This was pretty neat. I have worn glasses for 30+ years and never has anyone explained what all of these numbers meant until now when a woodworker showed me.

Next week - DIY hardwood hip replacement

OK, this is prime Random Stuff material. I'm in for this.

I’m an optometrist and I liked this video a lot. I always like Matthias’ stuff. In this case he has made the process quite simple and it seems to work for him but his is a simple case it is really not that easy in many cases. For example, if you employ the maximum plus power spherical lens then you don’t always have to compensate for for that when deriving the negative cylinder, but you do if you are using positive cylinders. Also, the balancing technique is unreliable when the vision is a bit worse, or if you are younger. No testing was conducted for eye movements either, which can wildly alter the final prescription. Balancing all of these features, understanding their relationship to each other and considering the implication to health is the difficult bit.

I would certainly like to see you make more content on this topic. Having multiple family members who are optometrists, and being an engineer myself, I am often told "engineers are the WORST patients". I believe we likely indeed are, but that is because I like to understand what someone is doing and what they are looking for... instead of the typical "which is better" because it is not always a simple answer.

« Matthias is like a box of chocolate, you never know what you’re gonna get. » Bring it on, it’s always fun to follow along.

I'm fascinated that you can make a video about almost anything and make it interesting :)

Many moons ago, I used to work overnight maintenance at a large American retailer with an optometry service. Every so often the floors needed to be redone in there and while waiting for the floor finish to dry between coats I got to fiddle around with all the equipment and ended up prescribing myself contacts - which I had never previously worn. I nailed it I guess because when I went in a few years later to get them legitimately - the prescription was the same! Fascinating topic.

I've worn glasses all my life, but I'm a procrastinator so I sometimes went over 5 years between eye appointments. My last exam was in 2016, and then along came the pandemic so I found myself in 2022 struggling a bit with my current prescription. So I went the same route, I purchased a lens kit on Amazon, along with a "nicer" trial lens frame because the ones that came with the lens kit was kinda like yours. Anyway, since I already had my prescription numbers from 2016 it gave me a nice starting point which made it easier to tweak my prescription. I have astigmatism, and that turned out to be the setting that changed the most and cleared up my vision. Because I already had a base prescription to start from the process was much easier for me, at least. I then took my updated numbers and ordered my lenses online, sent in my frames and in about a week I had my new glasses. So much better now! I will still see try to see an optometrist this year anyway, because it's important to actually have your eyes checked by a professional for signs of diseases, such as Glaucoma, Cataracts, etc.

Getting your eyes checked for free at Waterloo was quite a good perk for us when we were students. Now that I'm a senior I can finally get them checked for free again.

Ive been doing this for myself and a few friends for about 10 years. I got some much welcomed relief from headaches by intentionally under-correcting long distance vision to 20/30 instead of 20/20. As a side benefit to under-correcting, within a month my vision improved by a diopter. I have a large set of trial lenses so that I don't need to stack lenses, and I have a set of plastic trial frames for different eye spacing, which is very important for my stronger lenses. My vision is affected by MS, and being somewhat under corrected, and having the right slightly under-corrected RX for near, mid and long distance tasks has been very helpful in reducing headaches. Zenni has made this experimentation affordable for me. The process is pretty easy, as you have brilliantly and briefly demonstrated. Great work, Mathias!

Dear Matthias, we all have an inner optometrist trying to get out. Newton would be proud of you. Best wishes, John

I think what's most enjoyable about the video is that you aren't an optometrist. I think what's been the most interesting has been that you have your methodical engineering mind, and it's interesting to watch, as if you are sitting in on a lecture almost. Even if it's not this subject, random dives like this are extremely fun from the viewer perspective!

Very interesting. I had never thought much about what the specific numbers to my prescription actually mean. Cool experiment to see it done "manually".

Bringing the excellence of Matthias' curiosity and thoroughness to a topic I knew nothing about, but have become more interested in now that I too require glasses for any kind of detail work. Thanks for taking the time to make this video and explain it.

You're making me want to buy such a set just for fiddling. I don't even have glasses

Very interesting. When everything was in lockdown, I realized I was going to be making several cross-country trips to see my ailing father. I've never had glasses, but at my age (55) I was suspecting some distance issues (evident while driving) that I never had before. I ordered a device called EyeQue that Bluetooth connects to your phone, you stick it to the screen of your phone and the app displays a series of different colored lines at different angles. Buttons on the device, adjust the relationship of those lines (via Bluetooth) and after a series of tests in each eye where you align the lines it returns you prescription. I bought a cheap pair of glasses online using this prescription to try and holy cow I never realized what I couldn't see. I've since used that prescription to purchase some better glasses and use them whenever I drive to great advantage. I'd love to see a comparison of how these types of devices compare.

I made eye glasses in the Army so it was interesting seeing you learn your way through.

I'm a trained optometrist so this was fun to watch. You've clearly done some research and are kind of doing the type of basic refraction a new first year student would do. You certainly wouldn't pass any exams or anything, but I was surprised to see you compensate the sph based on the cyl for example. Obviously I need to say please please please don't do this in lieu of getting your eyes checked properly. I have access to equipment worth north of 100k, plus I actually know what I'm doing - I don't even test my own eyes. It's not all about simply comparing lens A with lens B. With the key caveat that this is just for fun and you're not going to skip seeing a professional, there's a few things you could do with that basic kit to refine things a bit: You could print off a fan+block chart to get the cyl a bit better without a x-cyl, implement some simple checks to avoid easily over-minusing (+1.00 blur is enough but duochrome is interesting once you learn how it works), maybe use Humphriss immediate contrast when binocular balancing at the end. That trial frame is also annoyingly useless. You always need a way of centering the lenses.

I did not see this video coming.

I am very nearsighted and have often wondered if I could do as good or a little better than the eye doctor in setting my prescription. Great topic so keep up the great work!!

Very interesting and relevant, thanks. This time around I tried one of the internet glasses companies, and took my updated prescription and was amazed at how good the glasses were and how useful it was to get reading, computer and distance glasses as I would normally have used up my budget just on one and not got the experience of all three. I only tried one internet retailer, and leaned heavily on reviews for frames, but I was happy with my test sample of one vendor, I suspect they are all pretty similar quality and will never go back to a store for glasses.

I wasn't going to watch this really but now that I've clicked it and heard how much you've spent I have to watch the whole thing and give it a thumbs up. The man's got kids he needs to feed...

Any video you post, I watch no matter what. The amount of things I have learned from you that I never knew I needed to learn. Keep up the random videos like this!

i remember the sad day i walked out to the garage and couldn't read the tape measure anymore... had to get some reading glasses. good video and info.

This was really interesting! Thanks for the short overview of the process.

I have always wanted to get a set of trial lenses like this to see whether or not my prescription needs to be updated and also to experiment with different amounts of magnification for close-up work. I'd definitely like to see you talk more about this =)

I wouldn't have guessed this could be an interesting topic, but here we are. I learned more from your short video than from a lifetime of optometrist visits. This was way cool. I hope there's more to come.

Is there anything you don’t know, amazed at your knowledge ❤️😊

Once again you have clearly explained something I didn't know I wanted to know. Matt, you are a phenomenon. Thanks again for a great video

I found this very interesting. I have often thought that there is nothing mysterious to measuring eye sight for prescription spectacles and you have demonstrated that is the case.

Really going all in with the mad scientist look. I dig it!

This is my favorite of your videos in a long time.

I've never really been happy with my prescription after my first pair where I discovered you can see leaf veins on trees while being 20 feet away. The back and forth evaluating for only a few seconds never gave me confidence it was correct. Darn you Matthias, for now I have another thing I must DIY instead of leaving it to the professionals! Excellent explanation and video. Thank you.

This was honestly really insightful! I'd watch more of this. I don't really know much about this stuff either, but I definitely felt like I learned at least a little bit.

I am still fairly new to needing glasses, so this was really interesting. Keep meaning to see if anybody has tried making their own glasses, as that would be interesting too.

I would enjoy more videos on this (or other subjects) from your perspective. 🙂👍

I loved this subject! You come up with amazing project ideas

I happen to have an eye appointment to tomorrow. Maybe I’ll bring this video up and suggest I skip my next appointment just to see the reaction that gets me 😂

This was your most interesting video in a while. Keep it up. Odd tech is great

Man, what a box full of surprises, this Matthias! Great to see these random topics without the umbrella of the "I'm an expert"

Yes please, more on this subject. Thank you.

So my uncle who married into my family, comes from Croatia. He went to the optometrist, and the optometrist asked him "Can you read the 4th line?". He replied "Read it? I know him !"

OMG it was so interesting to see what's happening between all the lens flips, and why they go back and forth so much (spherical, astigmatism, balance), AND what the numbers really mean!!! Thank you, and I'd love to see another video with more info, of COURSE!

A a fellow bespectacled human, this is really interesting, as usually, doctors are busy and don't really explain what they are doing or very well. I would love to know more, as it would make me a better patient and help the doctor with better care. We can all stand to learn more about our own healthcare.

I saw this on Instagram and couldn’t wait for the video! Very interesting to see the geometry behind it.

I appreciate seeing you do this, it helps clarify exactly what is going on when I see my optometrist.

What an interesting rabbit hole. Please do some more on this topic.

Fascinating stuff. I've never needed glasses so I've always wondered why prescription glasses were so damn expensive. Turns out there's a lot more to them than I thought

Always interesting to watch your videos. A word of caution. Opticians do retinal examinations and check for glaucoma. I’d still get my eyes checked professionally even if you are confident of producing the correct prescription.

Amazing, the understanding you have of multiple subjects

Very interesting. I'm not an optometrist myself but worked for one for three years and used glasses for 20 years before I got LASIK. Many of your points are correct and good, but to check for the cylinder you need a different eye chart. I do believe it looks like a set of crossing lines, but I am not sure how to read it and can't find it online at the moment. There is a personal point I'd like to make though. While it's a great skill to have and delivers tons of nerd points to be able to do your own prescription, a master optometrist have knowledge that can benefit you apart from getting a potentially more accurate prescription. It's been 15 years since I worked at the optometrist but back then it was said that almost everything they taught at school was how to spot various illnesses in the eyes. Making prescriptions was taught when they started working, and contact lenses were an additional course. A optometrist who is proud of the profession and own a medium-large sized shop has a ray of advanced machines available to spot all sort of things. Retina imaging and internal eye pressure to mention a few. Just my to cents. :)

That's pretty neat, I have been wearing glasses since I was 6 years old, and have never thought of it would be possible to buy a kit like this to verify and maybe even fine tune the prescription. I see on ebay they also sell adjustable trial frames that might fit your lenskit. Also what is so nice about this is that you can actually test the prescription a bit in different situations in stead of only the quick test at the optometrist

Very cool subject. I had no idea what goes into something like this.

Years ago, the magazine Electronic Design had an Electrical Engineer named Bob Pease write editorial style articles. Often times he would write about things unrelated to electronics. I remember one such article was about trying to get glasses from the optometrist that would be the proper prescription for night drving. His contention was that changes in light levels affected his pupils which in turn affected focus. I can't remember how or if he resolved the issue.

I was looking for random stuff and Matthias delivered again!

This was fun and interesting... I'd watch more.

Awesome video - thanks. Totally gonna try this...

I have a seldom-used physics degree, and I still use the U of Waterloo Optometry Clinic for my eye tests. Although asking for a thorough explanation from the student doing the test sort of puts them on the spot, it also challenges their depth of understanding. Though I usually avoid grilling the student when their supervisor is present; I don't want to put them too much in the hot seat! The other bonus is, because it is an optometry school, the eye test is quite extensive, much more than just measuring the prescription, and has found interesting conditions in both myself (traction (adhesion) between the retina and the vitreous humor), and my wife (protruding optic nerves leading to a partially-blocked cranial vein).

Rick Moranis - I finally figured out who u remind me of. 😂

I also have my own test kit. If you have mild nearsightedness, there's also tricks you can do without a kit. For getting sphere by measuring distance to blur in meters and inverting. So 1/2 meter of clear vision is -2 diopter sphere. For astigmatism, repeat the test looking through a slit. The angle of slit that gives you the best vision is your axis, the difference between your vision at that angle and 90 degrees from there is cylinder power. All that said, if you're nearsighted, you're at increased risk for other eye issues, get a doc to look at your retinas regularly even if you don't need him to order glasses.

At my last optometrist visit the usual machine (Phoropter) was fogging up. The optometrist just pulled out that set and figure out my prescription manually. His set was easily 2 to 3 times that size. He didn't have to stack lenses other than to try adding .25 or .5. I honestly preferred doing that than using the Phoropter. He let me adjust the dial for the angle myself. I liked doing that myself as well. It was easy to fine tune it for perfect clarity. After figuring my prescription out he let me walk around for a minute with the glasses on to make sure I liked the prescription. Of course since he already knew my old prescription it was a very quick process.

That was sooo cool. I have been needing a new prescription and your demonstration has just convinced me to get one of these sets. I would love to see a more in depth version.

Please do more on this subject. I hate going to the optometrist and not understanding wtf they are doing. Ive googled a bit to understand cyl is for astigmatism. Sph for the other thing, focusing far or close, but that is the extent of my understanding. Your explanation of how to check your prescription is great. Going to watch a few more times to fully understand it more. Thanks

This is why you are my favorite wood working channel :)

This is great. Would like to see you as Dr and Rachel or kids as patients with you saying better 1 or 2. 3 or 4…

Next week DIY Root canal : )

I would have had better chance to guess the 6/47 twice in a row than guessing the topic of this video. Amazing, I love it!

Love it when you dive into stuff like this, super interesting!

Well now I know I'll watch anything you post.

Good video. I like these "off topic/theme" videos every so often from your channel. It gives the sense you are letting us in on other aspects of your life and interests. For me, the appeal of this video was the DIY aspect more than the subject of optometry itself. In other words, I find the most interesting part to be seeing how you or someone else goes about resolving issues that people used to have to depend upon others for but, due to advances in technology and dropping costs of manufacturing, the average Joe or Jane can do for themselves with a reasonably similar outcome to "the professionals." Take care and God bless.

I'm disappointed you didn't grind and polish your own lenses

I found it interesting and would watch another video or two on this subject of optics

Really an interesting video and walkthrough of some of the basics. Although I'm fortunate so far in not needing glasses, everyone else in my family does, so I image at some point I may need some at least for reading. Definitely would appreciate seeing more on this topic!

I think this is the funniest video you've posted. Well done!

Interesting is good. Also you have the time to explain what is happening mechanically, something the optometrist doesn't always have time to do.

I remember seeing a model for testing if safety glasses will distort your vision. The test was a dummy head with laser pointers in the eyes that focus on a target at some distance. You can then place the safety glasses on the head and see if the glasses shift the point of focus. The shifted focal point leads to eye strain.

Brilliant, I've swapped lenses from broken frames to smaller frames by re shaping the perimeter of the lens before now (carefully preserving the orientation and spacing of the lenses, but this is next level. Those try-out frames suit you by the way :)

very interesting ! I hope you'll make more videos on the subject !

I've always wondered about this, I've always felt like I could do better if I was able to pick and adjust the trial lens changes myself as the operator seems to be rushing or pushing to get to their next scheduled client I also end up feeling pressured to hurry

Awesome video and very interesting thanks

You've almost got on the ASMR scene. Nice work

It's always a pleasure watch your videos!

Never fails to disappoint. Thanks for the knowledge

Great video, please do more videos like these.

Matthias, I have the same problem with the caliper (or other small stuff in the shop), and my approach was to buy a cheap head magnifying glass, with two sets of lenses plus one "super lens". Then I keep it in my head when working with small stuff and lower it whenever needed.

Very random video. But this channel is random stuff after all. I liked this video a lot. Very interesting topic

Very interesting video, and it sure does fit the title of the channel. Can't get much more random than testing your eye prescription

When you said "This video is getting long." I was surprised that 11 mins had gone by. It seemed more like 3. Very interesting video!!

Matthias, this was really interesting, it seems like there is a lot of support in the other comments for more optometry videos, please make them!

Trial lens refraction which is what Mathias managed to do for his own eyes came close to the accuracy of his own simple Rx, but as he points out there are many errors that can occur. As an engineer he must realize that he did not control other variables. Light levels, vertex distance, interpupillary distance, eye chart calibration, corrected curve lens design and additivity, eye muscle alignment, age, eye health, observational skills all must factor in to the accuracy of an eyeglass Rx. As a retired optometrist I refracted myself and was aware of these variables. Using state of the art test technology I still found that my quarter diopter subjective comparisons were not perfectly consistent. Human eyes and brains are not machines so it helps to understand and control as many variables as possible to optimize a spectacle Rx. Engineers are faced with the same issues of understanding and controlling as many varables as possible to optimize their projects.

You did great, the phoropter is obviously more efficient but much more costly and intricate. What you did was the extent of what most optometrists do as far as the refraction. You should look up the red green test as a help in finalizing that sphere power and how the different wavelengths of light are bent differently relative to one another

Would love to see more you have on this!

really neat! would love to see more

This is fascinating. I would love a video about the basics of how glasses/prescriptions/bad vision works in general.

Yes good stuff, make more.

That's pretty cool. I knew you could add diopters, but I didn't' realize you could stack thin lenses like that to add everything up. I like that you could put together a trial prescription like that and wear it around and look at different things to see if you got it right. I'm up to a -10 in one eye so I'd need a big kit to try it out myself.

unique topic, very nice explanations. now i understand this better

Fantastic video Matthias. I found it really interesting. I would certainly be interested in more videos on this topic. Seeing as I am also not an optometrist, I think it is easier for me to understand the subject when you approach the explanations as you would an engineering topic. -- It is essentially engineering anyway, most things are. I would also love to see if you can produce a more functional set of trial frames out of wood and wire. I did start messing around in CAD to see if I could come up with something functional and easy enough to build. I'll give it an hour or two more and if my creation is halfway convincing I will send it over to you, perhaps you could use it as inspiration for your own (doubtless better) pair.

This was quite different and also extremely interesting. I am curious now how it compares to something like EyeQue. I used their at home tester to get my prescription and was pretty impressed with the results. I think it uses prisms or something to do alignment in a circle. I'm not sure how it compares to traditional eye exams.