2-Week "Adaptation" period?

[PAL]

I've heard some Opticians specify a minimum of 2 weeks use for a patient to try a new PAL lens.

I'm wondering what others think about this, and if it has any basis in scientific fact.

It seems to me there are 3 possible outcomes:

1) the patients body (eye/lens/muscle/etc) actually change shape so that the optical image is painted differently on the back of the eye. Seems unlikely.

2) the patients brain learns to correct poor image information (outside the sharp corridors of the PAL). Sounds not only unlikely but impossible.

3) the patient just learns to deal with a bad lens. I think this is what the real hope is for the Optician; that the patient just gives up and finds ways to deal with the poor image, by things such as bending their head around, carrying a 2nd pair of glasses, getting help from friends, etc.

So I'm wondering what other opinions are.

More importantly, what is the scientific basis for the "2-week" period, meaning point us to actual studies that show the results have a basis in physiology.

Thanks for other opinions and facts.

[drk]

All vision correcting devices have drawbacks...all of them. No one can change that.

Hey, the patient is responsible, too, for solving their own problems. They need to make educated choices and buy in to the treatment program.

Clinicians need to know the best treatment plans, try to individualize them, and then seek feedback as to success.

What are you looking for? Perfection?

[TLG]

I think this is what the real hope is for the Optician; that the patient just gives up and finds ways to deal with the poor image...

You sound more like a dissatisfied customer than an 'optical retailer'. Real - or at least good - opticians don't rely on 'hope' for positive outcomes.

[HarryChiling]

Assuming that the prescription is accurate to the patients needs. Consider that their are many different forms that can be considered "Best Form" and in the here and now we have freeform processing which allows for a much broader range of definitions to "Best Form". In cases where I have told a patient to try them for two weeks it is often because I know the Rx is as prescribed and the patients VA is what it should be. That leaves the adaption and that could be to the particular design. In many cases it does mean the patient needs to adapt to the particular designs benefits and drawbacks. Unfortunately manufacturers don't supply data about their designs, this knowledge used to be common in the earlier part of the 20th century, your lenses would be makred with a Power, and degree of rotation and often the names gave you and ideal as to what design philosophy was used.

In short, Number 2, except it's not that the patients brain learns to correct poor image information. To oversimplify it the brain just learns to ignore poor image information. The difference with PAL's is that the brain may need to learn to ignore information from a different area of the lens than what they were currently used to and this is where the adaption period comes in.

[Striderswife]

You sound more like a dissatisfied customer than an 'optical retailer'.

I kind of thought the same thing, but I'm going to reply anyway.

I tell patients that everyone is different in how they respond to a new Rx (in any lens form, SV, BF or Multifocal). Some people put them on and an hour later, it's like they've had them all their life. Most people take a few days to really be comfortable in new glasses. Occasionally, I will have patients that can take about two weeks to adapt, and it takes some real practice and dedication to really be comfortable. But for most people, you'll know in about two weeks if you're going to adapt or not. If it's been two weeks, and you're still not comfortable, there may be something that needs to be addressed (which is a laundry list of things, too individual to get into here).

[Barry Santini]

It's really not mainly about change in image clarity. Its about change in visual perspective and preception. Nature has designed Our senory apparatus to be very sensitive to *changes* in stimuli. Since 90% of our information about the world comes through our eyes, it stands to reason that through oureyes will come a significantly greater amount of sensitivity to changes about our visual enviroment.

The best book I seen on this subject for the lay reader so far is SENSATION AND PERCEPTION. It should be a MUST in the optical schools, IMHO.

Barry

B

[PAL]

I don't think I was clear enough about option 3 (the patient just gives up and finds ways to deal with the poor image).

I am not talking about "adaptation" in the sense of a patient becomes "comfortable" with their new lenses.
I mean it in a totally different sense, and I'll say it again: poor image.
That does not mean at all "comfort". It means how well the lens resolves image details in different zones.

I also do photography, and there is no such thing as the camera "adapting", or learning to be "comfortable".
There is actual science and physics involved in the optical image, and I won't buy a lens without studying the MTF chart for it, because I want to know how it optically performs.

Now I've talked with many patients who do "adapt" to their new lenses, and find they work just fine for their typical activities.

However, I am talking about something completely different.
I will even give an example "hoping" this makes it more clear (yes this is for TLG):
I have seen opticians and vendors claim that the distorted image outside the intermediate corridor will improve and the corridor will appear wider to a patient after a week or two of "adapting". Yet I've never seen a patient who could actually resolve more detail after adapting.

So once again, where is the science and the physics?

I would expect an actual *measurable* change, such as being able to resolve more LPI in a resolution test chart, yet I have never seen this done.

So far, it looks like I'm the only one who's looking for this type of facts and data, but I'm hoping I'm wrong.

End of rant...

[uncut]

Brain adapt! You know.......like riding a bicycle, PAL. I think you are expecting too much "ability" from the SUV of lenses, the so called progressives, to do everything. I detect from your posting that certain tasks are difficult. Sometimes, a task-specific lens can make people more comfortable/functionable(truck). For precarious, high speed tasks a SV lens does a better job(convertible) and increases accuracy. Some occupations may require higher or lower powers, or heights of progressives(van).

Sometimes you need a bicycle..........just ask an engineer!

[optical24/7]

What you're asking is an absolute, formulamatic way to judge optical performance of a given lens design. We can do this with fixed, factual instrumentation designs ( telescopes, camera's, ect..) But when dealing with individual patients particular demands includes physiological and perceptional ( Just as Barry stated) and psychological, We've got another set of equations to factor in.

One patient may adjust quite quickly to a big power change, but the next is uncomfortable with a small one. I love the words * Neural Adaptation*. I use it often with patients, Some will be comfortable almost immediately, but others need that * N A* time. If a patient isn't comfortable in 2 weeks, then some type of change is in order ( usually).

And just as with PAL's...There is no "one size fits all best". Each patient brings their own needs/wants/expectations along with adaption issues to the table. All we can do is be as well versed on lens designs and similar outcomes/expectations met with particular designs in similar circumstances. Bottom line....there ain't no science to it... ( to a degree..) I believe all one can do is be knowledgeable of differing lenses/treatments/usual benefits that will aid the patient to have the visual experience they expect...( not always possible :bbg:)

[braheem24]

I also do photography, and there is no such thing as the camera "adapting", or learning to be "comfortable". There is actual science and physics involved in the optical image, and I won't buy a lens without studying the MTF chart for it, because I want to know how it optically performs.

You use your 85mm f/1.4 the same as your 300mm f/6.3? I'm assuming you change your ISO, shutter speed, You slowly learn which has barrell distortion, which has Pincushion, which can be used wide open and which has to be stopped down, you even learn all of these conditions are variable on the lighting conditions and learn to trust the meter instead of your eyes because they are constantly adapting to the enviornment.

Just when you think you've learned everthing there is to know about your lens, You buy another body and realize you have learn about it's idiosyncrasies all over again.

or better yet, just when you think you know everything about your visual system, you buy another pair of glasses and have to learn it's idiosyncrasies all over again.

[scriptfiller]

I educate PAL wearers at dispense (especially first timers) that we see with our brains. Our brain is like the CMOS sensor in a camera, it takes the information fed to it through the lense and records the image. If the dispense is later in the day I will inform Pat's. that they have adjusted to seeing things in a different way and there is going to be a change in the way they see with the PAL's. I always tell them to wear their new specs. the first thing in the morning the day after dispense. That way the brain starts with the PAL's as a frame of reference for image formation.

I don't think there is an exact quantifiable way to measure PAL adaptation.

[Barry Santini]

Human vison is KNOWN to adapt to a poorly focussed image through the mechanism of enhancement of image contrast. Think of your sharpness control on your TV, which simply accentuates the "edges" (borders) of images. Think the CSI shows where an out-of-focus license plate is sharpened through software enhancement (just like your brain)

In a book by the famous eye surgeon Jack Holliday, he spends a whole chapter at the back of the book counciling surgeons who perform refractive surgery to advise their client that it may take UP TO A YEAR for their vision systems to fully adapt and relaize the best vision after refractive surgery.

I believe that the "glial" cells are the tools of this enhancement phenomenon. I also speculate that parts of the mechansism known as emmtropization is involved in this visual enhancement.

FWIW

Barry

[Barry Santini]

Yet I've never seen a patient who could actually resolve more detail after adapting.

So once again, where is the science and the physics.

As far as I can see, your initial premise above is not based on scientifically or statistically valid procedures. It seems to be just your anecdotal summation.

Let's start with real testing BEFORE we favor the conclusion you site.

Barry

[drk]

If you are trying to refute actual psychophysical improvement in, say, field of 20/20 view 5 mm into corridor "X" at add power "Y" on patient population "Z", I'm with you. I doubt any miracles occur whereby the visual system can decipher the blur outside the specified zone (although I'd bet a little blur interpretation improvement occurs).

Nonetheless, we are not testing Hubble telescopes, just people. They have to be as happy with their glasses as their cotton underwear or microwave oven. Nothing's perfect, man.

[Sphinx]

Harry?

The original poster sound virtually identical to a customer Ive been consulting the last few weeks. He has studied TLG maps in serious detail and refers to them as the core nature of each lens with only minor perceptual differences regarding any applied Rx. He is also a photographer by hobby. Our main goal has been to find a PAL with as much intermediate area as possible, considering his hobby and time in front computers. OK! We discuss FF and other varieties of PALs but he is insistent on his own research. He is a nice and polite man but is only able to except hard numbers and facts to impact his opinion of the PALs he's studying and wanting to purchase. Dispensing experience and empirical data hold little value.

Case in point: He came in recently to finalize order a new set of lenses and tells me he wants a Gradal Top in 1.67 with ~ -6.00 -0.75 *** (cant remember axis) and a +1.25 ADD. There is minor difference in the eyes, maybe a half or three-quarter diopter difference total. Going into a Lindberg frame, 52 - 34 - 16 - 53. He was also considering the Ovation but based on the Plano +2.00 ADD maps the Gradal Top has the best balance of intermediate range and 'crisp and clear' distance along with near. I check the lens he has been wearing and its a Physio 1.67.

I live in a well educated and 'high-tech' region and run into this often but not to this degree. Boeing engineers, Microsoft developers, doctors and surgeons, etc. want the black and white of the situation and their questions answered but very rarely come into my office with an outside Rx from a national retail chain, their own frame, and the exact lens design and features spelled out ... then ask for our warranty/guarantee in writing before making the purchase.

Good thing our locations are so far apart or I might just be talking about my customer!

Sphinx

[DragonLensmanWV]

One thing about engineers we all know - they absolutely cannot accept the fact that the eye is possessed of variable adaptability. They can only understand hard, inflexible numbers.
I try to explain that in actuality, they are seeing me upside down,reversed and curved, according to the actual physiology of the eye that the light bouncing off me is registering on their retina.
The brain takes this strange image, flips it, reverses it, uncurves it and makes reality out of it. When you get a new Rx, the brain has to start over.

[rbaker]

One thing about engineers we all know - they absolutely cannot accept the fact that the eye is possessed of variable adaptability. They can only understand hard, inflexible numbers.

The one thing that enginers have little tolerance for is BS. They immediately recognize it when they hear it when dealing with people who are only half smart.

[AngeHamm]

The one thing that enginers have little tolerance for is BS. They immediately recognize it when they hear it when dealing with people who are only half smart.

They also tend to have extremely poor listening skills and very little ability to acknowledge the fact that someone else may have superior expertise on any subject about which they imagine themselves knowledgeable.

[Judy Canty]

Perhaps the "two week" adaptation period is linked to the experiment conducted by Stratton in the late 1800's where glasses were worn that caused the wearer to see the world "upside down". After a few days, the brain inverted the image so that everything appeared "rightside up". It took a few days for the image to invert again when the wearer discontinued using the glasses.

Just sayin'

[WFruit]

Perhaps the "two week" adaptation period is linked to the experiment conducted by Stratton in the late 1800's where glasses were worn that caused the wearer to see the world "upside down". After a few days, the brain inverted the image so that everything appeared "rightside up". It took a few days for the image to invert again when the wearer discontinued using the glasses.

Just sayin'

I actualy got to try out a similar pair glasses when I was in school for my licence. It was very strange....

http://en.wikipedia.org/wiki/Perceptual_adaptation While this article is worse than most of Wikipedia, the references sited are worth a read. Also from the Stratton experiment, it should be noted that the longer a pair of glasses is worn, no matter what the effect on the brain, the longer it will take the brain to adjust to different vision, such as that provided by a new pair of glasses.

I don't think two weeks is the guideline for how long it will take, but rather a limit on how long it should take, as most people adjust (which is more accurate than saying "adapt") to their new pair in less time than that. Two weeks is simply the limit before a patient should return to their ECP if they are still having problems.

[lind2020]

Of course..

There are lot's of optical retailers to whom the 2-week "adaptation" period is simply the best way to get you out of their store with the high hopes you won't return for a refund. The occaisional unscrupulous optician who knows that the glasses aren't made within tolerance but that you'll get used to them if you submit yourself to wearing them long enough.

There aren't a lot of those, but they're out there. We've all spent our share of time talking a presbyope off the ledge and back into a progressive successfully, two years after they last visited one of the aforementioned.

[HarryChiling]

Of course..

There are lot's of optical retailers to whom the 2-week "adaptation" period is simply the best way to get you out of their store with the high hopes you won't return for a refund. The occaisional unscrupulous optician who knows that the glasses aren't made within tolerance but that you'll get used to them if you submit yourself to wearing them long enough.

There aren't a lot of those, but they're out there. We've all spent our share of time talking a presbyope off the ledge and back into a progressive successfully, two years after they last visited one of the aforementioned.

Great post, yes we know that the eye will adapt. I would venture to say that a lot of the eyewear sold int he US could be outside of ANSI. The only real way to combat this phenomenon is to license the profession and make sure that those dispensing have the proper credentials in the first place to determine what's going to be appropriate for the "give it 2 weeks" and what's not. If a patient returns for any complaint the prudent course of action is to double check everything and call the prescriber to verify the Rx is accurate. Once evrything checks out then "2 weeks" is a small time frame to adjust compared to the amount of time the eyewear will be ultimately worn. I used to sometimes tell people that a second opinion wouldn't hurt and recommend they see their prescriber if it was an outside Rx or schedule a recheck in two weeks if they are still having an issue. Giving the patient an avenue to correct the problem if they don't adjust is often times a comfort in their minds and an opportunity in mine to maintain the patients trust.

[Barry Santini]

The only problem I see with isolating an emphasis on ANSI compliance is that refractions (ah hem...which are already done by licensed and certified and educated professionals) are at least FOUR TIMES greater in average variation for a single individual on a given day that ANSI tolerances are for fabrication.

?????

B

[Diopterman]

Barry, Barry, Barry..........,

I wish I could follow your logic, your hypothesis, your rhetoric, and total distrust of findings from any given eye exam, but sadly, I am at a total loss. I admit that I am not the brightest star in the sky, but your views are hard to follow, let alone believe.

I find myself eager to engage you in discussion, but fear that I will not get reimbursed when you use my discussion in your next RAGMAG article!

[Barry Santini]

Diopterman

Let's talk.

I receive daily some of the worst refractions you have ever seen. Maybe its a LI thing.

But I suspect it isn't.

It's rushed medical vision care. And Techs that are less than fully skilled.

So I approach every Rx with suspicion. And I feel most should too.

Feel free to disagree. I can actually see the point of feeling that an ECPs self worth is tied up in his gatekeeping.

My gatekeeping is simply applied differently. The Rx primarily. The eyewear secondarily.

I hope we can meet in person one day soon.

Barry