Optically superior decentered over-the-counter sunglasses

Details Optically superior decentered over-the-counter sunglasses Optically superior decentered over-the-counter sunglasses

1999-10-26

2001-07-24

Sugarman, Scott J. (Department: 2873)

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

Ophthalmic lenses or blanks

C351S041000, C351S044000, C351S159000

Reexamination Certificate

active

06264327

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to eyeglasses, and more particularly to over-the-counter sunglasses of the variety that wrap around the face which include lenses that use small amounts of negative lens power and decentered optical centers to reduce optical distortion and thereby enhance vision.
BACKGROUND OF THE INVENTION
It is well,known that whenever the amount of light entering the eye is reduced, the eye pupil dilates. Such dilation occurs when an individual enters into a dark room, and to a lesser extent when sunglasses are worn. In most people, when the pupil is dilated, the eye exhibits natural spherical aberration and reduced vision. Spherical aberration is caused by those light rays entering the periphery of the dilated pupil which otherwise do not enter the pupil when the same is constricted. When the pupil is dilated, these peripheral light rays focus too rapidly in a position which is often located in front of the retina, thus creating a condition of slight myopia (nearsightedness) and reducing distance vision. Individuals who have undergone refractive surgery such as radial keratotomy or excimer laser keratotomy typically experience an increased amount of spherical aberration as a result of the surgery and generally complain that they do not see well at night or when wearing sunglasses.
In recent years, improvements have been made in filtering harmful light rays by contouring sunglasses in a manner wherein they wrap around the wearer's face. Such wrapping places the protective lenses of the sunglasses closer to the wearer's eyes, particularly temporally, and reduces the amount of peripheral unfiltered light which enters the eyes. The increasing popularity of wrap around sunglasses is not only attributable to the greater shielding of the eyes they provide, but to their styling and the athletic image connoted thereby.
Though wrapping sunglasses about the wearer's face enhances peripheral vision and provides better side protection to the eyes, such wrapping creates optical distortion referred to as base-out prism. It has been found that increased amounts of unwanted base-out prism are induced when the lenses of the wrap around sunglasses have steeper lens curves and higher refractive indexes.
The present invention overcomes the above-described deficiencies of prior art wrap around sunglasses. In accordance with the present invention, there is provided wrap around sunglasses which include lenses having a small amount of negative lens power to decrease spherical aberration caused by the sunglasses. The sunglasses of the present invention are configured such that these negative powered lenses are provided with optical centers which are decentered temporally for purposes of inducing base-in prism that neutralizes the wrap induced base-out prism. Importantly, the small amount of negative lens power provided in the lenses is within the lens power tolerance of the American National Standards Institute for over-the-counter sunglasses.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided optically superior eyeglasses (e.g., sunglasses) of the wrap around variety which are intended for sale in the over-the-counter market. The eyeglasses of the present invention comprise a frame and a pair of eyeglass lenses which are attached to the frame so as to be positionable over respective ones of the wearer's eyes, i.e., in the paths of the wearer's normal lines of sight. Each of the lenses defines an optical center and includes a spherical and convex front surface which is of a first radius of curvature. In addition to the convex front surface, each of the lenses includes a spherical and concave back surface which is of a second radius of curvature less than the first radius of curvature. This difference in the radius of curvature between the front and back surfaces of the lens causes the same to be thicker at its peripheral edge than at its center, thus imparting a negative power thereto. The optical center of the lens is defined at the thinnest portion thereof.
In the present eyeglasses, each of the lenses is preferably provided with a negative power in the range of about −0.12 to −0.25 diopters, and most preferably about −0.25 diopters. Additionally, each of the lenses is preferably tinted, with the preferred tinting being adapted to block 100% ultraviolet A and 100% ultraviolet B, plus 100% of those visible wavelengths of approximately 380 nanometers through 450 nanometers. The preferred tinting allows 10% light transmission at 475 nanometers and 20% light transmission at 500 nanometers. The preferred tint blocks 80% of the total visual light spectrum. Additionally, each of the lenses may be cut from a lens blank, or alternatively formed directly into its final configuration through the use of an injection molding technique.
In the sunglasses constructed in accordance with the present invention, the frame is sized and configured such that when positioned upon the wearer's head, the lenses are supported thereby (i.e., oriented on the head of the wearer) in a manner wherein the normal line of sight of each of the wearer's eyes crosses the back surface of a respective one of the lenses at a selected angle of wrap and at a location nasal to the optical center thereof. In the present eyeglasses, the preferred wrap angle is greater than about 95 degrees, and most preferably within the range of about 100 to 120 degrees. Additionally, the line of sight of each of the wearer's eyes preferably crosses the back surface of a respective one of the −0.25 diopter powered lenses at a distance of about 1.0 cm nasal to the optical center of the lens. By temporally decentering and providing a negative power to the lenses of the present eyeglasses, a base-in prism effect is created which neutralizes the base-out prism induced by the wrapping of the lenses and resultant passage of the wearer's normal lines of sight therethrough at angles other than perpendicular, i.e., 90 degrees. The amount of base-in prism that is created is dependent upon the negative power of the lenses and the distance the wearer's lines of sight are nasal to the optical centers thereof.
It is contemplated that the eyeglasses constructed in accordance with the present invention need not necessarily include the frame. In this respect, ear stems may be attached directly to the lenses which are sized and spaced relative to each other so as to assume orientations relative to the wearer's normal lines of sight resulting in the desired temporal decentering thereof.


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