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  1. Replies
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    yes and no

    Although the tint I use is very specific and designed for myself, there are some filters that are better than others for most people - expect to see them within a year. (they do work really well -...
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    colour and epilepsy

    Light triggers for photosensitive epilepsy are

    Flicker - frequency and modulation (may be introduced unwittingly e.g. in France tree planting at regular intervals along roadsides have caused...
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    should tints be used

    Visual responses in low illuminance are not as simple as just increasing lens transmission. It affects Rx (usually a myopic shift - although some people become hyperopic), magnocellular processing,...
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    lundy loops

    In a small number of cases of dystonia - a similar type of sprung ptosis attachment is still used - the Lundy loop

    Haven't done one for years though
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    anisokonia

    I'd bet they haven't used eikonometry to determine whether it would help.
    But yes as its prescribed - so it has to be sorted.

    Image sizes and mapping are complex - I'd bet on the prescriber not...
  6. Replies
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    theory or practice

    Not much point sorting out anisokonia unless symptomatic. If symptomatic then you have to get mapping right - and it is often different to theoretical size differnces. It is likely that there may be...
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    OK, suggested training in filter prescribing

    A UK uni has asked me to write a post grad course for optical professionals in prescribing tints and filters. It would take 120 hours - so is unlikely to be practical for those in practice.
    ...
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    just a mar

    Whilst improving transmission on a lens is usually a good idea, using a MAR coating for some patients can be extremely bad practice if they have a problem with stimulus. An optician should be able to...
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    tint

    The fact is - there is no best tint empirically - but there will be a best tint for a given person, with a given screen, under a particular lighting condition.

    It easier to change the screen....
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    visual processing in autism

    I have put a short video on youtube that may surprise and interest optical professionals

    http://www.youtube.com/watch?v=Znu3kbPELX8

    It is just a start - but a necessary one
  11. night driving

    When assessing optimum night driving performance there are many factors to take into account.

    These include cone cell performance and how it imapcts Rx and VA
    (yes the Rx does change - the...
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    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...
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    techniques for assing filters

    happy to help - send me (privately your email address)

    I am speaking in the USA 24 July (chicago area - st charles) on the effects of filters on prosopagnosia and metamorphopsia. These common...
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    trial is a poor method

    As I work a lot of my life in colour space and am aware of its physiological effects on me and other patients, I would suggest that my personal experience with any lens is irrelevant.
    To prescribe...
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    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...
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    website not informative

    The information on the tints suggest to me that the lens is a blue blocker - but there is no technical info that I could find and this may be an incorrect assumption. Whilst there is merit in this -...
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    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...
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    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...
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    design a dichroic filter

    There are programmes that will allow the design of a dichroic filter - but empirical prescribing for special purposes may be a problem.
  20. Thread: Prism

    by Ian Jordan
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    yoked prism

    prism not only changes position, it also has a small effect on image size orientation.
    Therefore visio spatial awareness can be modified and it can be of use in numerous conditions
    google Kaplan...
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    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...
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    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...
  23. filters - differences

    Overlays have so many things wrong with them at a professional level that I would consider them unacceptable even bearing in mind that they can help some children

    Irlen uses essentially a trial...
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    prescribing for night / illumination control

    We have an instrument that can determine the effects of illumination and filters. The results we achieve would shock most optometrists.
    In many cases illumination control has more of an effect than...
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    Not an optometric problem

    The symptoms are consistent with a visual processing disorder.
    We have a specialist practice in the UK which specialises in these difficulties - they are causative in many optical conditions which...
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