Making My Own Glasses

It’s a long weekend, I’m standing in my flat, 10 lenses scattered across the desk in front of me. I’m wearing weird glasses consisting of an empty plastic frame and some lenses stuck into it. I squint out of the window, trying to read number plates of cars parked in the street.

What happened?

It all started with the idea of getting my Pilot’s License for which you need to pass a medical exam which includes an eye test. Being a contact lens guy, I had a pair of glasses, the lenses of which had values that had gone out of sync with my contact lenses. I was only using it for staring at the screen in the evenings and didn’t care.

This however posed a problem for passing the medical exam as an eye doctor checks your eyes and your glasses. I therefore went on a mission to get new glasses. Getting new glasses is simple, right?

Getting new glasses is simple, right?

On a superficial level, getting a new pair of glasses seemed simple. But once you add in my perfectionism, it exploded in complexity. I ended up going to two different opticians and an eye doctor.

Optician 1

I enter the store. A very friendly lady wearing hipster clothes greets me. The equipment seems a bit minimalistic – only a small room with a chair and some letters on the wall. Not sure if all the five-star reviews on Google Maps were fake or submitted by other hipster people who don’t care much about equipment.

She measures the lenses of my old pair of glasses with a Lensmeter. Based on those values, she conducts the eye test. Unfortunately, I can’t find a pair of glasses which I like and she’s not happy to share the measurements with me as she fears I’ll run off and get my glasses made online (I’d never do that!).

She seems to forget the fact that I’m a doctor which means that I’m good at memorizing arbitrary facts and I also know some things about eyes. I catch a glimpse of her notes and remember the values.


R sphR cylR axL sphL cylL ax

Optician 2

I pondered the “I have a very specific taste and am not happy with most glasses” problem. This time, I prepared by looking at glasses online. I found a model which I liked.

At an optician store which was a partner of the online shop, I get another eye test done. The guy is super nice and he really seems to know his stuff. The equipment seems much more sophisticated, most notable he measures my eye values with an Autorefractor prior to conducting the eye test. He seems more confident in the way he holds lenses in front of me.


R sphR cylR axL sphL cylL ax

Wait, what? A difference of +0.5 in the left sphere and -0.75 in the left cylinder, also +18° in the left axis?

The difference in the sphere can be explained, he said I’m probably between -6.5 and -7.0 and he prefers to use the lesser strength, makes sense. The difference in cylinder is hard to explain though.

I end up ordering a pair of glasses from him directly, ditching the online store. For me, it actually made sense to pay the premium as his service was great.

Two weeks and three meetings later (long story omitted), I have my new glasses. They’re great.

Or are they?

I’m not sure. I do see much better than with my old glasses but I still see worse than with my contact lenses. Maybe the measurement wasn’t completely accurate?

Eye Doctor

As you might remember, I was actually in the process of getting my medical certificate for the Pilot’s License. For that, I had to get an exam by a certified eye doctor.

The nurse measured my new pair of glasses with a Lensmeter, entered the value into a Phoropter and let me stare at some letters.

Nurse: “Can you read those letters?”

O: “Yeah”

Nurse: “Please read them out loud”

O: “Umm wait.. No.”

Turns out, I couldn’t see all that well with my new glasses.

Talking to the eye doctor, I mentioned that these glasses were new and what he thinks of them as they apparently are suboptimal. He said something along the lines of “dude you’re so short-sighted, the variance in measurements is always going to be there and your optician did a good enough job”. Well, that at least confirms my positive opinion of the optician.

I asked him if he could share the measurements with me. As he wasn’t afraid of disruption through online opticians, he was happy to print them out. Note: These are the automated autorefractor results. The optician results so far were eye test results.


R sphR cylR axL sphL cylL ax

Wait, what?

Now there’s a cylinder of -1.0 in the right side (R cyl, R ax). Also, the difference in the left cylinder (L cyl) is -1.0 compared to Optician 2.

The Problem

My eye test problems can be summarized in one dialogue:

Optician: “Now with this lens, do you see better or worse?”

O: “Honestly, I have no clue. Maybe. Maybe not? The letters look similar but different.”

I have a few seconds to decide whether I see some letters better and this decision will decide which lenses I’ll have in my glasses for the next few years? Absurd!

How can a trustworthy decision be made in this not-real-life scenario of staring at letters on a wall? I want to be able to decide while going about my daily routine: Staring at computer screens, looking out of the window, looking into space. My daily routine doesn’t include staring at the same five letters projected onto a white wall and reading them out loud. When trying out contact lenses, that’s actually how it’s done: Your optician orders a new pair for you and you wear it for a few days. Only then you decide whether it’s an improvement.

But I want the same process for glasses. I am sure that I can determine whether a certain lens is an improvement (“do I see better or worse?”) if only I’m given enough time to try it out in my own settings.

One evening it dawned on me. “If only I had those lenses” I thought. Both problems could be solved – I could take my time trying them out in the comfort of my own home.

How expensive would that be?

Doing it myself

I needed an “optician kit” consisting of:

  • Trial lenses: A large number of lenses with varying corrections
  • Trial frame: A pair of glasses without lenses into which you can insert the trial lenses

Turns out, you can order these kits online from very trustworthy Chinese resellers for around 190€.

Fast-forward two weeks later. It’s a long weekend, I’m standing in my flat, 10 lenses scattered across the desk in front of me. I’m wearing the trial frame with some lenses stuck into it. I squint out of the window, trying to read number plates of cars parked in the street.

As a doctor I know some things about the human eye so I understand how to use those lenses. However, I have no clue about the magic ritual of the optician (“Do you see better with this lens?” – selects random lens and holds it in front of my eye).

Luckily, I didn’t have to. As I already had three results, I could try each of them out and then make minor changes through trial and error. Also, I had my pair of new glasses by now so I had a ground truth to compare the Chinese lenses to.

Initial findings

Before an eye test, the optician typically tells you to not wear your contact lenses for at least 12 hours. I wondered if there is any evidence to support this, so I conducted eye tests of myself in the evenings just after taking out my contact lenses and in the mornings 12 hours later.

Interestingly, there is a measurable difference of around -0.5dpt in the sphere and -1.0dpt in the cylinder. So it’s pretty cool that I could experimentally prove this.

Own measurement

After a some trial and error, I arrived at a combination of lenses with which I could see very well. Looking through the trial frame with the lenses in it, my vision was better than with my new pair of glasses and even better than with my contact lenses. This was the best I’ve seen in years and quite an experience in itself.

R sphR cylR axL sphL cylL ax

Compared to the optician who made my glasses, the values for the spheres are identical but the values for the cylinders on both sides differ by -0.5 and -0.75. Interestingly, I measured the same axis on the left side which is some evidence that I’m doing things correctly.

Compared to the eye doctor, the values for the spheres are identical again while the values for the cylinders differ by +0.5 on the left and +0.25 on the right side. The values for the axis are identical (right) and very similar (left).

When trying out lenses by yourself, there’s always the danger of over-correcting the sphere when being short-sighted. Here, this wasn’t the case as I measured the same sphere values.

So I arrived at some sort of juxtaposition of prior measurements. I can’t really explain how the prior eye tests could get some values right while getting others wrong.

So far though, my measurements were solely based on the Chinese lens kit. I still couldn’t rule out an error in the lenses or even my measuring skills. What if I was making a mistake?

Putting my money where my mouth is

The only way to put my measurements to the test was to order a pair of glasses with those values. Of course, I wanted to control for the frame so I’d have to order the same one.

With my values and a 20% discount code, it still would cost around 280€. Quite a sum for measurements based on cheap lenses and my total lack of experience.

I went through with it and the pair of glasses arrived around two weeks later. Putting them on for the first time, my vision was just as perfect as with the trial lenses. Awesome!

This was hands-down the best pair of glasses I ever had. Better yet, it was the first pair of glasses with which I could see better than with contact lenses (as those don’t have a cylinder).

Closing thoughts and cliffhanger

I was able to conduct a more accurate eye test and confirmed my measurements by ordering a pair of glasses which turned out to be my best glasses ever.

I feel like there’s quite some potential in optimizing your health if you dig deep and put enough time into the process. You want perfect lenses? Test your eyes repeatedly for a few hours in total. Want to optimize your medication? Read up on all relevant studies and guidelines. Want to optimize your blood sugar values? Get a continuous blood glucose monitor and keep track of everything you ate.

But why were the other eye test results inaccurate?

Maybe it depends more on the time you get to spend with the new lenses before having to make a decision? Or maybe the two opticians I visited were simply not good enough. Or my eye sight actually changed in between measurements.

I went back to the optician with the story that “an eye doctor has measured some slightly different values”. He became very interested and we did another eye test. He was blinded to the values which I had measured. Surprisingly, both the measurement with the refractometer and the eye test now yielded different results which were identical for one eye and very close for the other! So there is some evidence that my eye sight may have changed in the meantime and the optician actually did a good job. We decided to follow up on this by doing another eye test in the near future, stay tuned.

One more thing. Do you remember the process in which an optician makes you wear a new pair of glasses and stares at you with this optician-look, takes the pair of glasses away from you again, goes to the back office and starts bending parts of it in a seemingly random manner, comes back, hands you the pair of glasses which now suddenly fit perfectly?

Yeah, I attempted to do that with my new pair of glasses and noticed that I suck at it. I would bend it to look similar like the glasses from the optician only to realize that the back of my ears were hurting after a few hours of wear. Then I would bend them differently only to have them repeatedly slip forward on my nose warranting me to push them up every few minutes.

After two weeks of bending, it still fits less well than the other pair. So I guess there are some subtleties of making glasses which are not easily replaceable through an online store.

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