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Why Does Your Prescription Change So Often?

Last Reviewed: January 2, 2020

Good question!

If glasses improved your eyesight your prescription should get lower over time, right?

Then it'd make sense. You'd just get weaker and weaker glasses until they are gone... but when did that ever happen to you..? Exactly!
So, why do they get stronger over time?

Because optometrists regularly overprescribe... meaning you get glasses that are too strong. That's why you get the headaches with new glasses for 2 or 3 days...

Your eyes just get used to the too strong glasses...
So, why do you get glasses that are too strong?

What most people fail to realize is that your eyesight is dynamic. It changes constantly throughout the day!

You may have -2 (or +2, or a certain IOP, whatever... it all comes down to the same thing) in the morning. Then mid-morning have a really strong coffee with a lot of sugar and milk...

So for 30 minutes your eyesight will be great. It'll be sharp. You'll feel great. You'll see crystal clear... so it'd be around -1 (+1, etc...)

Then the sugar crash sets in... the caffeine wears off... and slowly your eyesight gets worse again...

Back to -2... and then the liver has to deal with the sugar and milk... meaning, your eyes get less energy than they should... and now you are down to -3!

(The numbers are arbitrary examples to illustrate the point. The same fluctuation happens with plus-glasses, eye pressure, astigmatism, eyestrain, floaters, etc)

So, if you come to your eye test after the sugar crash, you'd get way too strong glasses this time around!
There are many factors that influence your test:

  • anxiety during the test (that you could get stronger glasses... the self-fulfilling prophecy)
  • what you ate
  • the eye drops making you nervous
  • you feel pressure to get the test right
  • a shitty night... lol
  • fight with your spouse /boss/friend/coworker
  • stress

... etc

There are so many factors... I think you get the point!
The Science

A study was done with 20,000 school kids... they tested their eyesight multiple times throughout the day... and what they discovered is amazing:

  1. all kids had perfect vision for some time throughout the day
  2. NO child had perfect vision all day long!

But every child was different... because every person is different!

You react to bread and bananas differently than I do... your digestive systems behaves differently than mine... depending on that, the test will change!

You and I cope with stress differently... so both of us can get affected during the eye test depending on our make-up...

It's not that you are right and I am wrong... or the other way around... but what IS wrong, is to judge the strength of your glasses on a momentary picture of your day...

Coupled with a totally unnaturally scenario to test your eyes...

Come one, you never drop stuff in your eyes to make the blurry... then look with one eye at a time into total darkness... to read letters of a font-size smaller than the smallest size available on your computer...

You never use your eyes like that in real life! Ever...

And that's why your prescription changes so often...

The most accurate measurement would be to test your eyes with a 20/20 vision test in daylight throughout the day multiple times... take the average, and there you go!

That would be the closest to an honest evaluation.

But your prescription would stay pretty consistent... and you wouldn't buy as many glasses... so the test machines make really good money for the "experts"...

The thing is...
You Can Turn This Around!

With the right system, you can reduce your strength and get weaker and weaker glasses... until your glasses are gone!

It's not fantasy, it's what we help our clients do each and every day... it's the Pure Vision Method™...

If you have an eye test anytime soon, do this:

  • eat very light and healthy (salads and light snacks) all day before the test
  • drink loads of high-quality spring water from a glass bottle
  • have a strong coffee just before the test starts 😉

=> that way they won't overprescribe you... 🙂

Stay tuned for tomorrow's bag of tricks!

How did you like today's lesson? Was it useful?

Just leave a comment, give me feedback, and let me know what your questions are!


Professionally Reviewed by
Mark Bushby

1 Comment

  1. Sharada on October 23, 2016 at 9:28 pm

    I am definitely going to try it..
    Dr. Said I have a high myopia and my left eye is weaker than the right one but prescribed a point or two low for left eye and somewhat higher for the right eye..
    I was and still having difficulty with these powers of the contact lenses…I wear specs too but that has low power from the contact lens but I feel comfortable with specs although it has less power and I see blurred texts sometimes (mostly because I wear it somewhat low on my nose) ..
    I don’t know how to be comfort my eyes..

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