Method of testing and corresponding vision aid

Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Subjective type

Reexamination Certificate

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Reexamination Certificate

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06729729

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to methods of testing and/or methods of selection and/or methods of manufacture applicable to the provision of vision aids for use in optical recognition tasks including reading. A particular aspect of the invention relates to the provision of vision aids to assist in reducing the effects of dyslexia and related and other optical disorders. It is to be understood that the term vision aids includes the use of a vision aid in which the aid is provided by the use of particular calorimetric parameters in the colour of the background of a visual display unit screen.
The invention provides a new approach to the selection and/or manufacture of tinted transparent vision aids for such use.
There is disclosed in U.S. Pat. No. 4,961,640 (Irlen) a system intended for the provision of tinted spectacles which are to be worn by the user at all times during which the intended benefits are required—see column 12 at lines 21 to 23. In the system of the U.S. 640 specification the tinted spectacle elements are selected (albeit with reference to graphic data relating to the optical parameters of the spectacle elements) on the basis of data obtained by purely intuitive methods based upon the patients'own interpretation of criteria selected (see the case studies commencing at column 7 and line 30). Case 1 refers to Ann, a woman of age 21 having very detailed listed perceptual impairments. It is stated at column 8, line 1 that Ann was then diagnosed with the IVPS test attached in “Appendix 1”, on which she scored 62% affirmative responses. The U.S. 640 specification does not include an “Appendix 1” so there is no disclosure relating to this test. However, it appears from the text in column 8 that this test is purely a diagnostic test related to the diagnosis of the perceptual impairments mentioned above. It is stated that clear glass lenses having no vision correction other than their tint and optical density, taken from the lens set specified in “table 1 above” were superimposed in a lens frame . . . The pages of the U.S. 640 specification likewise do not include a “table” so it is difficult to know what this disclosure means. However, what is clear is what is stated (at column 8 at line 8) that “in the case of Anne it appeared that the symptoms stated above were minimised by superimposition for both eyes of lenses pink 2 and green 1”. It is then stated that Anne was given a conventional opthalmological examination and that (column 8, line 18) when fitted with the pink and green tinted lenses the patient reported a dramatic improvement in depth perception with clear peripheral vision. Other improvements are also noted including increased reading rate and the elimination of eye strain.
It needs to be clearly understood that the disclosure in the U.S. 640 specification in relation to Case 1 (Anne), case 2 (Betty), and Case 3 (Clio) entirely adopts the same intuitive approach to the identification of the calorimetric parameter applicable to the tinted spectacles to be used for improving vision. Thus, it is stated (column 8 at line 8) that “in the case of Ann it appeared that the symptoms described above were minimised by superimposition for both eyes of lenses pink 2 and green 1”. In other words, the tester just guessed which were the right lenses, tried them, and asked the patient how she perceived the result. The same applies to Betty and Clio. Likewise, there is no recognition in the U.S. 640 specification of the importance (or even the existence) of “colour space”. By colour space we mean (in one aspect of the invention in which the concept may be identified as “perceived colour space”) the three-dimensional concept of the three calorimetric parameters which any tinted transparent vision aid possesses, namely values with respect to hue (or frequency) and saturation (or density) and luminosity (or total light energy).
In relation to hue (or frequency) the calorimetric parameters may alternatively be identified as. “biological/physical colour space” based on values on red/green/blue scales which thus provide an alternative definition of colour space. This latter approach (red/green/blue or R/G/B values are of particular relevance in relation to the testing and use of the method of the invention in relation to VDU screens.
Additionally, the U.S. 640 specification does not recognise the significance of types of optical tasks to be undertaken by the patient being tested.
While it is not disputed that the techniques disclosed in the Irlen specification can produce worthwhile benefits in terms of enhanced interpretation of visual data, we have discovered that the benefits available from the use of tinted screen devices (whether used as overlays placed on printed text, or used in relation to VDU screens as background colour or as a front-mounted screen tint element, or even in spectacle elements) are enhanced to an extent which is generally thought somewhat unlikely when the calorimetric parameters relating to the tinted elements are determined on a quantitative basis and applied to the selection or production of the optimum tinted element for a given patient. Indeed, our data suggest that far from the perhaps expected situation of diminishing returns for increasing accuracy in screen tint selection, in fact the opposite is true and the returns for such accuracy are far from diminishing and actually disproportionate to the numerical value of the three values in colour space (as discussed elsewhere as between an ill-matched screen tint and a well-matched one.
We have also discovered that not only are quantitative tests beneficial to an unexpected extent, but also that it is most important to separate the types of optical tasks to be undertaken by the patient into array tasks (such as reading or recognising rows of data, and non-array tasks such as the searching for and eventual finding of one or more hidden items on a page of data. We have thus discovered that the difference between array and non-array includes substantial differences in the use of the muscles of the eye which leads to fundamental differences in the optical problems associated with these two types of tasks. If the two types of tasks are confused or mixed as in the prior art such as the U.S. 640 specification, the results of the tests are, we have discovered, relatively low in value.
Finally, we have also discovered that in the methods of testing applicable to the provision of tinted transparent vision aids, the provision of an optimum such aid for a given patient requires attention to the three-dimensional aspects of the calorimetric parameters, namely the three-dimensionally plotable values of hue or frequency and saturation or density and luminosity or total light energy. Unless these three values of perceived colour space (or the red/green/blue or R/G/B values of biological/physical colour space, see discussion above) are taken in to account, the calorimetric parameters of the vision aid resulting from a testing procedure can only be, at best, a very rough approximation to the optimum values needed by the patient. There is no recognition in the U.S. 640 specification of this requirement nor of the distinction between array and non-array tasks.
SUMMARY OF THE INVENTION
An object of the present invention is to provide methods of selecting and/or making and/or using vision aid devices providing improvements in relation to one or more of the matters discussed herein or improvements generally.
According to the inventor there is provided a method and apparatus as claimed.
In an embodiment of the invention the method for quantitative determination of the calorimetric parameters (in three-dimensional colour space) of the tinted screen device, which in the embodiment forms the visual aid device, comprises monitoring the response of the patient to systematic test procedures on a numerical basis and recording the resultant test data on a graphical basis. The graphically recorded data is then available for interpretation with respect to the optimum values of the calorimetric parameters, and th

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