Single vision lenses

Details Single vision lenses Single vision lenses

1999-01-19

2002-03-26

Sugarman, Scott J. (Department: 2873)

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

Ophthalmic lenses or blanks

C351S041000, C351S177000

Reexamination Certificate

active

06361166

ABSTRACT:

The present invention relates to sunglass lenses, in particular sunglass lenses with refractive power.
It is known in the prior art to manufacture non-corrective eyeglasses such as sunglasses or protective eyeglasses having wrap-around segments designed to shield the eye from incident light, wind, and foreign objects in the temporal vision field of the wearer.
Visible light and light in the UV region may enter the eye from angles as high as 100° from the line of sight.
It has not been possible, however, in prior art sunglasses or protective eyeglasses, to provide spectacle lenses with refractive power. The radii of curvature required to provide an ophthalmic lens defining a prescription zone is such that the spectacles would produce a bug-eyed appearance, which would be cosmetically unacceptable.
Whilst attempts have been made in the prior art to provide a wrap-around sun shield over otherwise generally standard prescription eyeglasses, such products are generally cosmetically unacceptable and suffer from significant optical distortions.
It is accordingly an object of the present invention to overcome, or at least alleviate, one or more of the difficulties and deficiencies related to the prior art.
Accordingly, in a first aspect, there is provided an optical lens element including
a front and back surface capable of forming a prescription (Rx) zone; and
a peripheral temporal zone.
Applicants have discovered that it is possible to provide a sufficient area of the lens to function as a prescription zone and yet still to provide a lens which provides a shield in the area of the temples. This is achieved by having a peripheral temporal zone.
By the term “optical lens element” as used herein, we mean an optical or ophthalmic lens, semi-finished lens or lens formed from a pair of lens wafers which may be utilised in the formation of an optical lens product.
The ophthalmic lens element may be a lens of negative or positive refractive power. Where the ophthalmic lens element includes an ophthalmic lens wafer, the peripheral temporal zone may be provided by the front wafer.
The optical lens element according to the present invention may be adapted for mounting in a frame of the wrap-around or shield type.
The peripheral temporal zone may be at least in part of generally toric shape. The peripheral temporal zone may-be at least in part generally piano.
The peripheral temporal zone may itself form an extension of the prescription zone or may be a non-prescription zone.
In an alternative or additional aspect, the peripheral temporal zone may be modified to permit light control within the zone.
The lens element may be rotated temporally about a vertical axis through the optical centre thereof or the optical axis may be decentred relative to the geometric axis, or the lens element may be both rotated and decentred.
It will be understood that the peripheral temporal zone, for a typical sunglass lens element of the wrap-around type, may for example extend for approximately 10 to 25 mm.
In a further aspect of the present invention, there is provided an optical lens element providing prescription (Rx) correction generally in the range −6.0 D to +6.0 D with 0 to +3 cyl
wherein the front surface is capable of being mounted in a frame of constant design curve irrespective of the Rx, such frame curves being 5.0 D and above; and
the back surface provides good clearance from temples or eye lashes.
The ophthalmic lens element may form part of a series of lens elements, e.g. of the type described in International Patent Application PCTIEP97/00105, the entire disclosure of which is incorporated herein by reference.
Preferably the front surface is capable of being mounted in a frame of constant design curve of between 8.0 D and 9.0 D.
More preferably the front surface of the lens element has a high curve extending from nasal to temporal limits, but the vertical curve is 6.0 D or below.
It will be understood that such vertical curves permit the final prescription lenses, preferably edged lenses, to be adapted to the shape of the wearer's face and so locate closely in a form of the wrap-around type (so-called “toric” design).
Alternatively the optical lens elements may be adapted for mounting in a frame of the shield type. Accordingly in a still further aspect of the present invention there is provided a unitary optical lens including
a pair of optical lens elements, each lens element providing prescription (Rx) correction generally in the range −6.0 D to +6.0 D with 0 to +3 cyl
wherein the front surface is capable of being mounted in a frame of constant design curve irrespective of the Rx, such frame curves being 5.0 D and above; and
the back surface provides good clearance from temples or eye lashes.
Accordingly in a particularly preferred embodiment the present invention provides a spectacle frame, or a unitary lens, including a pair of optical lens elements, which lens elements provide true Rx correction in a prescription (Rx) zone for a wearer up to 50° off axis, preferably 80° off axis, and terminating in a peripheral temporal zone, that provides clear perception of objects in the peripheral area of human vision and avoids prismatic jump from the prescription zone to the peripheral temporal zone.
The optical lens element according to the present invention may, when mounted, in a spectacle frame, be rotated temporally about a vertical axis through the optical centre thereof.
Accordingly in a further aspect of the present invention, there is provided an optical lens element adapted for mounting in a frame of the wrap-around or shield type, such that the lens element is rotated temporally about a vertical axis through the optical centre thereof, the lens element including
a front and back surface capable of forming a prescription (Rx) zone; and optionally
a peripheral temporal zone;
the front and/or back surface bearing a surface correction to at least partially adjust for errors including astigmatic and power errors.
In this embodiment, whilst the optical axis continues to intersect the line of sight of the wearer, a number of optical effects and errors are thus introduced as discussed below. However, by suitable selection of the combination of front and/or back surface, the optical errors may be reduced or eliminated.
Accordingly, in a still further aspect of the present invention there is provided an optical lens element adapted for mounting in a frame of the wrap-around or shield type, the lens element including
a front and back surface capable of forming a prescription (Rx) zone; and optionally
a peripheral temporal zone wherein the optical axis is decentred relative to the geometric axis of the lens element to provide for prismatic correction,
the front and/or back surface bearing a surface correction to at least partially adjust for errors including astigmatic and power errors.
Applicants have discovered that it is possible to produce an optical lens element, preferably a sunglass lens element, which includes a prescription (Rx) zone and which is decentred to provide a prismatic correction.
Preferably the front and/or back surface of the optical lens element further includes a surface correction to at least partially adjust for prismatic errors introduced by lens tilt.
Illustrative optical effects and errors may be summarised as follows:
The effects are described by consideration of the effects seen by the wearer along the line of sight that intersects the optical axis of the lens element:
Astigmatic Error
There is an induced astigmatic error such that the astigmatism, a, is proportional to the power of the lens, P, and proportional to the square of the rotation angle of the lens.
Power Errors
When the lens is used in a wrap-around form the mean through power of the lens changes. The mean power error, dP, is proportional to the astigmatic error, a, and proportional to a constant, k, that is related to the index of the lens. Hence in a minus Rx the mean power becomes more negative and in a plus Rx the mean power becomes more positive.
Prismatic Effects
Due to

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