Confused about glasses prescription

[JamesBlond]

I currently have a pair for distance vision. The prescription is -2.50. They are fine.
I also have a pair for computer use. The prescription is -1.50 (from a separate eye test). They are also fine.

I now want to get some progressive glasses online, but they ask not for the two prescriptions, as expected, but for the distance prescription plus an ADD.

My distance prescription came with an ADD of +1.75 though I've no idea how that was derived and it doesn't add up because as far as I understand it, the actual ADD, given the two separate prescriptions above, should be +1.00. Is that correct?

If so, then okay, but that means the ADD system is useless... Why do they do it that way rather than test distance and close vision separately? Am I missing something?

[CharlieH]

I would drop an email to the company explaining the two prescriptions -2.50 /-1.5 and seek their guidance.

[JamesBlond]

20 minutes ago, CharlieH said:

I would drop an email to the company explaining the two prescriptions -2.50 /-1.5 and seek their guidance.

Will try that, though I have a suspicion they will say they need the ADD on the distance prescription - in any case, on their website they give no indication that there is any other way of doing it, and as far as I can see after ages searching the web, I am apparently the first person ever to raise the question. 

[JamesBlond]

Just to throw another spanner in: when I tried some ready-made glasses for computer use, the best strength was -2.25. -1.50 was way off. I can't see any logic in how that accords with my actual prescription.

[CLS]

The ADD is for reading distance only as it adds 1.75 to the lower part of the eyeglass only, resulting in -0.75 in your case.
You cannot combine monitor distance and long distance.


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[steve187]

get a fresh eyesight test

[JamesBlond]

27 minutes ago, CLS said:

The ADD is for reading distance only as it adds 1.75 to the lower part of the eyeglass only, resulting in -0.75 in your case.
You cannot combine monitor distance and long distance.


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Sure, but ADD = distance diopter minus reading diopter, right?

Are you suggesting I should still use the +1.75 ADD to get the progressives rather than the actual +1.00 (proven by experience)?

 

This is mightily confusing. I hear that ADD is simply an estimate but I've no idea why they would want to do it that way rather than do a definitive test.

[JamesBlond]

33 minutes ago, steve187 said:

get a fresh eyesight test

Well, I've had two separate eye tests and both those prescriptions are fine - don't want to go through it again. Also, it's not easy to find an optician that will just do a test - they really just want to sell frames.

By the way, please no one suggest going to Rutnin - I once went there a few years ago and it took half a day and cost about 1,200 baht, and I had to press them to give me the prescription at the end as they didn't seem to want to do so. I think that place is really for a medical exam rather than just a refraction test.

 

I'm really hoping for an explanation of the ADD system and whether the best thing is to use my actual ADD or some kind of formula.

 

[CLS]

First of all what do you want to achieve? Get rid of 2 glasses?

If you want to be able to read a book while wearing glasses, then add 1.75 for the long distance one and 0.75 for your computer glasses.

By adding 1.75 your eyes are 1.75 diopter under-corrected, giving you a focused vision at 60cm (1m/1.75) distance, assuming your eyes don’t accommodate any longer

Adding 1.75 to long distance glasses is quite a standard value.
I had it too for a few weeks, but changed to standard glasses. I don’t support progressive glasses. Was feeling dizzy while wearing.
Now, I take off the glasses for reading.



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[JamesBlond]

10 minutes ago, CLS said:

First of all what do you want to achieve? Get rid of 2 glasses?

If you want to be able to read a book while wearing glasses, then add 1.75 for the long distance one and 0.75 for your computer glasses.

By adding 1.75 your eyes are 1.75 diopter under-corrected, giving you a focused vision at 60cm (1m/1.75) distance, assuming your eyes don’t accommodate any longer

Adding 1.75 to long distance glasses is quite a standard value.
I had it too for a few weeks, but changed to standard glasses. I don’t support progressive glasses. Was feeling dizzy while wearing.
Now, I take off the glasses for reading.



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I want progressives to avoid changing glasses whenever I go to the computer, which is about 100 times a day. Not needed for books - I can read books without glasses - but I do need glasses for the computer.

 

Thanks for the advice, but I'm not sure where 0.75 comes from. My -1.50 computer glasses were specifically tested for computer use, so surely the addition should be 1.00.

 

Hmm... could it be that your progressives didn't work because they used the 'standard' 1.75 addition...? This is what I'm afraid of. Progressives are expensive so I wouldn't want to trust some kind of generic formula, even if that's what the online glasses companies are demanding.

 

So far I'm still thinking that if I have to use the ADD system for getting progressives, then I should use +1.00 rather than the optician's method, which, to be honest, seems wacko to me.

 

[CLS]

My ADD 1.75 values came from the optician. But you can only find it out whether you support them or not by wearing a few days/weeks.
As I said in my initial reply you cannot correct intermediate and long distance with one eyeglass. Only a combination of long/short intermediate/short distances can be corrected


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[JamesBlond]

13 minutes ago, CLS said:

My ADD 1.75 values came from the optician. But you can only find it out whether you support them or not by wearing a few days/weeks.
As I said in my initial reply you cannot correct intermediate and long distance with one eyeglass. Only a combination of long/short intermediate/short distances can be corrected


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Crikey, that's big news to me. All the information I've seen doesn't mention that progressives don't work for intermediate/long distance combo. I'm far from understanding the physics of it, but if it's true, then the general information being put out is highly misleading. I've just checked a few more websites and they are all blithely saying they are good for intermediate and distance. Not that I particularly believe them. This is going to take a lot more research...

 

As to the ADD thing, I still don't understand why opticians extrapolate near/intermediate vision from distance vision rather than doing an actual test. It's like asking an optician what time it is and they say "well, it was nine o'clock about three hours ago".

[CLS]

As compromise you could use -2.0 with bigger fonts on your monitor.
With progressives you cannot achieve what you want.


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[CLS]

Progressives are only different on the lower part of the eyeglass, where the ADD kicks in. But for intermediate/long distances your eye uses the center and upper part. That’s why a combo is impossible.


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[JamesBlond]

8 minutes ago, CLS said:

As compromise you could use -2.0 with bigger fonts on your monitor.
With progressives you cannot achieve what you want.


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I think as a compromise I would probably use my computer glasses for long sessions on the computer, and keep the progressives on for quick visits to the computer - to check an email or jot down some notes. Even that would be a huge boon.

 

As to what ADD to use - unless there is some genius in the optician's extrapolatory formula (whatever that is) that is eluding me, I think I'd rather use the tested, actual diopters from the seperate prescriptions.

[JamesBlond]

12 minutes ago, CLS said:

Progressives are only different on the lower part of the eyeglass, where the ADD kicks in. But for intermediate/long distances your eye uses the center and upper part. That’s why a combo is impossible.


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My intention was to have the intermediate ADD for the lower part and do without reading distance altogether. I know that would mean looking at the screen out of the bottom part of the glasses - no problem.

[CLS]

With your long distance progressives you will be able to see the keyboard focused, but your monitor will be blurred. (Assuming you have a desktop and monitor)
With a laptop your long distance progressives are useless.



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[CLS]

If you want to use the lower part to look at the screen, your head is pointing to the ceiling. Is gonna give you a neck ache.


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[DaRoadrunner]

Have you ever tried using progressives before? I have.... horrible. So now I have three pairs; one for distance, one for computer and one for looking at girls.

[CLS]

Have you ever tried using progressives before? I have.... horrible. So now I have three pairs; one for distance, one for computer and one for looking at girls.

Is the pair for the girls tinted?


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[AAArdvark]

9 minutes ago, DaRoadrunner said:

Have you ever tried using progressives before? I have.... horrible. So now I have three pairs; one for distance, one for computer and one for looking at girls.

I have used progressives for 20 years and have no problem.  I cannot tolerate bifocals, however.  Your brain has to learn where to look through the progressives and it takes a while.  You may also have to learn to tilt your head subconsciously.  It is also a person by person thing.

There are people who wear multi-focal contacts or cataract lenses.  For a percentage of people they work and give amazing results like close ups to near telephoto vision.  I do not remember what the percentage is but I'm not one of them.  

[JamesBlond]

For my purposes progressives will be fine. If I have to tip my head back a bit, sit higher above the screen, or push the glasses up on my face a bit to see the computer - no problem. Anything to avoid the tedious switching of frames when just popping to the computer. I have used progressives before though at that time the Paris-Miki optician did all the measurements and I have no idea whether the ADD method was used (though I seem to remember insisting on having a seperate intermediate-vision test).

 

As I won't be using an optician this time, this thread is about whether it is possible to calculate my own ADD figure with reference to two good presciptions, thereby overriding the optician's 'official' addition. I guess I'm just finding it hard to believe that opticians do it differently. I thought maybe there is good reason for them to use the ADD system, but actually, I'm beginning to suspect that the large number of people who have had a bad experience with progressives are victims of this apparently haphazard method and would have fared much better if they'd had separate near and distance tests.

[CLS]

For you ADD 1.0 for computer use, for the others ADD 1.75 or 2.0 for reading (as the ADD value is supposed to)


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[mahjongguy]

As it happens, I went to my optician this morning. She's terrific and has bailed me out from a problem no one else in Pattaya or Bangkok could understand.

 

I mentioned this thread to her. My takeaway is this:

- You should be able to get progressive lenses made if you consult in person with a good optician. But there's no way an online service could deal with your unusual request. 

- If you were her customer, depending on your answers to specific questions about how you would use them, she would probably try to talk you out of it.

 

So, it seems likely to me that if you try to save money by ordering online you take a very big risk of wasting it all.

[lujanit]

1 hour ago, mahjongguy said:

As it happens, I went to my optician this morning. She's terrific and has bailed me out from a problem no one else in Pattaya or Bangkok could understand.

 

I mentioned this thread to her. My takeaway is this:

- You should be able to get progressive lenses made if you consult in person with a good optician. But there's no way an online service could deal with your unusual request. 

- If you were her customer, depending on your answers to specific questions about how you would use them, she would probably try to talk you out of it.

 

So, it seems likely to me that if you try to save money by ordering online you take a very big risk of wasting it all.

I have used progressives for about 15 years (since contacts became a real pain).  For about 10 years I have used the online Zennioptical store and cannot complain about their price or service.  The original recommendation came from this forum.

 

I use Dr Paradon at St Louis hospital (Surasak) for the prescription.  He gives you a full eye examination plus the necessary prescription any eyeglass manufacturer would need.

[mahjongguy]

I agree that Zenni offers good value but it's unlikely that they can successfully manage this unusual request. The OP wants progressives that cannot be used for reading.

[JAS21]

20 hours ago, mahjongguy said:

I agree that Zenni offers good value but it's unlikely that they can successfully manage this unusual request. The OP wants progressives that cannot be used for reading.

I bought progressives from Zenni ... however for driving my head is not really at a comfortable level but I can also read the various 'dials'etc.

 

For computer use and reading not exactly successful either ... just hang a pair of the correction near your screen ...I do now ...

[watcharacters]

 

Progressives sound great but remember with them you can only read where your nose is pointing.  I had to move my head back and forth just to read a newspaper column.

 

I returned the progressives to the shop when I bought them for a refund.     ($450 30 + years ago)

[BritManToo]

31 minutes ago, watcharacters said:

 

Progressives sound great but remember with them you can only read where your nose is pointing.  I had to move my head back and forth just to read a newspaper column.

 

I returned the progressives to the shop when I bought them for a refund.     ($450 30 + years ago)

I started wearing progressives 15 years back, wouldn't use anything else now and at $50 from Zenni, hardly expensive.

[JamesBlond]

On 5/11/2019 at 1:51 PM, mahjongguy said:

I agree that Zenni offers good value but it's unlikely that they can successfully manage this unusual request. The OP wants progressives that cannot be used for reading.

That is surely misleading advice. Why is it considered an unusual request? I had a pair of progressives before with the bottom part for computer use - that was my particular request to Paris-Miki and they weren't surprised about it. Those worked perfectly well for several years and I would still be using them now if the coating hadn't came off the lenses (which I assume was planned obsolescence). Yes, I had to move my head about a bit to see everything, but I soon got used to that.

 

Actually, I didn't intend the thread to become a discussion as to the pros and cons of progressive lenses. Really, it is only about using the opticians' ADD method for progressives. I was unsure about this at first, but now I am sceptical about applying a standard (estimated) figure to determine near vision and would like to know if there could be any reason/advantage in doing it that way rather than using actual, separate tests for near and distance vision. As I can't find any explanation of this anywhere on the internet, I'm beginning to assume it is just laziness on the opticians' part.

 

Well, I'm going to calculate my own ADD figure from my two prescriptions (which is 1.00), get some progressives online in this way, and report back anon.