Hey [s2Get user_field=”first_name” /]. You’re back! Nice. 🙂
Let’s get into a bit more eyesight measuring concepts today.
To fully appreciate and track your vision improvement progress, we have three principal tools available (plus one big bonus option).
You want to use all three (or four) of these tools to monitor your progress. Later on we will discuss additional strategies as they become relevant.
We need to distinguish between relative and absolute numbers when it comes to this.
One, we have the numbers you use to measure refractive error (for absolute numbers). Principally, this is the centimeter measurement (also our #1 tool). Then, for relative measurement, you have the Snellen test (number two tool). Third, we use a distant-object-test, some writing ideally, as a reference (number three tool). Number four gives us a lot of extra potential data, and is also an absolute measurement.
The centimeter measurement is highly useful to help us determine normalized prescription, and give us an idea about strain (as previously discussed). You take a few centimeter measurements beginning and end of day, you can quickly tell how much your eyes were affected by your day’s activity. But then there is a problem with using only the centimeter:
While it gives you a refractive error reference, and a way to translate blur into diopters, it doesn’t give you very good feedback of your actual distance vision.
Why is that? There is the process of accommodation, your eyes changing focus. Just because you see clearly at x-centimeter up close, does not translate 100% accurately into distance vision. Still, centimeter is valuable on two fronts – giving you refractive error, and also variance (strain measurement). But then when you want to answer the question of ‘am I getting better’ in small increments, the centimeter lets you down.
The centimeter is a great tool, but not right for every question. Let’s consider a very common scenario:
You have been participating for several months, you had your second normalized prescription change, your vision has improved quite a bit. But now you are hitting what feels like a plateau. Your centimeter measurements are consistent. You second guess the edge of blur, wanting to get another few milimeters more distance. It’s just not happening. You feel like you just can’t see that clearly, everything is just … stuck. Most clients end up in this place sooner or later. In a common -4.00 scenario, this is often around 3-6 months in.
So, what do we do?
The Relative Snellen
This is where you have the relative Snellen and the distant-object-test to give you the feedback you are looking for. The relative Snellen is a decent tool for this – you can use your normalized prescription to check whether you can read another line on the chart. You can step closer, without lenses, and see if your distance to the Snellen has changed (where you can still see it).
I like this test, because it involves another dimension – a longer distance than the centimeter measurement, and it gives you two reference points:
Feedback #1 – Impact of your normalized prescription on your distance vision
Feedback #2 – Relative distance vision, uncorrected (or with differential)
It’s a good thing to do every once in a while, and keep a log of. Once a month is a good interval, with a few measurements (ie. the last three days of the month, take the average values, record in the log). Do both uncorrected and log your distance to the chart, and corrected and log your ability to see the letters.
There we have a way to test and get two points of data. Another good reference point. On to #3, one of my favorites:
Distant Object Test
We already discussed this one: You focus on some writing in the distance, using your normalized prescription. This is some writing that you can only read when you make an effort. Street signs are ideal for this, where the writing is less than 20cm tall (your mileage may vary, depending on the degree of your myopia / refractive error).
Why reading? It’s a bit more accurate than just an object. It needs to pass the “can I actually read this” test.
It’s also ideal because it represents real world conditions. Outdoor lighting, it’s not an abstraction of distance (like the centimeter), your eyes do what they are supposed to – provide data about a distant object.
So when you wonder if you are making improvements, I always, always suggest this: go outside, find your reference object, blink, squint, do left eye closed, right eye closed, use all your tricks to bring it into focus. How are you doing? Compared to last month? You might realize that you improved here, more than you do with centimeter and Snellen. It’s quite common in fact that you see improvement here before you notice it with the other two measurement tools.
I recommend to do this along with your standard focus-puling exercise, and KEEP A LOG. Remember, this project is about habits. Being able to pat yourself on the back once in a while, seeing that you are actually continuing to improve, is entirely necessary to maintain progress. Motivation, we must respect it’s role in our vision improvement project.
This leaves one more way to test. If you have been in one-on-one for more than a few months (and more than -2.00 refractive error), you likely own one of these already:
The Test Lens Kit
I don’t bring this one up early on, because it tends to be overkill, and I want you to learn the other measurement tools first.
Basically you are getting a case full of lenses and a frame created to insert different lenses. You can try out various prescription strengths, and see exactly how much they affect your eyesight. With them, you can measure for myopia, hyperopia, astigmatism and presbyopia. Handy!
You may want to consider one. Mostly if you are high myopia, at least about -3.00, and / or have astigmatism of -1.50 or more. It’s not necessary to have one, and you won’t suffer in any way by skipping the test lens kit. It’s a $200 investment (in most 1st world countries), which is optional. What’s the upside?
Feedback #1 – Refractive error confirmation – you put on the lens, experience vision corrected
Feedback #2 – Astigmatism error measurement – the only good home way to do it
If you are not in one-on-one and aren’t sure about a test lens kit, post in the forum. I’ll be glad to share additional advice, and some of the one-on-one participants may add their own experiences and thoughts.
What do you do with all this information?
1. Add a little habit of doing centimeter, relative Snellen, and distant-object-test to your routines
2. Put a perpetual, once a month reminder in your calendar: create log entries of measurements
3. If you have high myopia, consider a test lens kit
Questions? Comments? Drop a line in the forum.
And yes. Total distance for the day. I keep saying it’s coming up, and it is. Hopefully you are tallying your daily distance time.