Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1996-05-01
1998-06-30
Epps, Georgia Y.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
351162, 351163, 351213, 351219, 623 6, G02C 702
Patent
active
057742022
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a method and means for improving or modifying color vision, and a method for making the optical means.
BACKGROUND ART
The human eye is able to detect electromagnetic radiation in the wavelength range of visible light which extends approx. from 380 nm to 780 nm. The light efficiency of human vision in dependence of wavelength is defined by the so-called visibility curve. In the human eye there are three orthochromatic receptors (pigments) assuring color vision, called protos, which is sensitive to red, deuteros, which is sensitive to green, and tritos, which is sensitive to violet. Sensation of the yellow color is aroused by simultaneous stimuli of the protos and the deuteros. Simultaneous stimuli of the tritos and the deuteros causes the vision of the color turquoise, while simultaneous stimuli of the tritos and the protos leads to the sensation of the color purple. Other transitional shades of colors are produced by simultaneous stimuli of the three receptors with different intensities.
Diagrams of spectral sensitivity of the protos, the deuteros and the tritos for people having normal (average) colour vision are well known. FIG. 1 illustrates the visibility curve V(.lambda.) for normal human eye and the sensitivity curves P(.lambda.), D(.lambda.) and T(.lambda.) of protos, deuteros and tritos, respectively, for normal human color vision.
The spectral sensitivities of receptors in the eye can be determined by individual measurements (W. B. Marks, W. H. Dobbelle, E. F. Mac Nichol: Visual Pigments of Single Primate Cones, Science, Vol. 143, March 1964). Rushton performed microspectrographic measurements on eyes of living human beings and monkeys (Rushton: Visual Pigments and Color Blindness, Scientific American, March 1975). In the microspectrographic method, a thin monochromatic light beam is imaged on the retina through the pupil of the eye to be tested, the size of the light beam--when reaching the retina--does not exceed that of each receptor (protos, deuteros, tritos). The intensity of the light beam is continuously measured prior to emission and also after being reflected from the receptor. The difference of the two corresponds to the intensity of light absorbed by the given receptor, which is characteristic of the receptor's sensitivity in the given wavelength. By altering the wavelength of the testing light beam, the spectral sensitivity curve of the given receptor can be determined (Leo M. Hurvich: Color Vision, Sinauer Associates Inc., Sunderland, Mass., U.S.A., 1981, pp. 121-122).
There is another method for determining the spectral sensitivity curves of receptors by a mathematical method from results of color mixing measurements (K. Wenzel and G. Szasz: Numerical method for determining simultaneous functions having been measured with an indirect measuring method (in Hungarian), Finommechanika-Mikrotechnika, 1985, Vol. 24, No. 8/9, pp. 250-252). Results obtained by this computing method are in agreement with the results of said microspectrographic measurements.
It is well known that people do not have exactly the same color vision. So, e.g. the so-called color blind people see only two basic colors instead of three. If there is a lack of protos receptors, the color blind person is called protanop, in lack of deuteros receptors, we speak about a deuteranop person, and if tritos receptors are missing, the person is called tritanop. Additionally, people with anomalous color vision are also known, and although they have all the three receptors, they see the colors in a different way than normal people. The most frequent form of anomalous color vision appears as red-green parachromatism. People suffering in red-green parachromatism do not recognize pseudoisochromatic tables (known in practice as dotted figures) and they are not able to distinguish between red, yellow and green signals used in traffic control. Different types of parachromatism are described on pages 222 to 269 in the textbook of Leo M. Hurvich quoted above.
Anomalous color vision is an inher
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Abraham Gyorgy
Szappanos Janos
Wenzel Guttfriedne
Coloryte Hungary Optikai Kutato, Fejleszto es Gyarto Reszvenytar
Epps Georgia Y.
Schwartz Jordan M.
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