Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
1999-08-20
2002-04-02
Sugarman, Scott J. (Department: 2873)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C351S041000, C351S163000, C351S044000
Reexamination Certificate
active
06364481
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to improvements to lenses for use in glasses of the wrap-around or shield type, such as sun-glasses, eye protection glasses, either clear or tinted, and safety glasses. While much of the following description, and indeed the description of the examples, will refer to piano lenses, it is to be understood that the lenses of the invention may also be of the prescription type.
BACKGROUND OF THE INVENTION
Glasses of the wrap-around or shield type traditionally provide for a very wide field of vision, and thus are often the preferred choice of glasses, be they sunglasses, safety glasses, or other forms of protective glasses, for sports, eye protection and the like. It is known in the prior an to manufacture piano (non-corrective) wrap-around glasses having wrap-around segments designed to shield the eye from incident light, wind, and foreign objects in the wearers field of temporal peripheral vision. Wrap-around frames for glasses of this kind, in the absence of lenses, would permit light to enter the eye from wide angles up to about 120° from the primary line of sight. However, prior art lenses for glasses of this type compromise the field of view afforded by the frames.
It has not been possible in traditional wrap-around glasses to avoid this diminished vision in the peripheral region. Thus, traditional wrap-around glasses often give rise to a reduced awareness of objects in the wearer's field of temporal peripheral vision (as a result of a reduction in the size of that field of vision). Additionally, such traditional wrap-around glasses often at least cause displacement of objects in a wearer's field of temporal peripheral vision, thus interfering with the wearer's peripheral perception of such objects.
Furthermore, such traditional wrap-around glasses typically also exhibit a degree of off-axis blur experienced with angles of gaze away from the primary line of sight.
It is an object of the present invention to provide lenses for use in glasses of the wrap-around type, which lenses will improve the wearer's field of peripheral vision and peripheral perception of objects, the improvement seeking to restore the wearer's field of peripheral vision and perception of objects to be closer to that when glasses are not being worm. The invention also aims to provide lenses which may advantageously, and additionally, reduce the off-axis blur in the optical zone thereof.
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.
The present invention provides an optical lens element adapted for mounting in a frame of the wrap-around type, the lens element including a front and back surface capable of providing an optical zone, and a peripheral temporal zone which includes a surface correction to improve the overall field of vision of the wearer.
The optical lens element according to the present invention thus provides the wearer, in the peripheral temporal zone, with an increased awareness of objects and a substantially improved perception of the correct object location. The overall field of vision may thus increase for example by up to approximately 2.3°, where the surface correction fully compensates for prismatic errors in the peripheral temporal zone.
Preferably, the lens element in the optical zone further includes a first correction to enhance vision by reducing the off-axis blur, and/or a second correction in the optical zone to assist in ensuring that the primary line of sight is undisturbed. Both of these further preferred corrections will be described below.
The optical zone of the lens element is the zone where it is intended to provide generally clear foveal vision as the line of sight of the eye rotates about its primary (‘straight ahead’) direction, as it would during typical eye movements. In this respect, it is desirable that the optical zone will include at least those portions of the lens that are used during eye rotations of up to 50° on the temporal side, up to 45° on the nasal side, and up to 30° vertically up and down from the primary (straight ahead) line of sight, with the lens in the as-worn position.
The optical zone will preferably be piano (or of zero refractive power), and the following description of preferred embodiments of the present invention will generally only describe a piano configuration. However, it will be appreciated that the optical zone may be of a prescription power of minus or plus power. In this respect, the optical zone of the optical lens element of the present invention may generally be described as including a prescription or Rx zone. The embodiment where the optical zone is piano may then be considered as a specific case thereof (Rx of zero power). The ophthalmic lens element may thus be a piano lens (or of zero refractive power), or a lens of negative or positive refractive power.
Before turning to describe the various preferred features of the lens element of the present invention, it should also be appreciated that the term ‘optical lens element’ refers to a finished optical or ophthalmic lens, or a laminated lens formed from a pair of lens wafers which may be utilised in the formation of an optical lens product. In this respect, where the optical lens element includes an ophthalmic lens wafer, the peripheral temporal zone may be provided by the front wafer or the back wafer. The ophthalmic lens may include a spherical, aspheric, toric, atoric, surface or any combination thereof and may exhibit an astigmatic correction. Further, the optical lens element may be a single vision, bi-focal or progressive lens.
Applicants have discovered that it is possible to provide an extended field of vision in a lens of the wrap-around type, whilst permitting the lens to form an optical zone, and yet still to provide a lens which provides a shield in the area of the temples. This is achieved by having a surface correction in the peripheral temporal zone.
In relation to this surface correction, beyond the optical zone (on the peripheral temporal side of the lens element), the horizontal component of prism (as assessed normal to one of the lens surfaces) preferably varies smoothly from base-nasal values, which are characteristic of the optical zone, to base temporal values, which are characteristic of those regions of the lens element of the present invention which are used for extreme temporal peripheral vision. This is in contrast to existing piano lens elements where the prismatic power continues to increase in the base-nasal sense towards the periphery of the lens element.
The preferred nature of the surface corrections may be easily understood by defining a meridian on a lens element and referring to prism in relation to it. Thus, consider a meridian on a lens element, the meridian being horizontal when the lens element is in the as-worn position, and the meridian passing through the lens centre. Then, consider the horizontal component of prism (as measured normal to one of the lens surfaces) at points along this meridian which lie between the lens centre and the temporal limit of the frame.
Preferably, the value of this horizontal component of prism at the point of intersection of the line of sight of the wearer and the lens surface will be either near zero or in a base-nasal direction. Regardless, this prism component preferably varies continuously along the meridian, and attains a maximum value in a base-nasal direction at some point along the meridian. In the preferred form the point of maximum base-nasal prism will be at, or near, the boundary of the optical zone.
Then, as mentioned above, on the peripheral temporal side of the lens element, beyond the point of maximum base-nasal prism, the horizontal component of the prism (as measured normal to one of the lens surfaces) preferably reduces smoothly in value to at least 0.1 prism dioptre less, more preferably at least 0.25 prism dioptre less than the maximum value.
In a further preferred embodiment the horizontal c
Miller Anthony Dennis
O'Connor Kevin Douglas
Sola International Holdings Ltd.
Sugarman Scott J.
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