Determining diopters for 20/40 vision

I am just starting out in trying to improve my vision.

After measuring my eyesight over the course of a week I came up with an average of R -5, L -5.50

So I guess I got a little too enthusiastic about this and jumped into ordering new glasses too soon!

The glasses I ordered are R -5, L -5.50, to match the measurements I came up with. I simply disregarded the astigmatism part of the rx which may have been a big mistake?

This is my actual RX:
OD -7, cylinder -0.50, axis 165
OS -7.50, cylinder -0.25, axis 160

Apparently the strength of the new glasses I just got is way too much too soon.

Testing out my new glasses using a Snellen chart, I can only really make out the E on the 20/220 line! Even that is blurry! - but it is the only letter on the eye chart where I can perceive the different parts of the letter.

My understanding is that ideally I would want glasses that allow me to read down to the 20/40 line, so that I still have good distance vision with just some blur on the edge - but I have no idea how I would determine what strength that is, without a collection of different strength lenses to try on and test.

Should I send these lenses back and get different strength lenses and if so can anyone offer any guidance on how I can get a better idea of the right strength? It would be much appreciated! Thanks.

How do things look on your computer screen with those new glasses? They are 2 diopters lower than your habitual glasses. 1.50 is a common reduction for near work. You could try these for a month for computer work and reevaluate. If they are too weak for computer work you can save them for your next differentials (near glasses) and get some stronger ones for now.

Or 20/30 or even 20/25. You have to figure out how much blur you need to get a good challenge, but just a little.

Computer work is a good place to test how you do with that cylinder elimination. See if you have “directional blur”. See how far you can sit away from the computer with those new glasses before it looks blurry. Can you work right around there?

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Thanks for your reply Shaerah.

I am using a large screen tv for my computer monitor with a pretty large font size to make text easier for me to read. I am about 28 inches from the screen. What I have found is that with all windows open and light coming into the room, I can read the text but it doesn’t look quite right. I wouldn’t call it blurry. I don’t know how to explain, it looks kind of faint, like the letters are not solid. I’m wondering if this might be the effect of the astigmatism? Is this a good point from which to be reading to challenge my eyes? I do have the impression my sight is being challenged, yet can still read without much strain.

If I move back even further to the point where I would say there is real “blur” - at that point I either can’t read the text or really have to strain to do so.

So far I have not seen anyone mention these different stages where from a nearer distance letters first appear faint and less solid, then moving further away, actually become blurry. I’m wondering if the first stage where letters seem “faint” is an effect of astigmatism. At any rate, it makes it a little hard for me to judge exactly where blur begins when I am reading, because I’m not sure if that first stage is actually “blur” or not!

I noticed with less light in the room, text on my screen becomes harder to read from the same distance. But I also did an experiment and did some distance viewing of the landscape outside the window for 20 minutes, and when I came back, all the text was clear to my eyes, from the same distance. This really surprised me. I’m wondering if it was some freak thing, or just 20 minutes of distance vision really enabled me to read the text more clearly. I’m going to have to try that a few more times to see.

Another thing I noticed is that using these new glasses for closeup reading, like books, or phone, my vision is crystal clear. That is very nice - I know I have needed reading glasses for awhile. But of course that isn’t giving me any visual challenge. Should I be using no glasses at all when I do something like read a book or look at my phone? The only problem there is I’m so near-sighted right now I need to hold the book really really close to read - so close it’s a bit uncomfortable.

From what you say I gather I should only increase my diopters a minimal amount for my main glasses. After reading a few more threads in the forum I have seen some people recommending -.25 or -.50 increments.

Right now even with my older glasses which are R -7 L -7 (plus astigmatism adjustment) I can only clearly read down to the 20/25 line.

What if I were to go for the most minimal increase for my next glasses? Going from my current rx of R -7.00 L -7.50 to R -6.75 L -7.25 and keeping the cylinder variables the same? Do you think that would still give me enough challenge, or would it be better to increase by .50 and keep cylinder the same?

I should mention I never filled my rx for glasses with the -7.00 -7.50 diopters, I have never worn any more powerful than my current -7.00, -7.00. But the optometrist said my vision in my left eye degraded. So maybe I should just increase the diopters of the right lens and leave the left at -7, since -7.25 would actually be a higher power than the lenses I am currently using?

Thanks again for your guidance.