Results 1 to 25 of 25

Thread: Tint Colour Tolerance

  1. #1
    Bad address email on file
    Join Date
    Jun 2008
    Location
    England
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    48

    Tint Colour Tolerance

    Since it is possible to measure colour coordinates for a tinted lens, I was wondering if it were possible to apply a working tolerance. This would be useful in matters of dispute with customers who claim a colour deviation.

    Does anyone do anything like this, or is life just too short?:cheers:

  2. #2
    Optimentor Diane's Avatar
    Join Date
    May 2000
    Location
    Jackson, GA - Jonesboro, GA no more
    Occupation
    Dispensing Optician
    Posts
    2,331

    The customer...

    ... may not always be right, but they ARE the customer... If they don't like it, change it...life IS too short.:)

    Diane
    Anything worth doing is worth doing well.

  3. #3
    Bad address email on file
    Join Date
    Feb 2005
    Location
    Wisconsin for now
    Occupation
    Dispensing Optician
    Posts
    78
    The answer is yes, most manufacturers set thier own standards for measurable tints, often expressed in CIE L.A.B. standard measurement. This will usually depict hue and intensity.
    As far as the actual patient, scientific measure can be skewed as to perception. Lighting makes a huge difference, where you can visually see hue difference in two lenses where the scientific measure with a standardized light source can be similar.
    For repeatability in manufacturing (and monitoring tint samples), measurement and standard setting makes sense. Dealing with patient impact can vary irregardless.

  4. #4
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Redhot Jumper

    Every tint is measurable in a spectrometer. Tint samples are usually made on regular virgin CR39 for which the are geared.

    When you start useng coated lenses the colors are changing as you are not tinting the lens anymore but the coating which is made of different materials that accept the dye differently

  5. #5
    Bad address email on file
    Join Date
    Apr 2005
    Location
    Cambridge UK
    Occupation
    Other Eyecare-Related Field
    Posts
    116

    tolerances

    There are a number of problems in this area - filter tolerances in colour space - metamerism - and physiological effects eg McAdams Ellipses

    BUT - it is something that should be standardised - the effects of filters on many optometric (and physiological) measurements can be astonishing, but so few optical professionals have the knowledge, instrumentation or training in how to prescribe.
    And the ONLY way to prescribe filters to international standards is in CIE coordinates + luminosity. The envelope in colour space should be specified and convolving for ambient lighting is essential.
    Empirical prescribing should not be undertaken by professionals - except as a protective measure. They should know the effect of the tint / filter on the individual - it is a source of shame that optical professionals often have no idea what the effects of a tint filter on the patient are in the environment in which they are to be used. And they should only prescribe when the tint is either neutral or beneficial - and be able to show how they came to that decision.
    When the public find out........

  6. #6
    Bad address email on file
    Join Date
    May 2009
    Location
    Geelong Australia
    Occupation
    Dispensing Optician
    Posts
    2

    Wave Australian Standards

    Quote Originally Posted by Ian Jordan View Post
    There are a number of problems in this area - filter tolerances in colour space - metamerism - and physiological effects eg McAdams Ellipses

    BUT - it is something that should be standardised - the effects of filters on many optometric (and physiological) measurements can be astonishing, but so few optical professionals have the knowledge, instrumentation or training in how to prescribe.
    And the ONLY way to prescribe filters to international standards is in CIE coordinates + luminosity. The envelope in colour space should be specified and convolving for ambient lighting is essential.
    Empirical prescribing should not be undertaken by professionals - except as a protective measure. They should know the effect of the tint / filter on the individual - it is a source of shame that optical professionals often have no idea what the effects of a tint filter on the patient are in the environment in which they are to be used. And they should only prescribe when the tint is either neutral or beneficial - and be able to show how they came to that decision.
    When the public find out........
    Certainly not for the faint hearted Ian
    Not sure I would just yet, like to enter a debate that might double the number of enemies I might already have.
    Australian standards don't really do much to help this debate either. Nothing empirical, instead statements such as ....."appear" to be of the same colour...,.....hue shall "appear" to be constant....and so on without any real yard stick or qualification of the viewer to refer to.
    I use and support the use of a spectrophotmeter and have occassions when the colour and depth "appear" the same but are not producing similar transmittance data.
    Would this bother the wearer?
    I can't help but wonder what we would find if we carried out spectra tests on lenses being issued for remedial purposes, namely dislexia.

  7. #7
    Banned
    Join Date
    Jun 2000
    Location
    Only City in the World built over a Volcano
    Occupation
    Dispensing Optician
    Posts
    12,996
    We'd probably find that tints for dyslexia belong with the Bates method.

  8. #8
    Bad address email on file
    Join Date
    Apr 2005
    Location
    Cambridge UK
    Occupation
    Other Eyecare-Related Field
    Posts
    116

    dyslexia - just the start of effects

    We now know of over 60 physiological effects of filters - most of which are measurable clinically eg EEGs,
    The dyslexia debate needs to be opened - but I would contend that the symptom change are consequential and are the result of measurable optometric (and other physiological) changes. Most lenses eg Irlen, Colorimeter (but NOT Orthoscopics lenses) used in dyslexia are indistinguishable from standard optometric filters. Orthoscopics lenses (which I designed because standard optometric filters were inappropraite) are very different. I am happy to discuss the differences and why - but it requires a lecture, rather than a post. Standard optometric filters will work in some cases and to some extent - but in internal trials we found that they are relatively poor for around 80% due to colour space coverage and the reactions of the LMS pathways and ganglion cell responses. Dorsal stream effects are relatively low in standard lenses - and effects such as using Orthoscopics lenses to create a vectored Pulfrich phenomenon often changes lives. But so few optical professionals have significant knowledge of psychophysics, they cannot access the strong physical responses that can be achieved (and measured).
    The DVD I have recently made with Coventry University in the UK shows a few of these effects and is a good introduction for those that do not understand even the basic effects of filters on neurological processing.

    I am speaking on a major effect of filters on the fusiform gyrus and the amygdala in the USA (St Charles Illinois) on 24 July this year - prosopagnosia and metamorphosia, measurement and management techniques. This talk is to the national conference of the Autism Society of America - a filter treatment will be demonstrated which may affect around 1% of the population (80% of those on the autistic spectrum) - an opportunity (or threat) to the optical community.

    Therefrore, I have a small window in which I would be happy to demonstrate the effects of filters to optical professionals / academics - and if required debate publicly - anyone that does NOT believe in the effects of filters particularly welcome, but be prepared to defend your position! Converts are always welcome. I would actually say that it virtually impossible for the optical professions to do a good job in 20% of cases - without taking into account visual stimulus. But ignorance is bliss. To suggest accurate filter prescribing is like using the "Bates method" shows a lack of understanding - and means that patients suffer.
    Last edited by Ian Jordan; 05-15-2009 at 02:01 AM.

  9. #9
    Bad address email on file
    Join Date
    May 2009
    Location
    Prague
    Occupation
    Optical Wholesale Lab (other positions)
    Posts
    5
    Quote Originally Posted by Diane View Post
    ... may not always be right, but they ARE the customer... If they don't like it, change it...life IS too short.:)

    Diane
    I agree with that , if the customer don't like the color we change it.

    If you talk about % of absorbtion then it is measured . If the order is for say 50% then the customer can not claim that "the color seems to be to dark." :finger:

    Paul

  10. #10
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Redhot Jumper

    Quote Originally Posted by Ian Jordan View Post

    BUT - it is something that should be standardised -

    That would be the day...............how would you accomplish standardisation ?

  11. #11
    Bad address email on file
    Join Date
    Apr 2005
    Location
    Cambridge UK
    Occupation
    Other Eyecare-Related Field
    Posts
    116

    standardisation

    I would specify as a CIE coordinate in a range of light conditions and light transmission in each of the nominated sources
    These would be (as a minimum)
    daylight - CIE standards already apply - I would use bright sunlight coordinates and also possibly cloudy day coordinates
    fluorescent - which type though ? or more than 1?
    flat - for overall transmission is essential
    other light sources eg car headlights of varying types, may also be useful and can be factored in.

    Tolerances vary depending on patient and should be based on McAdams Ellipses and where coordinates are found within colour space. It is probably best to work on a graphical tolerance base, with greater tolerance towards the green less in red and even less in blue. Absolute tolerances could be specified in both transission hue and saturation or as a colour space envelope.

    Lenses should be prescribed as an absloute colour space coordinate and then convolved for metamerism to take into account ambient lighting.
    Its a difficult one, but not insurmountable

    And until there are some standards and absolute prescribing it is impossible to prescribe tints well - the standards of tint prescribing are generally primitive in optometry / opticianry, reliance is on the empirical - not the clinical responses - and patients should expect better.

    The tolerances we work to are determined by the physiological responses of the patients - they vary from virtually no tolerance to any colour will do.
    But at least we know, and can take appropriate steps.
    And the difference is often life changing, not just in dyslexia - but there are a large number of physiological, pathological and cognitive responses that can be modified.
    And for those that have not been shown how to assess colour responses - find out!!!

  12. #12
    Banned
    Join Date
    Dec 2006
    Location
    On Top
    Occupation
    Other Eyecare-Related Field
    Posts
    1,662
    Quote Originally Posted by Falstaff View Post
    Since it is possible to measure colour coordinates for a tinted lens, I was wondering if it were possible to apply a working tolerance. This would be useful in matters of dispute with customers who claim a colour deviation.

    Does anyone do anything like this, or is life just too short?:cheers:
    Labs have been trying the tolerance thing on their customers for years. It does not work for them.

  13. #13
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Blue Jumper might Dollar........................

    Quote Originally Posted by Ian Jordan View Post
    And for those that have not been shown how to assess colour responses - find out!!!
    I would say after having seen too many post's on colored lenses, this an impossible feat here in North America where the mighty dollar in sales is more important than a fitting color effect.

  14. #14
    ATO Member HarryChiling's Avatar
    Join Date
    Apr 2005
    Location
    Nowhereville
    Occupation
    Other Eyecare-Related Field
    Posts
    7,765
    Quote Originally Posted by Chris Ryser View Post
    I would say after having seen too many post's on colored lenses, this an impossible feat here in North America where the mighty dollar in sales is more important than a fitting color effect.
    That's no longer acceptable as an excuse, as the cost for a cheap spectrometer is in the $400 price range.

    http://www.vernier.com/spectroscopy/svis.html

    Your lab should be able to take a sample lens and at least match it almost to the tee, so that shouldn't be an issue. Interesting subject I agree with the use of CIE data as a means for describing tints, but as for prescribing we are a far cry from the place where the three "O's" have much understanding of tints and their effects, at least not the majority of them.
    1st* HTML5 Tracer Software
    1st Mac Compatible Tracer Software
    1st Linux Compatible Tracer Software

    *Dave at OptiVision has a web based tracer integration package that's awesome.

  15. #15
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Blue Jumper Having paid $ 17,000 for the Cecil spectrometer.............

    Quote Originally Posted by HarryChiling View Post

    That's no longer acceptable as an excuse, as the cost for a cheap spectrometer is in the $400 price range.
    Having paid $ 17,000 for the Cecil spectrometer we use, I doubt that the price for a good UGV meter should also apply for a full fledged spectrometer until I read the last paragraph on that website:

    Note: All Vernier products are designed for educational use only. Our equipment is not designed or recommended for research or any apparatus involved with any industrial or commercial process such as life support, patient diagnosis, control of a manufacturing process, or industrial testing of any kind.

    So that would put it into the demonstration category that is of no use for any serious industrial use.

  16. #16
    ATO Member HarryChiling's Avatar
    Join Date
    Apr 2005
    Location
    Nowhereville
    Occupation
    Other Eyecare-Related Field
    Posts
    7,765
    Quote Originally Posted by Chris Ryser View Post
    Having paid $ 17,000 for the Cecil spectrometer we use, I doubt that the price for a good UGV meter should also apply for a full fledged spectrometer until I read the last paragraph on that website:

    Note: All Vernier products are designed for educational use only. Our equipment is not designed or recommended for research or any apparatus involved with any industrial or commercial process such as life support, patient diagnosis, control of a manufacturing process, or industrial testing of any kind.

    So that would put it into the demonstration category that is of no use for any serious industrial use.
    You'd be suprised the accuracy, and most of their products have that disclaimer. If the same version were to remove that label and charge $10K more for it then it wouldn't be practical. I would also have to question all the various UV meters out there being used commercially. For example:

    http://www.spectracolor.org/rgb-spect.htm
    http://www.optochemicals.com/products/info_uvmeter.htm

    You as a tint manufacturer even have a picture of your $17K spectrometer to show your commitment to QC, but there is no process in place at the level where the product gets dispensed to patients? Then you say it's because fo the cost, but you don't advocate the use of a low cost spectrometer? Chris something is better than nothing and the spectrovis is a great solution at the price and would improve the quality of tint matching 1 millions times more than it is now, considering their is no standard in place this product can be used to create ones own standard should they be interested in stepping up their game.
    1st* HTML5 Tracer Software
    1st Mac Compatible Tracer Software
    1st Linux Compatible Tracer Software

    *Dave at OptiVision has a web based tracer integration package that's awesome.

  17. #17
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Blue Jumper UV meters should be checked.................

    Quote Originally Posted by HarryChiling View Post
    I would also have to question all the various UV meters out there being used commercially. For example:

    http://www.spectracolor.org/rgb-spect.htm
    http://www.optochemicals.com/products/info_uvmeter.htm
    Actually UV meters should be questioned........................

    UV meters used widely do measure a a fixed wavelength . Some of them measure 382 nm while others measure at 400 nm (yellowish UV).

    If the UV cutoff of a lens is at 382 (clear UV) it will read on a meter that is set at 382 nm it will red full 100% absorption.............................

    while measured on an instrument set for 400 nm it will read about 70% absorbtion, which is about half way from the 365 nm every lens absorbs anyhow.

    If you don't know what your UV meter is geared for, what good is it then ?

    Read my article on the subject at: http://optochemicals.com/prism_article.htm

  18. #18
    Banned
    Join Date
    Jun 2000
    Location
    Only City in the World built over a Volcano
    Occupation
    Dispensing Optician
    Posts
    12,996

    What a UV meter is good for:

    UV meters are to convince the customer that his present glasses are not blocking UV properly and that yours do. Unless you work for NASA, mearly this and nothing more.

    Chip

  19. #19
    Bad address email on file
    Join Date
    Apr 2005
    Location
    Cambridge UK
    Occupation
    Other Eyecare-Related Field
    Posts
    116

    two types of tolerances

    Essentially there are two types of tolerances for filters, one a physiological one i.e. do filters have an effect on the person and if so what is an acceptable tolerance on optimum filter for their visual / body well being, the second is what tolerance can we expect a lab to work to.
    The first must determine the second.

    Evidence is growing that filters can have major physiological effects - it will (in time - to a resistant optical / medical community) become impossible to prescribe (or not prescribe) inaccurately and get away with it.
    I would give it 5 years - things are changing, I am going to be giving presentation in Chicago next month to a very strong lobby group on the effects of filters on prosopagnosia and metamorphopsia (at a national conference - expected attendees 3000) Once the message is out .....
    About 3 percent of patients are affected - and ignored by optometrists and ophthalmologists. Is there a serious risk of litigation in the future? Personally, I think it is inevitable

  20. #20
    ATO Member HarryChiling's Avatar
    Join Date
    Apr 2005
    Location
    Nowhereville
    Occupation
    Other Eyecare-Related Field
    Posts
    7,765
    Quote Originally Posted by Ian Jordan View Post
    Essentially there are two types of tolerances for filters, one a physiological one i.e. do filters have an effect on the person and if so what is an acceptable tolerance on optimum filter for their visual / body well being, the second is what tolerance can we expect a lab to work to.
    The first must determine the second.

    Evidence is growing that filters can have major physiological effects - it will (in time - to a resistant optical / medical community) become impossible to prescribe (or not prescribe) inaccurately and get away with it.
    I would give it 5 years - things are changing, I am going to be giving presentation in Chicago next month to a very strong lobby group on the effects of filters on prosopagnosia and metamorphopsia (at a national conference - expected attendees 3000) Once the message is out .....
    About 3 percent of patients are affected - and ignored by optometrists and ophthalmologists. Is there a serious risk of litigation in the future? Personally, I think it is inevitable
    In Pensylvania not to long ago their was a bill that was trying to get filters and tints considered a prescription option so unless the OD or OMD prescribed it the optician wouldn't be able to fit it. The bill failed horribly, I don't think sunglass manufacturers are going to let a bill like this pass and in the USA that's more important that the people.
    1st* HTML5 Tracer Software
    1st Mac Compatible Tracer Software
    1st Linux Compatible Tracer Software

    *Dave at OptiVision has a web based tracer integration package that's awesome.

  21. #21
    Bad address email on file
    Join Date
    Apr 2005
    Location
    Cambridge UK
    Occupation
    Other Eyecare-Related Field
    Posts
    116

    tint clinical effects

    When you say that the sunspec manufacturers won't allow it - that assumes that the clinical evidence is that tints have little effect.
    That is going to change - and in the relatively near future. I expect that within around 5 years that will be an untenable situation (there is a lot of research going on - we've just completed a major clinical trial at a medical school - it will be published in a year or so - the results will be world news, not just in optics - and there are a lot of other trials either planned or in progress. Some will be very damning of current prescribing techniques and it is inevitable that there will be controversy). It will be very interesting.


    It will be a bit like cigarettes - once socially acceptable and without any risks - now banned and a cancer risk. But that is in the future, it's just a matter of how long. The effects are MUCH greater than optical professionals believe. And current practices will have no option but to change considerably.

  22. #22
    Master OptiBoarder OptiBoard Silver Supporter Barry Santini's Avatar
    Join Date
    May 2000
    Location
    Seaford, NY USA
    Occupation
    Dispensing Optician
    Posts
    6,008
    The human eye is not a spectrometer. It is a very discriminating comparator, especially with respect to shades of grey.

    Specific absolute absorptions, to a 1 % tolerance is IMHO, way way way too musch precision with respect to general tinting absorbtion.

    The spectrographic breakdown, i.e., the exact percentage of individual wavelengths however, is important, especially with respect to prescribing tints. The CIE coordinates and accompanying illuminace standards are the most precise way to go here.

    Barry

  23. #23
    Rising Star
    Join Date
    Jan 2009
    Location
    munich
    Occupation
    Lens Manufacturer
    Posts
    85

    Tints - Perception, comparison and reality

    After cross reading the thread I want to come back to the original question and conclude, yes , you have to have accurate workable tolerances in your tinting departement as:

    V lambda Transmission, plus minus 2 percent is tolerable as rule of thumb, but L-R may never ever differ by the slightest margin.

    You can use color reference samples, identical sets for customers and production. Regularly checked, never displayed permanently, always in the drawer.
    Or, you can specify Color by CIE coordinates. This will cost you an arm and a leg,

    but all of this still won't help a lot in a customer argument.

    As Barry said, the human eye is an exceptionally sensitive comparator, plus color perception is individual. I might have said this in the past, but ask 10 people to adjust color on a TV set and watch. You can see color differences on samples, which turn out to be offset (spectrophotometer reading) by less than 2nm, this is close to the resolution limit of most instruments.

    Keep your experienced tinting staff loyal (they are magicians), apply good workmanship and accept that Colors & Customers are sometimes difficult.
    But it's good business after all, this is what can make you different to the 800-pound gorilla "standard colors only, take it or leave it" competitor.

    Georg Mayer
    Rodenstock Munich

  24. #24
    Bad address email on file
    Join Date
    Apr 2005
    Location
    Cambridge UK
    Occupation
    Other Eyecare-Related Field
    Posts
    116

    cie coordinates or lambda?

    whilst spectrometer readings are important from the point of view of the lab, we use cie coordinates as the only absolute technique for prescribing filters as metamermism can be factored in.

    how do filters affect people?

    if they don't affect people to any great extent then tolerances are relatively unimportant - however, the greater effect stimulus input has on the physiology, optometry,cognition and medical responses, the greater the need for accuracy. This has to take into account ambient lighting and filter transmission. It would be extremely difficult (perhaps impossible) to achieve this using transmission data - and whilst i accept that using cie coordinates is complex, it is essential.

    The debate about the effect of filters will open soon

  25. #25
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Redhot Jumper The debate about the effect of filters will open soon...........

    Quote Originally Posted by Ian Jordan View Post

    The debate about the effect of filters will open soon

    That will be interesting................in the meantime there is very little talk about it.

    In Europe opticians do not tint, they le\ty all the lab do it. In North America most of them have a little corner in the back whith a steaming tinting yacky unit that emits hot glycol ether or ethylene fumes from the neutralizer to be inhaled by everybody, Employees as well as patients.

    Most of them do not even have a ventilation hood sending the fumes to the outside.

    effects of acute exposure
    effects of chrionic exposure

    also , in a preliminay studyto assess the effects of exposure of pregnant rats and mice to aeosols at concentrations 150, 1000, and 2500 mg/m3 for 6 hours a day throughout the period of organogenesis, teratogenic effects were produced at the highest concentration, but only in mice. the conditions of these latter experiments did notallow a cnclusion as to wehther the developmental toxicity was mediated by inhalation of aerosol, percutaneous absorbtion of ethylene glycol from hogh aerosol concentrations by whole-body or nose-only exposure, it was shown that nose-only exposure resulted in maternal toxicity (1000 and 2500 mg/m3), and developmental toxicity with minimal evidence of teratogenicity (2500 mg/m3) in ................................

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Change of lens colour after DIPCOAT
    By Claudia in forum Ophthalmic Optics
    Replies: 4
    Last Post: 08-19-2008, 04:56 AM
  2. Colour Problems
    By au in forum General Optics and Eyecare Discussion Forum
    Replies: 3
    Last Post: 05-21-2008, 08:26 AM
  3. Cheating colour blindness?
    By MHodal in forum General Optics and Eyecare Discussion Forum
    Replies: 18
    Last Post: 07-15-2006, 10:26 AM
  4. Colour Overlays for Dyslexia
    By sarahr in forum General Optics and Eyecare Discussion Forum
    Replies: 13
    Last Post: 04-04-2005, 03:03 PM
  5. Pete's BumbleBee... the colour scheme you've GOT to see!
    By Pete Hanlin in forum Just Conversation
    Replies: 3
    Last Post: 06-20-2001, 08:53 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •