Spectacles confusion
Discussion
I went for an eye test the other day because I know I need specs for driving / watching tv etc.
I got my prescription specs and, while I can now see well in the distance if I have them on I can’t read anything close up. Is this how glasses are supposed to work? It seems to me I’ve just swapped being short sighted to being long sighted. Surely specs should correct the problem rather than just swapping it round for the opposite? Or am I missing something?
I got my prescription specs and, while I can now see well in the distance if I have them on I can’t read anything close up. Is this how glasses are supposed to work? It seems to me I’ve just swapped being short sighted to being long sighted. Surely specs should correct the problem rather than just swapping it round for the opposite? Or am I missing something?
The Mad Monk said:
You may be missing something.
I think, first things first, go back to your optician and explain your perceived problem, let them tell you what their remedy is.
It may be that you need two pairs of glasses. One for distance, one for reading. or, possibly bi-focals.
My point is - I am short sighted. Are spectacles not supposed to correct that problem, rather than making me long sighted instead? Or do you require vari focals in order to have perfect vision? I’m trying to get a handle on it before I go back and raise it with optician I think, first things first, go back to your optician and explain your perceived problem, let them tell you what their remedy is.
It may be that you need two pairs of glasses. One for distance, one for reading. or, possibly bi-focals.
Normal vision person - You will see things in focus ~ 30 cm (near sight distance) to ~ infinity (far distance).
Long Sight person - you will see things in focus from ~ say 150cm (near sight distance) to ~ infinity.
Short sight person - You will see things in focus ~ 10cm to 6m (far distance) ie. anything beyond your far distance will be increasingly out of focus (6m in this example).
As you age, the goal posts (near and far distance) move closer together.
Bright light will help as it makes the pupil smaller (like a pin-hole camera), thus making the goal posts further away from each other.
So, the spectacles have enabled you to see normally, however, you may not be able to see things as close up as before.
(all distances given are for explanation purposes and not specific).
Long Sight person - you will see things in focus from ~ say 150cm (near sight distance) to ~ infinity.
Short sight person - You will see things in focus ~ 10cm to 6m (far distance) ie. anything beyond your far distance will be increasingly out of focus (6m in this example).
As you age, the goal posts (near and far distance) move closer together.
Bright light will help as it makes the pupil smaller (like a pin-hole camera), thus making the goal posts further away from each other.
So, the spectacles have enabled you to see normally, however, you may not be able to see things as close up as before.
(all distances given are for explanation purposes and not specific).
Knowing your age and your prescription would be useful in order to make a better informed comment.
However, if you've gone past your 40th birthday, try Googling 'presbyopia.'
Hardening of the crystalline lens inside your eye and weakening of the muscles that control its shape (both being age-related, usually) leads to your lack of ability to accommodate (focus at close distances). Hence, the jokes people make about their arms not being long enough to read a document, As their ability to accommodate has got worse and worse, the near distance they can see at has got further and further away.
It's important to recognise that 'accommodation' is not the same as 'short-sightedness.'
(I'm also going to completely disregard spectacle corrections for folks who are long-sighted here, in order to keep things less confusing.)
Let's give an example of one of the more usual scenarios that most will recognise. Mr X has been absolutely fine all through his life, wearing no specs at all for anything. Gets into his 40's and starts to realise he can't read as well as he used to be able to. Being a bloke, he refuses to believe that there's anything wrong with him and so he wings it for the next 3-4 years, until he absolutely has to visit the optician.
He will tell the optician that he's fine for seeing everything else, just not close stuff. He doesn't realise it, but presbyopia is taking hold (and will continue to get worse throughout the course of his life). Not to worry, this is easily cured with a pair of single vision reading specs which will have a plus (+) prescription. The plus lens is there to add power to the refractive ability, hence plus, and brings the point of focus back so that it is close to the wearer again. However, reading specs are there to give the best near vision only (in this instance, to correct Mr X's inability to accommodate), so the wearer won't be able to see across the room in them, let alone drive.
Making loads of assumptions here (as there are multi-variables to consider based on your age, prescription, ocular and general health - one size does not fit all) your situation is kind of the opposite of the example above in that you're short-sighted and can therefore see okay at near but your distance vision is blurry.
In very crude terms, your own eyes are acting as though they are a little bit too powerful in the way they refract light. This could be down to many things, including the curvature of the cornea, the axial length of the eyeball itself, the media inside the eye, formation of cataracts etc etc. The refracted light is being focussed by your eye in front of the retina instead of on it. Therefore, you are prescribed a minus (-) lens which has the effect of taking power away from your eye, hence minus. These minus lenses diverge light rays before they enter your eyes, enabling the focussed image to land on your retina.
All sounds good so far.
Except, if you are losing your ability to accommodate (which is not the same as being able to see at close due to short-sightedness), you won't be able to see up close, whilst wearing your single vision distance correction. And this is the opposite effect of the example above where someone wearing reading specs can focus at near but can't see across the room.
Hmmmm. If only someone could add a bit of extra plus power onto your lenses so that you could see up close, when you needed to....
Welcome to the world of varifocal lenses, I'm afraid! It's the best all-round solution to give you clear vision at all distances, in just one pair of specs. Separate pairs for distance/reading makes for optically superior results, but only for those specific tasks; continually swapping between different pairs is a faff that most patients can't be bothered with.
Bifocals are still a valid solution, albeit slightly outdated. They don't look great, with a visible line across the lens for starters. They also only work for distance and near, they don't correct what is known as your intermediate (or arms length) vision, which varifocals can do. For folks who are on screens or tablets all day, this is quite important.
Having said all that, I've had many myopic patients who are quite happy to wear a single vision distance prescription and just take their specs off to read.
Some folks go down the route of single vision contact lenses, wearing one lens for distance and one lens for near. This is known as monovision and is a lot easier to adapt to than it sounds. Multifocal contact lenses do exist, but my own experience of patient feedback is not positive, overall.
As I said earlier, one size does not fit all.
There are many, many factors to consider when prescribing and dispensing specs and everyone will have a different take on their own wants/needs/actual experience.
Best advice would be to discuss the options with your own optician. If you attend one of the bigger multiple outlets, try avoiding the Saturday boy/girl who likes working there because the frames are all such pretty colours. Speak to the optometrist or a dispensing optician, if you can.
(Hands up who can tell the practice was quiet this afternoon. Congrats to anyone who made it through all that gumph without nodding off.)
However, if you've gone past your 40th birthday, try Googling 'presbyopia.'
Hardening of the crystalline lens inside your eye and weakening of the muscles that control its shape (both being age-related, usually) leads to your lack of ability to accommodate (focus at close distances). Hence, the jokes people make about their arms not being long enough to read a document, As their ability to accommodate has got worse and worse, the near distance they can see at has got further and further away.
It's important to recognise that 'accommodation' is not the same as 'short-sightedness.'
(I'm also going to completely disregard spectacle corrections for folks who are long-sighted here, in order to keep things less confusing.)
Let's give an example of one of the more usual scenarios that most will recognise. Mr X has been absolutely fine all through his life, wearing no specs at all for anything. Gets into his 40's and starts to realise he can't read as well as he used to be able to. Being a bloke, he refuses to believe that there's anything wrong with him and so he wings it for the next 3-4 years, until he absolutely has to visit the optician.
He will tell the optician that he's fine for seeing everything else, just not close stuff. He doesn't realise it, but presbyopia is taking hold (and will continue to get worse throughout the course of his life). Not to worry, this is easily cured with a pair of single vision reading specs which will have a plus (+) prescription. The plus lens is there to add power to the refractive ability, hence plus, and brings the point of focus back so that it is close to the wearer again. However, reading specs are there to give the best near vision only (in this instance, to correct Mr X's inability to accommodate), so the wearer won't be able to see across the room in them, let alone drive.
Making loads of assumptions here (as there are multi-variables to consider based on your age, prescription, ocular and general health - one size does not fit all) your situation is kind of the opposite of the example above in that you're short-sighted and can therefore see okay at near but your distance vision is blurry.
In very crude terms, your own eyes are acting as though they are a little bit too powerful in the way they refract light. This could be down to many things, including the curvature of the cornea, the axial length of the eyeball itself, the media inside the eye, formation of cataracts etc etc. The refracted light is being focussed by your eye in front of the retina instead of on it. Therefore, you are prescribed a minus (-) lens which has the effect of taking power away from your eye, hence minus. These minus lenses diverge light rays before they enter your eyes, enabling the focussed image to land on your retina.
All sounds good so far.
Except, if you are losing your ability to accommodate (which is not the same as being able to see at close due to short-sightedness), you won't be able to see up close, whilst wearing your single vision distance correction. And this is the opposite effect of the example above where someone wearing reading specs can focus at near but can't see across the room.
Hmmmm. If only someone could add a bit of extra plus power onto your lenses so that you could see up close, when you needed to....
Welcome to the world of varifocal lenses, I'm afraid! It's the best all-round solution to give you clear vision at all distances, in just one pair of specs. Separate pairs for distance/reading makes for optically superior results, but only for those specific tasks; continually swapping between different pairs is a faff that most patients can't be bothered with.
Bifocals are still a valid solution, albeit slightly outdated. They don't look great, with a visible line across the lens for starters. They also only work for distance and near, they don't correct what is known as your intermediate (or arms length) vision, which varifocals can do. For folks who are on screens or tablets all day, this is quite important.
Having said all that, I've had many myopic patients who are quite happy to wear a single vision distance prescription and just take their specs off to read.
Some folks go down the route of single vision contact lenses, wearing one lens for distance and one lens for near. This is known as monovision and is a lot easier to adapt to than it sounds. Multifocal contact lenses do exist, but my own experience of patient feedback is not positive, overall.
As I said earlier, one size does not fit all.
There are many, many factors to consider when prescribing and dispensing specs and everyone will have a different take on their own wants/needs/actual experience.
Best advice would be to discuss the options with your own optician. If you attend one of the bigger multiple outlets, try avoiding the Saturday boy/girl who likes working there because the frames are all such pretty colours. Speak to the optometrist or a dispensing optician, if you can.
(Hands up who can tell the practice was quiet this afternoon. Congrats to anyone who made it through all that gumph without nodding off.)
From practical experience I'd agree all the above. I'm badly myopic - far point just 15 cm. Brilliant for close work but that's a limited party trick. For many years I got by with contacts, including varifocals where my optician used me as a guinea pig for new ranges. Contacts give a very good field of vision compared to glasses - helpful when I used to fly. As presbyopia took its toll I started to use off the peg reading glasses on top but that was an increasing faff.
When I stopped work I tried bifocal specs but found them dangerous. When descending stairs, or just stepping off a kerb you're looking through the near vision segment which was a blur.
I then tried varifocal specs from the big S. They were one rung down from the top price range. Big S give you a leaflet claiming to demonstrate the different field of vision you can expect from different price ranges. To put it mildly, I was disappointed and never comfortable with them. With hindsight the frames were far too shallow to accommodate a decent varifocal lens. And I was seeing double. I then went to a proper independent optician. A thorough eye test showed I needed prism correction to correct the double vision and a much deeper/taller frame to accommodate sufficient variation in power. The end result cost an arm and a leg but was a revelation.
I'm not saying you can't get good varifocals from a chain optician - I'm sure you can - but to me it seems a bit of a gamble unless you can get some form of satisfaction/money back guarantee. And as said above, avoid the Saturday morning trainee.
That said, I do have a couple of friends who are comfortable juggling 2, if not 3, pairs of single-vision specs for different purposes.
Good luck whatever you choose!
When I stopped work I tried bifocal specs but found them dangerous. When descending stairs, or just stepping off a kerb you're looking through the near vision segment which was a blur.
I then tried varifocal specs from the big S. They were one rung down from the top price range. Big S give you a leaflet claiming to demonstrate the different field of vision you can expect from different price ranges. To put it mildly, I was disappointed and never comfortable with them. With hindsight the frames were far too shallow to accommodate a decent varifocal lens. And I was seeing double. I then went to a proper independent optician. A thorough eye test showed I needed prism correction to correct the double vision and a much deeper/taller frame to accommodate sufficient variation in power. The end result cost an arm and a leg but was a revelation.
I'm not saying you can't get good varifocals from a chain optician - I'm sure you can - but to me it seems a bit of a gamble unless you can get some form of satisfaction/money back guarantee. And as said above, avoid the Saturday morning trainee.
That said, I do have a couple of friends who are comfortable juggling 2, if not 3, pairs of single-vision specs for different purposes.
Good luck whatever you choose!
Edited by millen on Wednesday 28th November 22:05
millen said:
I'm not saying you can't get good varifocals from a chain optician - I'm sure you can - but to me it seems a bit of a gamble unless you can get some form of satisfaction/money back guarantee. And as said above, avoid the Saturday morning trainee.
I agree with you and the overall (general) observation re: chains/multiples. And, on these same lines of generalising, there will be many totally satisfied patients from a chain experience as indeed there will be dissatisfied patients from an independent practitioner experience. No argument there.Edited by millen on Wednesday 28th November 22:05
However, it's more likely that you will be given the time to discuss your needs with an experienced and qualified person, if you are in an independent environment. The options are also likely to be more extensive, rather than a short and set-list of lenses.
Everyone's mileage may vary, I accept that.
A major part of the service I give in my practice is - sounds really lame but it's true - just sitting down and discussing lenses and lens options with patients. It's as simple as that - giving people all the time they need with clear explanations. How the lenses will work for them, what to expect. What not no expect. The options that will work well for them. The advantages of choosing certain lenses, depending on prescription.
This can take 10 minutes. It can take several visits and several hours.
And, as important, explaining the downsides. Where things will not be quite so great; a varifocal lens, for instance, has to do the job of several lenses in just one lens. There's going to be compromises.
I've talked many a patient out of an untold number of Photochromatic/Transition/Reactolite dispenses, because they wanted them for driving (modern UV filtered-windscreens make sure the lenses don't go dark enough).
I've got a great picture up on the wall with which to explain astigmatism to patients.
90% of new patients haven't had these kind of explanations before, they associated the word 'astigmatism' with some sort of horrible, rare disease.
Sounds obvious, no?
You wouldn't believe the amount of folks I've talked to over the years who have been dispensed varifocal lenses from elsewhere (at no inconsiderable expense), with no explanation of how they will work for them, adaption techniques etc.
Usually the Saturday-morning type of employee is involved but, being fair, it's because they are under pressure to push certain products and upgrades. The specs just end up being thrown in the drawer and the poor patient gets to tell all their pals in the pub that varifocals are rubbish, they're a total waste of money and I'm really peed off!
Then they come to me, I explain it all to them, they go away, report back that - yes - now I know how to work them, they're brilliant!
They weren't patients of mine before but they'll be back, though. And all their family/mates/work colleagues, more than likely.
Well, hopefully!
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