The Measuring Tape

Once you have a bit of practice, taking a centimeter measurement only takes a few seconds.  You will use this for several purposes:

  • Get a baseline reading before you begin your improvement journey.
  • Measure for variance – How much your eyesight changes throughout a regular day.
  • Measure for strain – How much your eyesight is affected by long hours in front of a computer.
  • Measure for prescription – How strong your glasses should be.

That is a lot of information to get out of a single measurement!

Once you begin charting results, you will gain a much better understanding of the non-static functioning of your eyes.

Your vision might be as much as 20-40% better at it’s best, vs. its worst – and that could be in a single day!

You will also find out that the once-a-year measurement you get at the optometrist office is just a random snapshot in what is a potentially wide range of readings.  

When you go to the optometrist, they put you in a dark room, with a single bright focus area.  They use the bright focus area to check your vision, using several possible tools.  

A dark room, as you can test for yourself with the centimeter, is actually one of the worst ways to measure your vision.  You will see a lot LESS in most cases, if your peripheral vision is blocked (in this case by the lack of light).  Based on that measurement, you may have gotten one of several rounds of over prescriptions, which further degraded your vision.

So, by learning the centimeter measurement, you will be able to avoid potential over prescriptions, and protect your eyesight.

If you do nothing more than learn this measurement tool, and check your own eyesight, you are already taking a significant step towards protecting your eyesight – being able to reference check the values you are getting at the optometrist’s office.

For this Part I of the Centimeter Measurement, let’s see what you will need:

  • 1. A small tape measure.
  • 2. Text – could be a printed page or computer screen.

Really, this makes measurement incredibly simple – because you need nothing else than a tape measure, and any reference text for your eyes to focus on.  People often wonder how this can be as accurate as the thousands-of-dollars auto refracto meter.  Just remember:

The myopia diopter value is just a measurement of how for you can see before things get blurry.

Here’s how to measure:

Sit in front of the computer (or a book), without glasses.  Do this before you start using glasses, in the morning.  Start up close and slowly move back until the text starts to look blurry.  You want to catch the ‘edge’, where things are still sharp, but just so.  Another small move backwards, and things are starting to blur.  Make sense?  You want the distance where you can still see clearly!

The ‘edge’ is key, because that is where your eye is basically ‘all the way back’ at it’s ability to focus.  If you stay closer, there is still room in your eye for more focus.  If you stay too far back, your eye is already past it’s range of focus.  You want that point where your eye reaches that end of being able to focus, and things get just a tiny bit blurry.

This is a bit subjective, but will give you a very workable reference point.

Once you found that distance where things are just barely still in focus, grab the tape measure.  Roll out enough tape to cover the distance, with some room to spare.  With your left thumb, press the end of the tape to the screen (right at the 1 centimeter mark).  Then, with your other hand, place the other end of the tape next to your eye (the side of your head / eye socket).  That’s an easy way to exactly measure the distance between your eye and the screen.

What’s the best tape measure to use?  See the end of this post for my recommendation.

And that’s it, the centimeter distance you can see clearly, from screen to your eye.

Next, we want to translate this number into what optometrists use – the diopter.  When you order glasses, that is the number you provide to tell the strength of the glasses needed (how much focal plane change is needed to see clearly, at a longer distance).