If we are going to keep it at its simplest possible, a diopter is an expression of inverse meters.

Or, how many meters can you see clearly – before the image becomes blurry. If you have perfect healthy eyesight, there is no limit to that. Things just get progressively smaller and smaller, but never blurry. If you have myopia, that’s not the case – then there is a point where after so many meters, there is blur.

All that the equipment at the optometrist is meant to determine, is how many meters you can see, before there is blur.

That’s it. And ironically, the fancier the equipment, the less accurate it is. I write about this in the blog, and joke about it every so often. After all, all your prescription says, is how many meters you can see before blur. That’s it. And what does it take, to make this determination?

Measure Your Eyesight

It’s so simple. For example, you might look at this page without glasses. If you take them off and get close to the screen, everything should be clear (unless you are very high myopia). Now you will move back slowly, until the text is no longer perfectly sharp. It’s the first bit of blur you are looking for. Once you get there, stop.

Now you need a measuring tape (I could have mentioned this earlier, couldn’t I), to determine the distance. We use centimeters here, since it’s easy and accurate. Let’s use the example where you have a -3.00 prescription (and let’s assume this is accurate for your current vision). You would be able to go back to 33cm from your screen, before there is any blur in the text. Since diopters (that -3.00 is three diopters) is just a way to say “inverse meters”, we could as easily say 33cm. Though that wouldn’t be as fancy and doctor-speak, and give away just how basic the concept is. Remember, this is 600 year old medical technology we are talking about.

And since I want to help make this easy, you don’t need to do any math either. The site has a link to the myopia calculator on the top of every page – once you determine how many centimeters of distance you can get, you just plug in the number. The calculator will tell you exactly how many diopters of correction you need, to address that amount of myopia.

So, What’s Next?

You need a measuring tape. Remember what I said – if you want improvement, you will have to get out of your chair a few times. The small flexible tape is the best, usually something you can buy at a crafts or fabric store – tailors like them a lot, and they cost less than 2 Euro / dollars. You can find them online, or locally. You will want one – if you actually get into working on improving your eyesight, you will be using it to keep track of your improvements. You will also see me mention centimeter a lot on the site, and others talk about it in the support forum.
This really is key – no centimeter measurement, no point in moving forward. It’s also quite fun to do, and it will tell you a great deal more about your eyesight, that I haven’t covered yet.

So get a tape, and measure your centimeter!

Oh, and one more thing … measure it more than once. Do it in the morning, before you spend time with close-up work. Do it again after hours at the computer. And do it again in the evening, in poor ambient lighting. Let’s see if the result will vary – if the optometrist is to be believed, they should be exactly the same at all times (but since they won’t be, that should be another nail in the coffin of credibility of those guys).

Next, we will look at what to do with those centimeter results. You’ll likely have questions, as you will probably find some curious things, when you do these measurements. Possible quite a few curious things, which hopefully will get you curious about what’s going on here. And fortunately, I have answers for you – which will actually help you, if you do the measurements. If you just read on without trying, this will be meaningless and academic.

For actual improvement, do participate!

See you tomorrow,