to hold the lens are very small. The colors of the frame and of the line blend into one another much more than shown in this drawing, especially when you are looking at them without your regular glasses.

The left portion of the drawing shows the end of the frame if the glasses are upside down on a countertop as in my first photo and you are viewing the frame from the side where the bows attach. There are two small holes near the end of the frame. The monofilament line loops through these holes. The 90 degree bends the line must make keep the line from slipping when the lenses are in place. The graphic in the next step will give you a clearer picture of how that works.

The right portion of the drawing shows a cross section of the metal in the frame and the channel on the inside of the frame where it contacts the lens and supports it. The gray circle is a cross section of some monofilament line permanently embedded in the frame. There is a corresponding groove around the circumference of the lens and that groove fits over the embedded monofilament line to keep your lens in place where the frame goes around the lens.
vanzilar2 months ago

I love these glasses, and it took 2 years to buy them, they survived world travel, crushing weights, and near destruction (aka they were trapped under an upside down car and buried by it for a week before being recovered and still no damage), and were still ticking.

After all that abuse of my glasses (when the glasses were 10 years old) the line broke when cleaning!

This post is so cool. I wanted an eye-doctor guy to do it for me and to just pay him, but my wife insisted I try self repair. Found this post, and took awhile to find the right line. After going everywhere went to Walmart and found matching 30 lb Omniflex .023 mm line. It took about 15 min to thread but a perfect repair at the end with the same strength, color and feel as the original. Your post is amazing is how well it explains why I thought would be impossible to do and makes it very easy.

Phil B (author)  vanzilar2 months ago
Thank you for the good report and congratulations on your success. I hope you are now a giant in your wife's eyes.
racox2 years ago
Nice! I broke my glasses last night and spent about an hour straightening the frame but figured I'd have to pay big $$ to get the lens put back. Now, with a few inches of 30lb test line from Walmart, I'm good to go! Thank you for putting these instructions up! Total cost for the fix... $1.99!!! And it only took about 5 minutes!
Phil B (author)  racox2 years ago
Thank you for commenting. I am glad this helped you.
danray35e3 years ago
I inadvertently left my glasses sitting on my dash board one hot day, and came back to find that the heat caused the lens to expand, popping the mono-filament.
I had bought them at walmart eye clinic. I took them in, and they fixed them while I waited. I had no idea the lens was held in place by monofilament before that happened. Your instructable will come in handy one day.
Phil B (author)  danray35e3 years ago
Thank you for looking at my Instructable. It is good you were able to have your glasses fixed easily. When mine failed, no such stores, especially the one I use, were open. For times like that some fishing line in the workshop is handy. The one difficulty I experienced is that it is difficult to see without your glasses while working on your glasses. I had bought some reading glasses for use in pistol target shooting, and they helped a great deal, even though they were not perfect.
mooseo4 years ago
Great instructable. I'd just like to add something that wasn't totally obvious when I first read it...

On mine, one end looked just like yours, and the line went in and out and tucked under the lens. On the other side, though, the line just went into a hole and stopped. It wasn't clear how this line stayed in place. I pulled the fishing line through this hole, then heated the end with a lighter and tapped it against the desk to flare the end. That seemed to hold just fine while I tensioned the other end as described.
TheThirdMan4 years ago
I'm an optician, and I'll say you've come very close to what we do. I would offer a couple of suggestions in case this should this ever happen again. By adding these simple steps, you'll get the lens in there as tight as day one.

When you have first threaded the line through to size it up for length, place the lens in the frame (and the line into the groove along the lens' edge). Now, pull the line as tight as you can within reason. You should be beginning to actually stretch the line a tiny, tiny bit. While keeping the tension, pull the line at a sharp angle so that it makes a slight kink in the line.

Release the tension and remove the lens. The kink should still be visible and can now serve as a marker. When you insert the line through the second hole to secure it, feed the kink through that second hole a few millimeters so that it just comes out on the inside of the frame. This will ensure that the hold will be slightly tighter than when you were applying tension.

Now use the ribbon method mentioned earlier. All you do is put the lens back into the frame and pull the line up over one corner of the lens and into the groove. Next, take a three or four inch length of satin ribbon and loop it around the line. Use the ribbon to pull the line over the edge of the lens and the line will snap tightly into place. Afterwards the ribbon should slide right back out by pulling on one end.

One word of caution: If the line is so tight that you really have to pull excessively hard, take a step back and loosen the line. If you go crazy and make the line ridiculously tight it can chip the lens edge when you force it over. Keep in mind, you should have to use a good bit of effort to get it over, just don't go overboard.

Another little trick if it is still a little loose after all is said and done: (Leaving everything assembled as it is) Heat the line for about thirty to forty seconds with a hair dryer on high. Immediately afterwards, dip it into ice water. This will tighten it right up. As long as you live in the U.S., this will not damage the lens (they go through much harsher temperature changes during production). In Europe or Asia, however, do this at your own risk. The standards for treating glass are much different overseas. The upside is that they can get glass much thinner than we could ever dream of here. The downside- it does not take much to shatter it. Also, an optician in the U.S. would lose his license for putting a glass lens into a semi-rimless frame like this. On the other hand, it is still very common to see it done in Germany and Italy. I've also seen one done in Hong Kong in which the lens was barely wider than the line. It was a very impressive piece of craftsmanship, but I would be terrified to wear it.

Also, just so you know, most opticians should make this repair for you at no charge. They may not be thrilled about it (it is fairly time consuming for a busy practice/lab), but most will do it with a smile.

One last point- The "Sarah Palin" style frames (it is incredibly annoying that they have been so thoroughly connected to her, in reality they've been around for decades) actually don't use a groove-and-line system like this; the lenses are actually drilled through and mounted with screws. Just so you know.

Hope this helps in future dilemmas.

Phil B (author)  TheThirdMan4 years ago
Thank you for your detailed and informative comment.  Thankfully, my lenses are plastic, not glass.  As I mentioned, this problem developed for me on a weekend when all of the shops were closed and I needed glasses early the next day.  I posted this for the benefit of anyone with a similar problem, but unable to get to a shop for a repair.
it's polycarbonate plastic, a plastic used in CDs and bulletproof windows (except the one that nasa uses, those are silica-fused glass)
incentiv6 years ago
I have a pair of glasses just like it with a broken foot/leg? (what goes over the ear). It's broken at the hinge. Can any body help?
We call it a temple. Unfortunately, if the hinge itself is broken, there is not much that you can do. On most frames the parts in and around the hinge are too small for even a jeweler to solder and still keep functional.

Your best chance is to see if the frame is still current (as far as production) and try to order a new temple or frontpiece- depending on exactly where the hinge is broken. Cost-wise it will usually set you back about 1/4 to 1/3 of the original price of the frame.

Before you do that though, make sure that it is not just a problem with the screw. I know that sounds ridiculous, but on some of the more intricate frames, people commonly assume that the hinge is broken but it turns out to only be a missing or defective screw. Best of all, that repair is free.
nemo46 years ago
contacts are way better
omnibot6 years ago
Why do pastors and missionaries often use those glasses that have no rims on the bottom? I remember Douglas Addams making an observation about this in the book "Last chance to see". Anyway, good instructable.
Phil B (author)  omnibot6 years ago
Oops! I misunderstood. I thought you meant the little half glasses people wear on the end of their noses. Then they look over them. My glasses have no frame, but monofilament line, on the bottom because that was what my optician was pushing the year I last got new frames.
Phil B (author)  omnibot6 years ago
You ask good questions. I would not go near them, myself. People who wear those always appear to me as pretentious and condescending, even if they would definitely not be those things. It was, however, tempting to wear my reading glasses that way this weekend. I would have been able to see near (through the glasses) and far (above the glasses).
Cornflower6 years ago
It seems to be the IN thing right now in the US, the Sarah Palin look. I don't think she is a pastor.
Eyeglasses is very very expensive in UK, but much much cheaper in China. Crazy expensive!
idoodit6 years ago
I'm in the Optical business and you got it right on fixing you frame,also you can heat the line with a lighter,do it quickly so not to burn the line, and it will shrink then use the ribbon method.
Phil B (author)  idoodit6 years ago
Thank you for your comment and your helpful information. Although the concept is not complicated; the parts are so small, even with a magnifying glass; that is took looking at my frame and thinking about it over most of 24 hours before I was pretty sure of what I was doing. The results pretty much confirmed that I was on the right path in my approach to the problem.
iskandr6 years ago
You can make the lens tighter by using a shorter line then using a small piece of ribbon to pull the line into the groove cut on the lens.
Phil B (author)  iskandr6 years ago
Excellent suggestion! Thank you.