APPARATUS AND METHOD FOR AVOIDING OCULAR MUSCULAR FATIGUE

Abstract: The present invention provides an apparatus and method for avoiding ocular muscular fatigue, the apparatus comprising a binocular light converging means (12, 14) for converging incident light (18, 20), thereby reducing ocular convergence demand when the apparatus is worn by a user. In a preferred embodiment, the binocular light converging means comprises a pair of lenses.

Description: APPARATUS AND METHOD FOR AVOIDING OCULAR MUSCULAR FATIGUE The present invention relates to an apparatus and method for the reduction or avoidance of muscular fatigue of the eyes, and is of particular but not exclusive application in avoiding such muscular fatigue encountered during prolonged reading or close use of equipment such as computers . Existing apparatus for reducing the ill effects to the eyes of prolonged reading or use of computers, or of other activities requiring the intensive, close use of the eyes, include non-prescription spectacles with colour lenses to act as filters 1) to reduce the glare from a surrounding light source and reflection from the surface on which the eyes are focussed, and/or 2) to enhance the contrast sensitivity of the print or material being focussed upon (generally by means of a yellow filter) . Other apparatus can be used to magnify the image on a computer screen, thereby reducing the degree to which a user's eyes must focus small images. Such apparatus may employ 1) one or more Fresnel lenses, and/or 2) low plus lenses which also have magnifying effect, usually ranging from +0.50 to +0.75 spherical dioptre power. It is an object of the present invention to provide an apparatus and method for reducing or avoiding ocular muscular fatigue in such circumstances . According to a first broad aspect of the present invention there is provided an apparatus for avoiding ocular muscular fatigue comprising: a binocular light converging means for converging incident light, thereby reducing ocular convergence demand when the apparatus is worn by a user. Thus, the extent to which the eyes of a user of a computer or reader of any text material must converge owing to the proximity of that computer or other text material (or other apparatus) is reduced by the apparatus according to the present invention, which performs part or much of the required convergence by means of refraction. The eyes of the user may thereby be directed generally forward and parallel, even though the user is reading material or operating a computer or other apparatus whose proximity would normally require a convergence of as much as 15° or more. Preferably the binocular light converging means is integral . Thus, the binocular light converging means may comprise a pair of optical elements (such as lenses) but these are preferably formed integrally. Preferably the binocular light converging means is of polycarbonate, acrylic or some other polymeric plastic material . Although the, for example, lenses may be made glass, it would generally be cheaper and more convenient to construct them from a plastic material, which will also be less vulnerable to breakage. Preferably the binocular light converging means is a magnifying binocular light converging means. Thus, the apparatus, in addition to reducing the required ocular convergence, may also magnify the user's view. Preferably the binocular light converging means includes or is additionally at least one colour filter. Preferably the at least one colour filter reduces the intensity of transmitted yellow light. Thus, any benefits of reducing particular colour intensities may be combined with those of the convergence according to the present invention. Preferably the binocular light converging means is provided in the form of a pair of optical elements and the apparatus includes adjustment means whereby the separation of the optical elements may be adjusted according to pupil separation of a user. Thus, the apparatus may be adjusted so that the optical elements are positioned accurately relative to each eye of a user. Preferably the light converging means comprises two lenses. Thus, although the light converging means are preferably lenses, any suitable alternative may be employed, including prisms . Preferably each of the lenses comprises an optical wedge with a base, wherein the bases of the lenses are adjacent thereby forming base-in prisms. Preferably the optical wedges are spherical optical wedges. Thus, the lenses are preferably formed from blanks of spherical form, but thicker at one extremity relative to the other to provide the properties of an optical wedge. Preferably the lenses are 0.20 to 10 base lenses, more preferably 0.25 to 1.5 base lenses, and still more preferably approximately 0.5 base lenses. Thus, lenses of higher base may be used but in normal use 2 or 3 base lenses may provide excessive convergence. Preferably the lenses are additionally prescription lenses. Thus, the convergence effect of the apparatus according to the present invention may be combined with a corrective prescription to provide prescription glasses that also provide the convergence according to the present invention. Preferably the lenses are provided as a pair of spectacles. According to a second broad aspect of the present invention there is provided a method for reducing ocular muscular fatigue due to convergence demand comprising converging light prior to the light's incidence on a user's eyes. Preferably the light is converged by means of a pair of optical elements. Preferably the optical elements are integral with each other. Preferably the optical elements are of a polycarbonate or other polymeric plastic material. Preferably the optical elements are magnifying optical elements . Preferably the light is converged by means of two lenses. Preferably each of the lenses comprises an optical wedge with a base, wherein the bases of the lenses are adjacent thereby forming base-in prisms. Preferably the optical wedges are spherical optical wedges, Preferably the lenses are 0.20 to 10 base lenses. Preferably the lenses are 0.25 to 1.5 base lenses. Preferably the lenses are approximately 0.5 base lenses . Preferably the lenses are additionally prescription lenses Preferably the optical elements are additionally colour filters. Preferably the optical elements reduce the intensity of transmitted yellow light. Preferably the method includes adjusting the separation of the optical elements according to pupil separation of a user. Preferably the optical elements are provided as a pair of spectacles . It should be noted that the convergence of light produced by the apparatus or method according to the present invention will reduce the convergence demand on the user's eyes and thereby increase the divergence of the users eyes The present invention also provides a pair of spectacles for avoiding ocular muscular fatigue comprising: a pair of convergent lenses for converging incident light, thereby reducing ocular convergence demand when the spectacles are worn by a user. Preferably each of the lenses comprises an optical wedge with a base, wherein the bases of the lenses are adjacent thereby forming base-in prisms. Preferably the optical wedges are spherical optical wedges Preferably the lenses are 0.20 to 10 base lenses, more preferably 0.25 to 1.5 base lenses and still more preferably approximately 0.5 base lenses . Preferably the lenses are integral with each other. Preferably the lenses are magnifying lenses . Preferably the spectacles are additionally prescription spectacles. Preferably the spectacles include, or the lenses additionally comprise, one or more colour filters, and preferably the one or more colour filters reduce the intensity of transmitted yellow light. Preferably the spectacles are provided with adjustment means whereby the lenses ' separation may be adjusted according to pupil separation of a user. Preferred embodiments of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a view of a pair of spectacles in accordance a preferred embodiment of the present invention; Figure 2 is a cross-sectional view through II- I of Figure 1; Figure 3 is a view of a pair of spectacles according to a further embodiment of the present invention; and Figure 4 is a cross-section through IV-IV in Figure 3. A pair of spectacles according to a preferred embodiment of the present invention is shown generally at 10 in Figure 1. The spectacles 10 have right and left lenses 12 and 14 respectively. Lenses 12 and 14 are polycarbonate or acrylic 0.5 base-in prismatic lenses (of zero spherical power, that is, so-called piano lenses) . Figure 2 is a view of cross-section II-II in Figure 1, together with ray tracings for a light source 16. Rays 18 and 20 diverging from light source 16 will, after impinging upon lenses 12 and 14 respectively, be refracted convergently, and emerge at 18a and 20b substantially parallel. Thus, when the spectacles 10 are worn by a user, who may be reading from a book or a computer monitor, or manipulating some apparatus at close proximity, the degree of convergence required by that proximity is reduced or in some cases substantially eliminated. Consequently, the muscular effort required to maintain this convergence is correspondingly reduced or eliminated, and the resultant muscular fatigue avoided. Lenses 12 and 14 have, in this embodiment, a negligible magnifying effect. Thus, the spectacles 10 reduce the convergence demand on the user's eyes, without otherwise substantially altering the user's vision. A pair of spectacles according to an alternative embodiment of the present invention is shown generally at 30 in Figure 3. In this figure, only the lens portion of the spectacles is illustrated. Lenses 32 and 34 are formed integrally for reasons of manufacturing convenience. However, as can be seen in Figure 4, which is a cross-section through IV-IV in Figure 3, lenses 32 and 34 are again base-in prismatic lenses, though formed within peripheral fabric 36, integral with lenses 32 and 34, which provides and forms the equivalent of the spectacles ' frame and nose bridge . As with the first embodiment, light from light source 38 (for example rays 40 and 42) are converged by means of refraction within lenses 32 and 34 to be substantially parallel at 40a and 42a. In practice, the peripheral fabric 36 may either conform to the spherical geometry of lenses 32 and 34, or be shaped to provide a more comfortable or aesthetically pleasing appearance. In this latter case, it may be desirable to provide peripheral fabric 36 with an opaque mask or substantially opaque colour so that light impinging upon peripheral fabric 36 will not distort or blur the image presented to the user. Modifications within the spirit and scope of the invention may readily be effected by persons skilled in the art. For example, spectacles according to the present invention may be provided with an adjustable bridge so that the distance between the two lenses is adjustable, to conform to the pupil separation of the user. Further, the lenses may be coloured to remove to some extent or completely certain colours that are thought to contribute to eye strain. Alternatively, the lenses may be somewhat modified to provide some magnification for greater ease of viewing or may superimpose a user's spectacles' prescription on the optical wedge so that other defects of vision of the user may be corrected with the reduction in convergence demand. Accordingly, it is to be understood that this invention is not limited to the particular embodiments described by way of example hereinabove.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. An apparatus for avoiding ocular muscular fatigue comprising: a binocular light converging means for converging incident light, thereby reducing ocular convergence demand when said apparatus is worn by a user. 2. An apparatus as claimed in claim 1, wherein binocular light converging means is integral. 3. An apparatus as claimed in either claim 1 or 2, wherein said binocular light converging means is of polycarbonate, acrylic or some other polymeric plastic material. 4. An apparatus as claimed in any one of the preceding claims, wherein said binocular light converging means is a magnifying binocular light converging means. 5. An apparatus as claimed in any one of the preceding claims, wherein said binocular light converging means includes or is additionally at least one colour filter. 6. An apparatus as claimed in claim 5, wherein said at least one colour filter reduces the intensity of transmitted yellow light. 7. An apparatus as claimed in any one of the preceding claims, wherein said binocular light converging means is provided in the form of a pair of optical elements and said apparatus includes adjustment means whereby the separation of the optical elements may be adjusted according to pupil separation of a user. 8. An apparatus as claimed in any one of the preceding claims, wherein said light converging means comprises two lenses . 9. An apparatus as claimed in claim 8, wherein each of said lenses comprises an optical wedge with a base, wherein said bases of said lenses are adjacent thereby forming base-in prisms. 10. An apparatus as claimed in claim 9, wherein said optical wedges are spherical optical wedges. 11. An apparatus as claimed in any one of claims 8 to 10, wherein said lenses are 0.20 to 10 base lenses. 12. An apparatus as claimed in claim 11, wherein said lenses are 0.25 to 1.5 base lenses. 13. An apparatus as claimed in claim 12, wherein said lenses are approximately 0.5 base lenses . 14. An apparatus as claimed in any one of claims 8 to 13, wherein said lenses are additionally prescription lenses. 15. An apparatus as claimed in any one of claims 8 to 14, wherein the lenses are provided as a pair of spectacles. 16. A method for reducing ocular muscular fatigue due to convergence demand comprising converging light prior to said light's incidence on a user's eyes. 17. A method as claimed in claim 16, wherein said light is converged by means of a pair of optical elements. 18. A method as claimed in claim 17, wherein said optical elements are integral with each other. 19. A method as claimed in either claim 17 or 18, wherein said optical elements are of a polycarbonate or other polymeric plastic material. 20. A method as claimed in any one of claims 17 to 19, wherein said optical elements are magnifying optical elements . 21. A method as claimed in any one of claims 17 to 20, wherein said optical elements are a pair of lenses. 22. A method as claimed in claim 21, wherein each of said lenses comprises an optical wedge with a base, wherein said bases of said lenses are adjacent thereby forming base-in prisms . 23. A method as claimed in claim 22, wherein said optical wedges are spherical optical wedges. 24. A method as claimed in any one of claims 21 to 23, wherein said lenses are 0.20 to 10 base lenses. 25. A method as claimed in claim 24, wherein said lenses are 0.25 to 1.5 base lenses. 26. A method as claimed in claim 25, wherein said lenses are approximately 0.5 base lenses . 27. A method as claimed in any one of claims 21 to 26, wherein said lenses are additionally prescription lenses. 28. A method as claimed in any one of claims 17 to 27, wherein said optical elements are additionally colour filters. 29. A method as claimed in claim 28, wherein said optical elements reduce the intensity of transmitted yellow light. 30. A method as claimed in any one of claims 17 to 29, wherein the method includes adjusting the separation of the optical elements according to pupil separation of a user. 31. A method as claimed in any one of claims 17 to 30, wherein the optical elements are provided as a pair of spectacles. 32. A pair of spectacles for avoiding ocular muscular fatigue comprising: a pair of convergent lenses for converging incident light, thereby reducing ocular convergence demand when said spectacles are worn by a user. 33. A pair of spectacles as claimed in claim 32, wherein each of said lenses comprises an optical wedge with a base, wherein said bases of said lenses are adjacent thereby forming base-in prisms. 34. A pair of spectacles as claimed in claim 33, wherein said optical wedges are spherical optical wedges. 35. A pair of spectacles as claimed in any one of claims 32 to 34, wherein said lenses are 0.20 to 10 base lenses. 36. A pair of spectacles as claimed in claim 35, wherein said lenses are 0.25 to 1.5 base lenses. 37. A pair of spectacles as claimed in claim 36, wherein said lenses approximately 0.5 base lenses . 38. A pair of spectacles as claimed in any one of claims 32 to 37, wherein said lenses are integral with each other. 39. A pair of spectacles as claimed in any one of claims 32 to 38, wherein said lenses are magnifying lenses. 40. A pair of spectacles as claimed in any one of claims 32 to 39, wherein said spectacles are additionally prescription spectacles . 41. A pair of spectacles as claimed in any one of claims 32 to 40, wherein spectacles include, or said lenses additionally comprise, one or more colour filters. 42. A pair of spectacles as claimed in claim 41, wherein said one or more colour filters reduce the intensity of transmitted yellow light . 43. A pair of spectacles as claimed in any one of claims 32 to 42, wherein the spectacles are provided with adjustment means whereby the lenses' separation may be adjusted according to pupil separation of a user.

Inventors: LEE HENRI KWOK-WAI, LEE, HENRI, KWOK-WAI
Applicants: LEE HENRI KWOK WAI, POSITIVE PLAN PTY LTD, LEE, HENRI, KWOK-WAI, POSITIVE PLAN PTY LTD.
Application year: 1999
Main classification: G02B27
IPC codes: A61F9, G02B27, G02C1, G02C7