Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2000-10-30
2004-01-27
Schwartz, Jordan M. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S044000, C351S158000, C351S159000, C351S174000
Reexamination Certificate
active
06682193
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to improved ophthalmic lens elements and eyewear, including prescription lenses, spectacles, sunglasses, laser protective eyewear, and frames, coatings and edgings therefor.
BACKGROUND
Most conventional prescription lenses have relatively flat base curves. Such lenses provide a limited field of view due to peripheral distortion and/or physical size limitations. Their relatively flat shapes limit the amount of eye protection afforded by the lenses, particularly near the temples.
Wrap-around eyewear has been developed in an attempt to provide wider fields of view and greater eye protection. Wrap-around design also permits different and sometimes striking overall styles for the eyewear. However, wrap-around eyewear is typically non-prescription. These products also typically have flat base curves between 6 and 10 D. Wrap (and sometimes rake) are achieved by rotating and/or translating the optical axes of the lens in the as worn orientation. See e.g. U.S. Pat. No. 1,741,536 to Rayton; U.S. Pat. No. 5,689,323 to Houston et al. This causes the line of sight of the wearer to deviate from the optical axis, and optical performance is often significantly degraded. Peripheral vision is typically poor.
Early in the history of ophthalmic science, steeply curved prescription lenses had been described, although not as vehicles for providing greater field of view or eye protection. A relationship between curvature and through power is shown in the so-called “Tscherning's” ellipse. First described nearly 100 years ago, it attempts to identify combinations of lens curvature and lens power which have minimum abberation. The general form of the Tscherning ellipse is shown in FIG.
1
.
FIG. 1
is given for assumed typical values for lens parameters such as index of refraction, vertex distance, lens thickness, etc. The Tscherning ellipse retains its ellipsoid shape and inclined orientation for various assumed values of lens parameters, while the precise location of points on the ellipse may change. The ellipse of
FIG. 1
is derived from the corrected von Rohr equation (after Morgan) solved for point-focal (zero astigmatism) distance vision.
The lower portion
10
of the ellipse is the so-called “Ostwalt section” which describes a selection of relatively flat front surfaces for lens powers typically used in conventional prescription ophthalmic lenses. The upper portion
12
of the curve, called the “Wollaston section”, describes much more steeply curved lenses which have never gained acceptance as lens forms, although there are historical instances of attempts to make such objects (e.g. Wollaston himself). See, M. Jalie,
The Principles of Ophthalmic Lenses
p. 464 (4
th
Ed. London, 1994). Because of difficulties in fabrication, such early lenses were probably of small aperture and, consequently, perhaps, regarded as unacceptable for cosmetic reasons and because of their limited field of view.
Modern lenses with steeply curved front spherical surfaces have been made for the treatment of aphakia (absence of the natural lens of the eye as in the case of surgical removal of the lens). The general form of these lenses is shown in FIG.
2
. See M. Jalie at p. 151. Such lenses serve essentially as an eye lens replacement and are characterized by great thickness and high plus power (greater than +5 D and typically +12 D or greater). The aperture A of these lenses are of small size e.g. 26 or 28 mm in diameter. Typically such aphakic lenses have a plano radial flange
14
.
Today, the vast majority of conventional prescription lenses are relatively flat, single vision, Ostwalt section, miniscus lenses which are glazed like window panes into flat outline spectacle frames.
Conventional Ostwalt section eyewear is sometimes covered, treated or coated to provide specific reflective or anti-reflective properties. Most familiar are sunglasses which provided with coatings for selectively blocking portions of the incident light spectra. Some such lenses are designed to create pleasing colors to an observer by selective selection or absorption of incident spectral wavelengths. Such coating may involve metallic mirror layers and/or stacks of vacuum evaporated or sputter coated metal oxides. For example, coating for sunglasses are disclosed in U.S. Pat. No. 2,758,510 to Aüwärter. As another example, certain multi-layer antireflection coatings are disclosed in U.S. Pat. No. 4,070,097 to Geller. See also U.S. Pat. Nos. 5,719,705 and 5,959,518. Conventional Ostwalt section lens are also sometimes specially coated to protect the wearer from intense ultraviolet or infrared radiation, or from laser beams.
OBJECTS AND ADVANTAGES OF THE INVENTION
Applicants have studied the properties of steeply curved lenses and considered series of lenses having commonly prescribed plus or minus through powers. Applicants observed that such lenses could, in principle, provide a wide field of view and eye protection. However, certain problems would interfere with practical implementation of such wide-field lens. Generally there are problems of fabrication and distortion, and problems of producing a range of common plus or minus power prescriptions with or without available common astigmatism correction or “cyl” prescriptions.
A more subtle problem is presented by the wide range of front surface powers which would be required to provide a range of common prescription powers. For the lens assumptions of
FIG. 1
, for example, the Wollaston section would be understood to teach a variation in front surface power of from about 15 D to about 20 D for a product line through-power range of from +5 D to −8 D. This corresponds to a variation in radius of front surface curvature of from about 29 to about 39 mm, which represents a large variation in overall size and shape for lenses large enough to provide a wide field of view. Such lens cannot be fitted like panes into a single frame size, but, in fact, each prescription itself would dictate its own specialized frame size and style. While such unique styles have value, they are incompatible with providing mass-marketed eyewear with a consistent appearance.
A broad object of the present invention is to provide ophthalmic lenses with good vision properties.
It is another object of the present invention to provide a series of steep base curve lenses which are readily manufactured and dispensed.
It is another object of the present invention to provide an ophthalmic lens having good vision properties through a wide field of view.
It is another object of the present invention to provide a steeply curved lens with reduced distortion in peripheral regions.
It is another object of the present invention to provide eyewear which affords more effective eye protection.
It is another object of the present invention to provide steeply curved lenses in common power and astigmatism prescriptions.
It is another object of the present invention to provide eyewear for steeply curved prescription lenses with a consistent appearance and frame configurations for a range of prescriptions.
Certain additional advantages may be realized through the teachings of the present invention. The increased field of view allows the making of eyewear whose temporal edge is not visible to the wearer (apparent edgelessness). The teachings of the present invention also permit reduction of magnification effects and associated distortion in some steeply curved lenses.
Other advantages involve providing the eyewear designer with options heretofore unattainable in lens having good peripheral vision properties in various prescriptions. These include the ability to use smaller outline lenses, topologically and cosmetically interesting three-dimensionally curved lens edges and spectacle rims, and edge thicknesses and surfaces which are more readily hidden from view.
Other advantages involve the provision of novel sun lenses and protective eyewear tailored to provide certain desired cosmetic properties and certain reflectance and anti-reflectance properties.
These and oth
Adams Brian
Begley Paraic
Blacker Richard Simon
Carr David Lawrence
Edwards Simon J.
Burns Doane Swecker & Mathis L.L.P.
Schwartz Jordan M.
Sola International Holdings Ltd.
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