This, a pro topic.  

Quite a bit of the first month of BackTo20/20 is about starting to get a feel for blur.  Blur and clear vision, and the area in-between.  Getting a feel for how that space between clear and blur isn’t set in stone, how you can move that space either passively closer to you (by lots of close-up eye strain) or farther using focal challenge activities.

That’s key for a number of reasons, not the least of which to give you back the confidence that your eyes are indeed yours and not something to hand over to optometry to ‘deal with’.  

And of course the idea is that one you realize that you can affect how close that blur wall is to you, you’ll want to move it.  The more room you get to see clearly, the more you’ll want.  It’s easy to do with good routines and habits, and almost all students respond well to this approach.

But then as we dig deeper, we learn that there isn’t just one kind of blur in that blur wall.

There’s astigmatic blur, which you may already know about.  And there’s blur that’s mainly caused by your focusing muscle (the ciliary) not relaxing properly, after an extended close-up viewing session.  And there’s the blur that is ‘fixed’, based on your eyeball being elongated and light not focusing properly on your retina.


Astigmatic blur is *directional*.

Knowing which is which is very helpful in assessing your current vision, what kind of correction you may want to use, and how your habits are promoting good eyesight.

Let’s talk about ciliary vs. axial blur, for a moment.

Ciliary Blur

This will likely only make sense if you already spent time measuring your centimeter, if you already mastered active focus, and aren’t wearing full minus (all the time, at least).

Ciliary blur feels like a bit of a moving target blur in your distance vision.  You blink and things are clear, and you blink again and things are more blurry.  There’s a bit of double vision (another kind of blur we talk about) in your vision, that sometimes clears up (independently from blinking), and other times doggedly persists.  It’s kind of a mess when you break it down, really, ciliary blur.  

You will get a good feel for ciliary blur if you establish good habits and start mentally keeping track of your vision.


Starting a screen eventually causes your focusing muscle to ‘lock up’.

You’ll notice that after a weekend of camping, or a soccer session, or a day bird watching (I’m reaching here, whatever you might do to get away from screens), that ciliary blur mess is at a much lower amplitude.  Sure there’s a little double vision, a little clear and blur between blinks, at the edge of your diopter bubble.  But for the most part your vision feels stable and the blur horizon is consistent.  

Contrast this with your distance vision after eight hours in front of a computer, and ciliary blur will be very easy to understand.  For one blur starts much closer now, and the difference between blinks is noticeable, and double vision is annoying.

The important thing about ciliary blur is that you can (and should!) clear it up, every day.  

Moving on.

Axial Elongation Blur

This one is easy.  You take off your glasses (reduced diopter or otherwise), and you are hit by a wall of blur.

It’s static, simple, blur.

No matter how much you stare at it, or blink, it’s just a wall of .. blur.  There’s no nuance there, no moments of clearing, no distinction between astigmatic and double vision and opportunity for focal challenge.  

It’s just straight, looming, unquestionable, blur.


Axial elongation.  Light converges before the retina.

This kind of blur is going to slowly, very slowly move further away, as you work on keeping ciliary blur low, and challenge your eyesight, every day (remember, axial change goes both ways).  You can tell how you are doing by using an eye chart, to figure out the battlegrounds and your progress getting your eye back into pre-glasses shape.

All this, just words serving less then ideally to vaguely describe a visual experience.  

You have to start measuring, stop wearing full minus, to be able to relate and form your own meaningful experience with blur.  Once you understand the different types of blur from personal experience, you can quantify how your actions affect your eyesight – and make choices on what you might want to do with this knowledge.  ;)