-7.75 binocular - which glasses should I get?

Hi guys I’m Ben.

I am -7.75 in both eyes, with +.5 astigmatism in one eye.

I see that Zenni has a black friday sale now, so I was going to order many pairs of $7 glasses that would help me throughout the journey.

My immediate goals:

  1. To get a near complete set of glasses to finish my journey towards 20/20 (I expect this to take 2+ years)
  2. To get a set of differentials for computer work

Being that I’m -7.75 binocular now, I was thinking of getting the following glasses to store:

  1. -7 (no astigmatism correction)
  2. -6
  3. -5
  4. -4.5
  5. -4
  6. -3.5
  7. -3
  8. -2.5
  9. -2
  10. -1.75
    • 1.5
  11. -1.25
  12. -1
  13. -.75
  14. -.5

Does this list make sense? Given that they are cut for the same frame I can mix and match as needed. Am I on the right track? What should I adjust about this plan?

Thanks for reading!

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As your eyes are pretty close in refraction, I would expect no need for mixing and matching if you have the patience for the weaker eye to catch up each time. The only hesitation I would have is about the choice of frames and getting the PD right. If you have the PD noted on the prescription for your current glasses, that should be fine. But pupillary height can also be an issue, and this is a bit of a gamble, as one cannot specify this on a Zenni prescription. A good optician marks the pupillary height as well on the instructions to the lenscutter.The price of Zennis goes up with higher diopter lenses, so if you get this wrong, you may waste a lot of money.

I see that you are going for .50 reductions until you get to -2. This is rather ambitious, but on the other hand, you can always order more in between glasses if you find this to be the case.

My advice is to order only one pair of norms and one pair of diffs to start off with - there will be other sale offers in the future. I ordered too far ahead, and regretted it. I discovered, when I started taking lenses out of the frames, that the PD for the two eyes is not the same, that the left eye has a different pupillary height than the right, that the axis of astigmatism is variable in the left eye, that I overestimated the potential rate of reduction of astigmatism in the left eye relative to the reduction in spherical, and that the right eye improved much faster than the left = 14 pairs of pretty useless glasses, in spite of being able to mix and match. This is not a great disaster for me, as my much stronger right eye has allowed me to be uncorrected most of the time, and I have not had to buy replacement glasses. But with your degree of myopia you may end up having to replace glasses - or you might just get lucky on the fit of the frame, the PD and the PH.

Depending on where you live, you might also run into trouble with import tax on such a big order.


I would second this. Just take it slow. You’ve got ages to go and heaps to work out. Once you’ve done 3-4 glasses reductions then maybe think of buying in bulk. But don’t buy in bulk straight off the bat.

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Yes, I have my PD. (dual PD numbers)

I thought about the height problem, and my thought was that I could adjust the nose pads for height changes if necessary.

The reason I wanted a complete set is because I am not sure what I should be using for differentials for different tasks (ex: desktop computer use vs laptop use).

No import fees in my country and Zenni seems to be the same price for all diopters unless I go with a higher index.

Where should I start re: differentials? A concern is that my edge of blur could be different throughout the day and depending on the task/screen.

Thanks for the replies.

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For differentials it all really depends on your work setup and how far you are away from the screen. You should be finding an ergonomic distance. Usually its about 60cm for a normal sit down desk. You need to work out the right diopter reduction that suits you. Its usually around 1-2 diopters. I wouldn’t worry too much about your edge of blur changing too much throughout the day.

Check the wiki for some basic guidance. Also for most general other queries.

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I’m about 75cm away, and even with my -6.75 lenses I seem to be okay. So I don’t know how much lower I should go since I’m not at the edge of blur yet.

You could use the EM suggested diopter reduction for differentials, with the advantage that you can adjust your distance to screen according to whether you overshoot or undershoot a little. Perhaps you could go for two pairs in the appropriate range, as the second will come in useful at some stage, either as the correct diffs or new norms.
Adjustable nose pads are fine if the optical centre of your lenses needs to be raised, but not if it needs to be lowered, as in my case. I can only see through the optical centre of the left lens if I lower the glasses on my nose, which also increases the vertex distance a little and puts some pressure on the ears. As I only use these glasses for measuring it does not matter.

Good luck, whatever you decide.


Obviously lower, but it is up to you to ‘guess’ how much lower, as is/was the case for all of us. As you are new, just a small reminder not to ask for or give specific diopter advice. :slightly_smiling_face:

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What’s your cm measurement to blur?

If you can move the screen or your chair, get differentials that give you clarity at 50 or 55cms. And work your way up to the max comfortable distance (80 to 90cms for me), and then drop to ~55cms again.
As @Ursa said you can always move 5cms closer if you have to for clarity (just make sure your posture is good in front of the screen), but try to work at the max distance. “Just within blur” alternated with “just outside of blur“


well having almost no astigmatism helps, but ordering all the glasses at once is still not a good idea

also, you don’t even know your good differentials/normalised yet, so start with finding that and THEN you can order 0.25 steps down
your jumps of 1D and 0.5D will get you nowhere besides blur-tolerance and will stall your progress

also, 2+ years is a nice optimistic view to put it lightly

more realistic is 0.25 per 3-4 months so you’re looking at more like 8-9 years, plus if you get that far, the last diopter (acc. to reports on here) takes much longer, so a 10 year plan is more what you should be thinking about. In that context, ordering so many glasses ahead of time is pointless. I’d stick to max 2 at a time

it also depends on your lifestyle. If you get outside a lot and get good at active focus and don’t reduce too fast you can make good progress.
personally, from my TOP prescription (over-prescribed) in just over a year I’ve managed to reduce about 1D and 0.25 D of astigmatism, not all of which is real reduction due to over-prescribed starting point and that’s glasses. in contacts only reduced about 0.5 D (look up vertex distance)

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If you are really bent on taking advantage of the sale use your measurements to make some solid guesses about what you need for the next year. Hint: There will most likely be another black friday promo next year, at which point you will know so much more about how to proceed,

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I’d say, make 0.5 reductions till -6 and then go by 0.25.
Don’t reduce by 1 if you want to go by the most current EndMyopia principles.

My cm measurement to blur came out to somewhere between 19.5 and 20 cm. Giving me a rating of about -5-5.25 diopters.

Seems a lot lower than -7.75.

With this info in hand, should I grab a pair of -5.25s and call it a day for now?

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As we’ve all been saying. We shoudn’t give diopter specific advice.

I think @Ursa previous comment was constructive. For your differentials work out generally what your CM to blur is and buy a few pairs of glasses around that diopter with 0.25 increments. Once you’ve got you’re glasses you’ll be able to make slight adjustments to you workstation that will be more comfortable.

Hope you get some good savings on black friday!

Oops sorry. The question just comes to me naturally.

OK. I will try to get a couple pairs in that range. Thanks again everyone. Will report back with results.

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I understand you are triggered by the BF deals.

Just keep in mind that under normal circumstances the recommendation is to take several measurements, after different activities at different times at different lights and work out the average.
This way you understand your habits and your posture / ergonomic distance from screen better.
However, I’d say if your work means sitting at a desk and you can move the screen / keyboard / chair, you have room to play with the diopter (sit at 50cm instead of the current 70cms, until you can gradually go back to 70cms)

As for the measurement: you measured the distance to blur, converted to diopters and now you need to judge how representative that measurement was and if you drop 0.25 or 0.5 from it to create the blur challenge. (Challenge = possible to clear, not just a constant blur)

As you’ll order glasses based on one measurement (not average over time), be aware that you may have to make adjustments later.
Worst case you’ll order your future 3 or 4 glasses now (I wouldn’t buy more, Zenni is cheap on any day).
Whatever you do, keep measuring to learn what affects your visual clarity most, and keep trying patiently until you have found what works for your eyes.

This is all assuming you already know what differentials / normalised / full prescriptions are and what to use them for.

There will be other sales in the future, and you could be collecting interest rather than paying it if you buy some of those lenses later, never mind the storage of such a collection. Average improvement is 0.25D every 3-4 months. So a year of normalized and differentials is 6-8 pairs. If you’ve not found edge of blur yet, and you might get the first diopter quickly from pseudomyopia relief, then filling out the second year’s supply is reasonable. Your current plan has full diopter leaps in the beginning, which I think you’ll regret.

Agree with everything said here. Assuming equal reductions in each eye along a linear path may be problematic.

There is no way to know – in advance – how your eyes will progress.

You could end up in a situation like @Ursa where one eye advances rapidly while the other meanders.

I must add here that this only happened because I was doing EM without correction of any kind, so there was no way I could hold back the faster eye by refusing it a reduced lens before the other had caught up. Very few people would find themselves in such a situation. Quite apart from that, I do not really see the point of holding back an eye that is eager to improve, unless it means that the other eye is deteriorating as a result. My weaker eye was lagging behind by about 6 months, but it still improved. Being uncorrected means my binocular vision is determined by the stronger eye, so my left eye can amble along while I enjoy -1 binocular vision. I see much better with both eyes, in spite of the big spherical and cylinder diopter gap

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you’re measuring to your eye which gives you a contact lens prescription, so glasses’ll be a bit higher diopters (apply vertex distance formula)

and at the start everyone is inaccurate with cm measurement to blur, so I would get better at measuring till the first HINT of blur