The most reliable, and ultimately decisive tool used at the optometrist, is a test lens kit and eye chart. Sure, there is the autorefractor and various other options but ultimately you always end up in front of test lenses, and an eye chart.
We talk about measurements a lot, here, and I offer a number of tools to measure myopia for yourself. These options are as good or better than what you get at the optic shop, for a number of reasons we frequently discuss here in the blog, as well as the full course.
Let’s clarify one thing, first. A test lens kit, is a test lens kit. At a nice optic shop office, you might see one of these:
While it looks imposing, it’s just an enclosure for test lenses. It makes measuring quick and convenient for a place that will see many customers every day. In principle and practice however, above contraption is exactly the same as one of these:
Instead of dials setting the lens in front of your eyes in the first version, this latter one has you inserting lenses, one by one, into the frame. It’s a bit more effort than turning a dial, but the way it works is exactly, 100% the same.
You don’t need a test lens kit. The links in the first paragraph take you to the centimeter calculator and printable diopter tape. Both of those work fine to give you an idea of your myopia degree. That and via the forum you can ask me what you want to get for prescriptions. It works well enough and is the most immediate and cheapest option.
However, if you really want to keep track and enjoy the process of analytically tracking results, you want a test lens kit.
You don’t need the expensive gear from the optic shop. You can buy a test lens kit, complete, for around 90 Euro (120 USD), from various online sources, like this one.
With that kit, you can emulate exactly the experience you would get at an optic shop.
It also helps answer the question of how much prescription for close-up and distance are exactly ideal for you, at any given time. And while the guess work is manageable the way we do things without the trial lenses, if you are serious about vision improvement, the investment may be worth it anyway.
How It Works
The lens kit includes lenses in 0.25 diopter increments. At the optic shop, they would use the autorefractor to get a baseline of how much prescription you might need. They will use those values to start out which lenses to dial in when you look at the eye chart.
Instead of the autorefractor, we use the printable diopter tape, or just any centimeter measuring tape and the online calculator. We use the diopter numbers you get from either of those, to pick the first test lenses.
You then simply insert the test lenses into the frame, put the whole contraptions on like a regular pair of glasses, and then look at your eye chart, affixed on an appropriate wall. Now, just as the optometrist would, you determine which lines of the chart you can see clearly. Not strong enough? Exchange the lenses for another 0.25 increase. Rinse, repeat.
Prescriptions are a simple question: How many diopters do you need to see the 20/20 line clearly?
And of course if you are working to improve your vision, you will want to figure your close-up prescription, which means using the test lenses to see if you get a good blur distance while using your computer or reading. As a starting point you might subtract 1.5 diopters from your distance prescription, and use the resulting values to load your test kit.
Once you have the kit in hand, it’s really very easy to do. It also adds to initial confidence when you have the whole set of tools available to measure for yourself, as well as track your progress with a full set of lenses.
Likewise you can also shop on eBay or any of the many other online outlets for sets that may most appeal to you. There are sometimes fantastic vintage sets available that are gorgeous collector items. There are high end German made options, and inexpensive Chinese alternatives. Around 100 USD / Euro will get you what you need, and beyond that you might indulge to your own preference.
Gorgeous. You might find one of these on Etsy.com if you are quite fortunate!