Learning How to Read an Eyeglass Prescription then Order Glasses Online

December 8, 2022

Background

I had new progressive glasses prescribed in February 2022.

This prescription was MUCH stronger than previous prescriptions prompting the technician to question the Optometrist, just to make sure he did not mess up.

He did not, but, the technician told me to let her know if I experienced any issues……and to expect at least 2 weeks to get used to the glasses. (It takes time for the brain and eyes to coordinate what they are seeing…..I did not know that!)

Everything was fine…..for 8 months.

Then……I experienced a “wobble” when getting up to walk, similar to getting used to new glasses, so I went back to my old, 2020, progressive glasses to see if the wobble stopped.

It mostly did, but not completely.

I waited a little over two weeks to see if the wobble stopped, and it was pretty much gone, at which time I embarked on a quick STUDY of optometry, focusing on how to read the prescription, and understanding the differences between PROGRESSIVES and LINED BIFOCALS.

Reading the Prescription

Let’s look at the prescriptions first, as a basic understanding of the rest of this blog kinda requires it…..

My prescription looks as follows (I only show the fields that had numbers in them):

	Sphere	Cylinder	Axis	Add
OD (Right Eye)	+1.25	-1.50	97	+2.50
OS (Left Eye)	+4.00	-4.75	138	+2.50

Looking at the Chart

The plus values (+1.25 and +4.00) in the Sphere column show that I am farsighted. A minus value would indicate that you are nearsighted.

I have an astigmatism in both eyes depicted by the numbers in the Cylinder (the severity of astigmatism) and Axis (which shows the angle of the astigmatism). As you can see, the left eye is much worse than the right. And…..to make matters worse…..I have age related cataracts in the left eye. Arrrghhh….

The magnification for the reading part of the bifocal is the number under the Add column: +2.50.

That number (+2.50) determines, not only the magnification for reading but also the distance from your eyes where reading is in focus: The focal point.

The focal point is based on the following formula:

f = 1/D (are you now sorry you blew off Algebra? haha)

Where f = focal point in meters (the distance from your eyes where the image is clear) and D = the Add number in diopters (in my case both eyes = +2.50).

Doing the calculation….my focal distance according to the prescription should be = .4 meters which is 40 cm (move the dot over 2 spaces) and at 2.54 cm / inch = 15.74 inches.

Great for a book, but, my Pixelbook Go screen is further away than that. In fact, using the bifocals based on the prescription…..I have to get abnormally close to the screen to see it clearly.

Thus the need for computer glasses. 🙂

Computer Glasses

If I ordered “computer” glasses and used a D value of 2.00 (rather than 2.50), I calculate that my new computer glasses will allow me to see my chromebook screen clearly as long as it is about 20 inches away. That extra 4.25 inches of focus length will help a lot.

In theory. 🙂

Progressives vs Lined Bifocals

Progressive lenses not only have the two main focus modes, near and distance, but it also has a whole bunch of focus points in-between.

Although that comes in handy for focusing on just about anything at any distance……it makes it hard to find (at least for me) the focus I need, and when I do, for example for reading, it is a VERY narrow field of focus not even covering a few words in a paperback book (I read A LOT and the focus width is VERY important). As it is (with the progressives)……I have to move my head….constantly….as I read.

I made a preliminary decision that I might benefit from simple LINED bifocals where I would have only two focus modes…..distance or near.

And for reading, I will (in theory) have a wider field of view so I could see the whole page in a book clearly by just moving my eyes. (NOTE: it turned out to be true…..the whole damn book, both open pages, is now in focus!!!!)

To complete testing of my theory (that lined bifocals might be better for me)……I went online to order simple BIFOCALS (with a line) to test in place of the progressives:

Zenni.com

Ordering the Frames and Lined Bifocals on Zenni

Going to the Zenni Optical web site (mainly because of 49er George Kittle’s endorsement), I picked out a cool frame (for me!), and then set out to order the lenses….

The first thing I had to do was enter the distance between my pupils known as the PD measurement! And, as luck may have it, that number was NOT on my prescription! I suspect I know why……but, Arrrghhh…..just the same. 😉

Long story short, after watching a video, I think it was on Zenni, I made a business card with dots every 1/8th inch on it, held it up to my forehead, and took a picture with my Pixelbook Go.

I then put the picture of me and the business card in Google Drawings and drew two vertical lines from my pupils to the 1/8th inch dots. Figuring out the millimeters between them, I came out with a PD of 60.

The rest of the form was easy since I had all the numbers I needed from the prescription. The only question I had was the ADD of +2.50 but it turns out that that number shows the eyeglass maker that the glasses will be a bifocal (aka old person) with a near view magnification of +2.50 diopters!

In the picture above, the sections of glass below the horizontal lines are the +2.50 near view sections. So I look down (with only my eyes) to read and everything is CRYSTAL clear…..and enlarged!

Cool.

Quality and Cost

Oh, as an added benefit, the glasses from Zenni (yes, I was surprised) are as close to PERFECT as you can get. Far better quality than the glasses I got from my Optometrist…..

……AND……$98.00 vs $201.00 !!!

Sooooooooo, I bought computer glasses, for $102.00 from Zenni too!

For single vision computer glasses, I added the +2.00 ADD (as discussed above) into the SPHERE value (so I can be 20 inches or so from my Pixelbook) on my prescription above: Now my single vision, computer glasses, Sphere is: +3.25 OD, and +6.00 OS while the Cylinder and Axis stay the same.

As for cost…..TWO Zenni glasses $102.00 + $98 = $200……which is still cheaper than ONE pair of glasses from the Optometrist.

My new, really cool, Zenni computer glasses….and Grogu. 🙂

I now have 2 glasses for the price of one…..and…..MUCH better quality!

UPDATE Dec 24, 2022: To complete my testing (and since the glasses are so cheap)…..I also ordered premium progressives from Zenni ($150.00) to see how they work. Supposedly these will have wider field of focus ranges than ordinary progressives…..I’ll let you know how they are in a couple of weeks. 🙂

A Few Weeks Later…..

Progressive glasses win the testing!

The ability to see at virtually any distance and stay in focus make progressive’s the way to go even though getting the old brain used to them was (and still is) quite difficult (age? stronger prescription that actually took into acount my astigmatism?)

Quick story…..A visit to ACE hardware cruising the aisles proved that progressives were needed as with the lined bifocals NOTHING was in focus (either too far for the close, or too near for the far). 🙂

Thanks to the ACE trip, and the realization that progressives are the bomb…..my old brain finally got used to them, and…the rest is history.

Moving forward to 2024 and beyond……using Zenni.com………I can buy TWO glasses: Premium Progressives AND Computer for the price of one somewhat crappy pair from the optometrist.

Latest Update October 2023

I ordered a pair of George Kittle sponsored glasses (Sunny and 85) from Zenni and they arrived October 5, 2023.

After all the testing above, I knew that a medium frame fits my face the best and that I preferred larger lenses (these are 43 mm high and 52 mm wide) in my premium Zenni progressives.

The instant I put the Kittle’s on….I actually said out loud:

WOW!

They are perfect!

Conclusion

This has been fun as I learned a bit about optometry in the process……

Geek on!

More GEEK stuff…..