Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1988-06-20
1990-08-28
Sugarman, Scott J.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
G02C 706
Patent
active
049520474
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Background of the Invention
The present invention relates to a progressive power ophthalmic lens hereto in the introductory part of claim 1 hereto.
2. State of the Art
Progressive power ophthalmic lenses hereto in the introductory part of patent claim 1 hereto having a surface contributing to a progressive increase in refractive power, are known, by way of illustration from the DE-A No. 28 14 916, the DE-A No. 20 44 639 or the DE-A No. 30 16 935.
An ophthalmic lens having two surfaces contributing to a progressive increase in refractive power, is described in DE-A No. 34 30 334. Specific reference is made to the latter as well as to DE-A No. 28 14 916 with regard to all terms and further state of the art not expressly mentioned herein.
Particularly in the case of progressive power ophthalmic lenses having only one surface contributing to a progressive increase in refractive power, there frequently is detraction in wearer acceptance due to the so-called progressive channel, i.e. the region in which the power increases and which is suited for distant vision, and the portion for near vision are so narrow in the prior art progressive power ophthalmic lenses that they permit no overall view of large areas without head movement.
This is irritating, by way of illustration, when working at apparatuses with display screens and having to alternately glance at the information on the display screen and at files disposed beside the screen.
SUMMARY OF THE INVENTION
The primary object of the present invention is to improve a progressive power ophthalmic lens in such a manner that, in particular, looking at different areas and, especially, adjacent areas, is possible without moving the head.
According to the present invention, the progressive power surface has or in the case of an ophthalmic lens having two surfaces contributing to increasing the refractive power both surfaces have, in addition to the actual main meridian, lines on which the surface astigmatism has a minimum local value so low that there is more than one channel of vision for seeing in an approximately vertical direction.
Remarkably, a result was that the acceptance of progressive power ophthalmic lenses is increased substantially, more particularly, when different areas have to continually be glanced at, by providing the ophthalmic lenses with several channels of vision than is the case with an ophthalmic lens having a near portion and a progressive power channel maximally extended within the framework of the theoretically feasible with respect to the surface.
Most particularly surprising was that it is possible to "accommodate", on the limited surface of an ophthalmic lens, several channels of Vision suitable for distinct vision, the overall surface of which is greater than the surface of the portion suitable for distant vision in an ophthalmic lens of conventional design, i.e. having a progressive power channel and a near portion. An inventive element is, namely, that it was recognized that Minkwitz's law is only valid for a region surrounding an umbilical line or a quasi-umbilical line and thus the width of the progression zone as well as, if necessary, the portion for near vision is limited, but that, on the other hand, Minkwitz's law does not apply to distant areas so that it is possible to arrange several regions suitable for distinct vision side by side on an ophthalmic lens.
According to a feature of the present invention, it is especially advantageous, if at least one line is provided on the nasal side as well as on the temporal side of the main meridian, forming an additional channel of vision, whereby these lines do not have to run exactly parallel to the main meridian: on the contrary it is especially advantageous if that course of the lines is "adapted" to the up-down direction of the movement of the eyeball and the lines are formed on the nasal side and on the temporal side in such a manner that they make unencumbered binocular vision possible: whereby when the eyeballs move approximately in a vertical direction, the rays
REFERENCES:
patent: 4729651 (1988-03-01), Kitani
Barth Rudolf
Pfeiffer Herbert
Optische Werke G. Rodenstock
Sugarman Scott J.
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