I realize that many (if not most) of the Instructables audience will be too young to need these, but keep it in mind - sooner or later, you will.
I'm 40 years old and I've worn glasses for nearsightedness most of my life. I'm past being too concerned about looks and contacts are a hassle, so I've stuck with glasses. I have a pair of thin metal framed, small lens glasses that I like a lot. Recently, within the last year or so, I've realized that time of my life has arrived where my arms are getting a bit too short to read comfortably and my really cool new laptop with a 1920x1200 resolution has text that is a bit hard to read when it is sitting on my desk. It's not like I'm completely farsighted (yet), but after a bit, I start to get eyestrain and I read and use the computer a lot.
I'm not ready to get bifocals. I don't really need them and I don't want larger lenses in my glasses (besides, I'm getting old, but I don't want to *look* old). I tried on a low powered pair of reading glasses, over my real glasses, and said, "Wow. That's much better." Of course, wearing two pairs of glasses makes you look a little deranged. I have nifty little spring loaded polarized sunglasses that I bought at Wal-Mart that match my frames so I thought, I'll bet someone makes the same thing in reading glasses. I looked, albeit not very thoroughly, and the best I could find was ones that clip at the top of your glasses and can flip up out of the way. My dad had pair of sunglasses like this back in the 70's and they look a bit dorky.
So, I had just bought a new pair of sunglasses because the lenses in my old ones were scratched and I decided that I would just transplant the lenses from a pair of reading glasses to the sunglass frames. Yes, this would look dorky, too, but at least it would be something that I made and invented myself.
Step 1: Materials Needed
Pair of clip on sunglasses that fit your current eyeglass frames. These can be spring framed, spring loaded, magnetic, whatever. These usually are made for metal framed glasses, although some (particularly the magnetic kinds) are available for plastic.
Dissassembleable reading glasses in the proper diopter. Most stores that sell them have a little reading chart so you can try out the various strengths. If you don't use them already and just think that you might need to (like me), you probably only need +1.00. They go up +3.00 or more. The cheapest ones are only a few bucks, but you probably won't be able to remove the lenses. I bought a metal framed pair (see below) that were rimless and held together by screws. An even better alternative might be to hit thrift stores or yard sales and find a pair. Then you could be more experimental in removing the lenses.
I got smaller reading glass lenses that I needed because my first thought was to make them bifocal like by just mounting the lenses at the bottom of the frames. It turned out that the added distance between the lenses distorted the view a bit, so I wound up centering them.
There is still room for experimentation on bifocal style, but if you're going to mount them centered like I did, then your goal should be to match the size and shape of the reading glasses lenses to the sunglass frames as closely as possible.
Small pliers, eyeglass screwdriver (or a Swiss Army Knife), tape or wire, and glue (I used cyanoacrylate, but there are probably better choices - and I would love to hear of suggestions)
Step 2: Disassembly
Remove the lenses from the sunglasses. For the ones I used, the lenses are thin plastic and can be popped out with a little force without bending the frames.
Disassembly of the reading glasses will depend on what type you are starting with. For the ones I used, I removed the ear pieces, then used pliers to unscrew the nuts holding the lenses to the frame pieces. If you are a pack rat, you can save the screws, nuts, washers, and frame pieces for eyeglass or jewelry repair or to build a mouse robot or something.
Now would be a good time to clean everything really well. You'll probably still get fingerprints on them during the next step, but you want to remove grime, oils, etc. before fitting and gluing.
Step 3: Test Fit (semi-optional)
I had already put the reading glasses on over my regular glasses to see if the idea even worked at all, but I was anxious to try the "finished" product without gluing them together, so I did a test. My lenses have holes in them where the screws were mounted, so I used some thin wires to twist-wire them onto my frames. I left the wire on for the next step to hold them steady while the first contact points were drying. You can also use small squares of cellophane tape to hold them in place temporarily.
You want the lenses to be as close to your glasses as possible, perpendicular to your field of vision, centered over your eyes, and relatively level. For some types of frames, you must also take the flex of the frame into consideration to keep them square.
I tried them on reading my super-duper high resolution monitor and they worked great! Now I just needed to mount them permanently.
Step 4: Glue
Depending on the fit of the lenses to the frames, you should have at least four contact points between the lens and frame. These are the points you want to glue.
I used cyanoacrylate (CA or Krazy Glue) because it was fast and I had some. In retrospect, I should have used something else. I got just a bit of hazing on the lens edge at the glue point. Any glue that will bond to the metal or to the plastic should work fine since there is a bit of mechanical joinery involved. If anyone has better suggestions or tried this with other type glues, let me know. If I make a better pair, I would do the gluing differently.
Since I had my lenses wired to the frames already, I glued the bottom two contact points first and let them dry for a bit before I removed the wires and glued the tops.
Don't glue the tape or wires to the lenses or frame!
Don't get glue on your fingers and touch the lenses unless you want permanent CSI-style fingerprints on the lenses!
Make sure the glue is set before trying them on unless you want a permanent pair of four-lensed reading glasses!
Step 5: Use Them
Once the glue sets, give the lenses a quick buff and try them on. If you're at the point where you need them, the difference is amazing.
Depending on how well you chose your lens sizes, i.e., if you did better than me, they shouldn't look too dorky. Reading and computing are usually pretty solitary affairs, so who is going to see you anyway? Above all, these should do you until you bite the bullet and go get fitted for bifocals (or trifocals,
If you don't need reading glasses, then why have read so far? Actually, if you don't need reading glasses, you might want to use this technique for mounting other things to your glasses - magnifying loupes, HMD mirrors for VR overlays, etc.