Patent Publication Number: US-8534830-B2

Title: Eyeglass with enhanced ballistic resistance

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/648,232, filed on Dec. 28, 2009, which claims the benefit of U.S. Provisional Application Nos. 61/143,645, filed Jan. 9, 2009, and 61/266,804, filed on Dec. 4, 2009, the entireties of both of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Inventions 
     The present inventions relate generally to mounting systems for eyewear, and more specifically to methods and apparatuses for mounting an optical lens in a manner that provides excellent ballistic resistance and lens stability. 
     2. Description of the Related Art 
     A wide variety of improvements have been made in recent years in the eyewear field, particularly with respect to eyewear intended for use in active sports or as fashion sunglasses. These eyewear designs accomplish a variety of functional advantages, such as maximizing interception of peripheral light, reducing optical distortion and increasing the wearer&#39;s comfort level, compared to previous active sport eyewear. 
     Moreover, various other improvements have been made to enhance the durability and strength of eyeglasses. For example, various durable eyeglass designs have been developed that enable eyeglasses to be sturdy even during accidents, impact, stress, and other forms of use or misuse. Further, lenses have also been developed that have enhanced ballistic protection. Thus, an eyeglass can be generally resistant to breaking, bending, or otherwise becoming unusable. 
     SUMMARY 
     A continuing objective in the field of high quality eyewear, particularly that is intended for use in high-speed action sports or military applications, is providing eyewear that exhibits superior ballistic resistance and lens stability. Various improvements have been made that enable a wearer to quickly modify their eyeglass using replaceable components and/or lenses, such by using the systems disclosed in U.S. Pat. Nos. 4,730,915, 5,387,949, and 7,347,545, the entirety of the disclosure of each of which is incorporated herein by reference. Nevertheless, at least one of the embodiments disclosed herein reflects the realization that in order to enhance the ballistic resistance and lens stability of an eyeglass, additional support can be provided to a replaceable or removable lens. 
     Embodiments disclosed herein provide, at least in part, a durable eyeglass design that enables the lens on the eyeglass to be more securely retained by the frame of the eyeglass. The eyeglass can incorporate one or more retention components that may be used in conjunction with traditional lens mounting components, such as those in the systems disclosed in the patent references mentioned above. However, in some embodiments, the retention components can be used independent of traditional lens mounting components. 
     In some embodiments, in response to a ballistic event (such as an impact from a projectile and/or blunt contact with an object), the retention component can advantageously constrain the lens from translational and/or rotational movement in all directions where the lens is engaged and/or supported by the retention component. Such a feature can be contrasted with prior art lens mounting components in that a prior art lens is generally constrained from translational and/or rotational movement in many, but not all directions at a given point along the lens-frame border. Thus, impact from a ballistic event can cause the prior art lens to be dislodged, dislocated, or dismounted from the prior art eyeglass frame. 
     For example, conventional detachable unitary lens systems include an upper frame having a downwardly facing lens groove. The upper edge of a lens is positioned within the lens groove. The lens is retained within the groove by a first interference fit at a first lateral edge of the lens, and a second interference fit at a second lateral edge of the lens. This may provide secure mounting of the lens and good resistance to motion of the lens from side to side relative to the frame during light use of the eyeglass. However, at least the center portion of the lens can be advanced downwardly and out of the lens groove during elastic reconfiguration of the eyeglass following impact. Thus, at least one of the embodiments disclosed herein reflects the realization that prior art eyeglasses fail to provide sufficient ballistic resistance. 
     In contrast, embodiments disclosed herein can securely retain the lens relative to the frame during and after a ballistic impact. For example, the center portion of the lens can be fully seated within the lens groove during and following impact. 
     Such embodiments can be advantageous in that they allow the lens to be securely retained by the frame without undermining or ruining the optical characteristics of the lens. For example, the lens can be secured to and/or supported by the frame in a manner that preserves the as-molded geometry of the lens. 
     Moreover, embodiments disclosed herein can advantageously provide an eyeglass in which the lens can be easily removed and replaced by the wearer while enabling the wearer to mount the lens such that the lens exhibits superior ballistic resistance and the lens stability. 
     For example, in some embodiments disclosed herein, an eyeglass is provided that comprises a frame onto which at least one lens can be mounted. The eyeglass can comprise at least one retention component. The retention component can be mounted onto, carried, or supported by the frame and/or a lens. The retention component can be configured to engage at least a portion of the frame and/or a lens. The retention component can be configured to secure the lens relative to the frame to prevent the lens from separating from the frame in response to a ballistic event. For example, the lens may “separated” from the frame when any portion of the upper edge of the lens is pulled out of the lens groove. 
     The retention component can comprise at least one engagement structure for facilitating engagement with the lens. Further, the retention component can be a system or plurality of components that operate to engage the lens. 
     In some embodiments, the retention component can comprise at least one clip. The clip can be attached along the frame. The clip can be disposed at a central portion and/or lateral portion(s) of the frame, such as centered on the midline of the frame. The clip can be actuated by the wearer in order to secure a central and/or a lateral portion(s) of the lens to the frame. 
     For example, the frame can comprise opposing lateral terminals that interconnect with corresponding projections or detents in the lens in order to mount the lens to the frame in a mounted position while a single clip is used to secure the center portion of the lens to the frame in order to prevent the lens from separating from the frame in response to a ballistic event. Thus, should the eyeglass be subjected to unexpected forces such as would result from being dropped, knocked, or hit by a projectile, the lens will not tend to be separate from the frame. However, multiple clips can also be used to secure the lens relative to the frame along a plurality of portions of points of the lens. 
     In some embodiments, the clip can be rotated relative to and/or about the frame and/or the lens. In some embodiments, the clip can be translated or slid relative to the frame and/or the lens. For example, the retention component can comprise a rotating or translating clip that can be mounted on or supported by the frame of the eyeglass. In some embodiments, the retention component can comprise a rotating or translating clip that can be mounted on, carried, or supported by the lens. The clip can be manually adjusted or actuated by the wearer. The clip can engage directly or indirectly with a portion of the frame and/or the lens. In some embodiments, one or more clips can engage directly or indirectly with a portion of a plurality of lenses, such as a dual lens system. 
     In some embodiments, the clip can comprise an engagement structure such as a tab that is operative to engage and/or interlock with an engagement portion or corresponding surface structure such as a recess or aperture on the frame and/or the lens. 
     For example, the lens can comprise an aperture or slot that can be engaged and/or supported by the tab of the clip. In some embodiments, the clip can have a first rotational/translational position or disengaged position in which the lens can be freely removed downwardly from the frame, enabling disengagement of the lens. The clip can also have a second rotational/translational position or engaged position in which the lens can be secured and/or supported relative to the frame such that the lens does not separate from the frame in response to a ballistic event. 
     The clip can have a hingeless configuration. For example, the clip can be configured as a tubular member that wraps around at least a portion of the frame. The clip can have a hingeless, rotatable configuration in which the clip rotates relative to or about at least a portion of the frame to facilitate engagement of the lens relative to the frame. The clip can also have a hingeless, translatable configuration in which the clip translates along at least a portion of the frame to facilitate engagement of the lens relative to the frame. 
     In some embodiments, the clip can be configured as a split ring having a gap or split. The split ring can encompass or surround a portion of the frame by wrapping around, for example, at least about 50% and/or less than or equal to about 80% of the perimeter or circumference of the portion of the frame, with approximately at least about 20% and/or less than or equal to about 50% of the clip defining the gap or split. In a rotating clip embodiment, the gap or split can be configured such that at least a portion of the lens can be received therein for securing the lens relative to the frame. In such embodiments, the tab can be disposed at one of the free ends forming the gap or split. 
     In some embodiments, a translating clip embodiment can engage a slot in the lens. For example, the lens can be seated against the frame with the clip being positioned adjacent to the slot of the lens in a first translational position or disengaged position. The clip can then be translated within the slot towards a second translation position or engaged position, thus securing the lens relative to the frame. 
     In some embodiments, the clip can be configured to snap-fit onto the frame. The clip can be urged onto the frame with a portion of the frame passing through the gap or split in the clip. In some embodiments, the clip can be fabricated from a resilient material such that the clip deflects to allow enlargement of the gap or split such that the clip can attach to the frame. The clip can therefore be attachable to the frame without requiring pins, latches, or other components. Embodiments disclosed herein can thus allow for superior assembly and maintenance of the eyeglass compared to other designs. Further, the design can be durable and sturdy, providing capable and secure retention despite stresses or other forces that may act on the eyeglass. 
     Further, the clip can rotate with the gap or split being moved from a first rotational position or disengaged position in which a portion of the lens can be received into the gap or split to a second rotation position or engaged position in which the gap or split is rotated such that the clip engages a portion of the lens. Rotation of the gap or split can enable quick and secure engagement with the lens. 
     In some embodiments, the clip can define an outer profile that tapers and blends with the surface of the frame. For example, the clip can define a contour or external shape that blends with a contour or external shape of the frame. In some embodiments, the contour or external shape can blend in only one of the first or second rotational positions. For example, a mismatch in contour can provide a visible and tactile indication that the clip is in a disengaged position while the clip and frame have a generally uniform, smooth contour when the clip is in the engaged position. 
     In some embodiments, the clip can rotate and/or translate about a horizontal axis such that the tab moves in a generally anterior-posterior direction to engage the lens. For example, the tab can be rotated within a generally vertical anterior-posterior plane to align with the lens to engage the lens. Further, the tab can be translated along the frame upon translation of the clip within a generally vertical anterior-posterior plane to align with the lens to engage the lens. 
     In some embodiments, the clip can rotate and/or translate about a vertical axis. In such embodiments, the tab can be rotated within a generally horizontal plane to align with the lens in a generally vertical plane to engage the lens. 
     For example, the engagement structure of the retention component can comprise a tab that is pivotally coupled to the frame such that the tab can rotate about a vertical axis. Optionally, the retention component can comprise a shaft that couples the retention component to the frame. Further, the retention component can optionally comprise an actuating element that is in mechanical communication with the tab such that the actuating element can be used to rotate the tab. 
     In some embodiments, the frame can comprise a recess or aperture configured to receive and/or support the retention component. For example, the recess or aperture of the frame can support the retention component such that a force (exerted in at least one direction) on the retention component is transferred to the frame. The recess or aperture of the frame can optionally be configured to support the retention component such that forces exerted in several directions on the retention component are transferred to the frame. 
     For example, in embodiments wherein the retention component rotates and/or translates about a horizontal axis, the retention component can engage with a horizontal section of the frame. As noted above, the engagement can be a snap-fit engagement. The retention component can fit over the horizontal section and rotate about the horizontal section. Further, the retention component can be weaved into or fit within a horizontally-extending recess or space in the frame. 
     Additionally, in embodiments wherein the retention component rotates and/or translates about a vertical axis, the retention component can engage with a vertical section of the frame. For example, the retention component can fit over the vertical section and rotate about the vertical section. Further, the retention component can be weaved into or fit within a vertically-extending recess or space in the frame. 
     The retention component can also comprise a plurality of clips disposed along the frame of the eyeglass. In such embodiments, the frame of the eyeglass can be configured with or without opposing terminals that are used to engage projections or detents of the lens in order to mount the lens in a mounted position. For example, the plurality of clips can be used as the sole connectors to mount and secure the lens from separating from the frame. 
     Furthermore, the retention component can be formed separately from the frame. For example, the retention component can be coupled to the frame and rotatable or slideable with respect to the frame. In some embodiments, the retention component can be advanced from a first orientation (or a disengaged position) to a second orientation (or an engaged position) in order to engage with the lens. For example, the frame and the retention component can also be configured to permit a predetermined range of rotational or axial movement of the retention component. In one embodiment, the frame can comprise one or more hardstop features that can enter with one or more corresponding detents or recesses in the retention component. The retention component can rotate in a given direction until a hardstop feature of the frame contacts a detents or recess of the retention component to restrict further rotation of the retention component. 
     For example, in embodiments in which the retention component comprises a hingeless clip, the clip can rotate between two or more rotational positions with hardstop features of the clip and the frame restraining motion of the clip at one or more of the positions. For example, the clip can be configured to comprise an interior having one or more protrusions or recesses that engage(s) with one or more protrusions or recesses of the frame. In some embodiments, the hardstop features can be hidden from view when in an assembled state. Further, engagement between the hingeless clip and the frame can also create the desired interaction between the corresponding hardstop features of the clip and the frame. 
     In addition, embodiments are provided in which the lens comprises an engagement portion that can be engaged and/or supported by the retention component. The engagement portion of the lens can comprise at least one of a recess, surface contour, cut-out, projection, slot, aperture, and other such surface structure formed in any variety of shapes and/or sizes. For example, in some embodiments, the engagement portion can be an aperture that extends through the thickness of the lens. The engagement structure can also be a cut-out that extends through the thickness of the lens and extends inwardly from a periphery of the lens. Further, some embodiments can be configured such that the frame comprises an engagement portion that can be engaged by a retention component that is supported by the lens. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The abovementioned and other features of the inventions disclosed herein are described below with reference to the drawings of the preferred embodiments. The illustrated embodiments are intended to illustrate, but not to limit the inventions. The drawings contain the following figures: 
         FIG. 1  is a perspective view of an eyeglass comprising a retention component for securing a lens to a frame of the eyeglass, in accordance with an embodiment of the present inventions. 
         FIG. 2  is a perspective view of a lens comprising a slot that can be engaged by the retention component of the eyeglass shown in  FIG. 1 , according to an embodiment. 
         FIG. 3  is a top perspective view of the frame of the eyeglass shown in  FIG. 1 , according to an embodiment. 
         FIG. 4  is a bottom perspective view of the frame of the eyeglass shown in  FIG. 1 , according to an embodiment. 
         FIG. 5  is an enlarged perspective view of a medial portion of the eyeglass shown in  FIG. 1 , wherein the retention component is in a disengaged position, according to an embodiment. 
         FIG. 6  is a bottom perspective view of a medial portion of the frame, wherein the retention component is in a disengaged position, according to an embodiment. 
         FIG. 7  is an enlarged perspective view of the medial portion of the eyeglass shown in  FIG. 1 , wherein the retention component is in an engaged position, according to an embodiment. 
         FIG. 8  is a bottom perspective view of the medial portion of the frame, where in the retention component is in an engaged position, according to an embodiment. 
         FIG. 9  is a cross-sectional side view of the frame, the retention component, and the lens, wherein the retention component is in the disengaged position and the lens is separated from the frame, according to an embodiment. 
         FIG. 10  is a cross-sectional side view of the frame, the retention component, and the lens, wherein the retention component is in the disengaged position and the lens is seated within a groove of the frame, according to an embodiment. 
         FIG. 11A  is a cross-sectional side view of the frame, the retention component, and the lens, wherein the retention component is in the engaged position with the lens being seated within the groove of the frame such that the retention component engages the lens, according to an embodiment. 
         FIG. 11B  is a cross-sectional side view of the frame, the retention component, and the lens, wherein the retention component is in the engaged position with the lens being seated within the groove of the frame such that the retention component engages the lens, according to another embodiment. 
         FIG. 12  is a perspective view of an eyeglass comprising a retention component for securing a lens to a frame of the eyeglass, in accordance with another embodiment. 
         FIG. 13  is a perspective view of a lens comprising a slot that can be engaged and/or supported by the retention component of the eyeglass shown in  FIG. 12 , according to an embodiment. 
         FIG. 14  is a perspective view of another eyeglass, frame, and retention component according to another embodiment. 
         FIG. 15  is a perspective view of the retention component of the eyeglass of  FIG. 12 , according to an embodiment. 
         FIG. 16  is a cross-sectional front view of the frame of the eyeglass of  FIG. 12 , illustrating a recess configured to support the retention component shown in  FIG. 15 , according to an embodiment. 
         FIG. 17  is a cross-sectional front view of the frame and retention component of the eyeglass of  FIG. 12 , wherein the retention component is in a disengaged position, according to an embodiment. 
         FIG. 18  is a cross-sectional front view of the frame and retention component of the eyeglass of  FIG. 12 , wherein the retention component is in an engaged position, according to an embodiment. 
         FIG. 19  is a cross-sectional front view of the frame and retention component of the eyeglass of  FIG. 12 , wherein the retention component is in the engaged position and engaging the lens, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     While the present description sets forth specific details of various embodiments, it will be appreciated that the description is illustrative only and should not be construed in any way as limiting. Additionally, although particular embodiments of the present inventions may be disclosed or shown in the context of unitary or dual lens eyewear systems, such embodiments can be used in both unitary and dual lens eyewear systems. Further, although embodiments disclosed herein can be used with eyeglasses that have removable and replaceable lenses, embodiments are also contemplated in which the eyeglasses are not intended to provide for removable or replaceable lenses. 
     Further, although particular embodiments may be disclosed or shown in the context of frames having partial orbitals, such embodiments can be used with frames having both full and partial orbitals. Retention components and structures in accordance with embodiments disclosed herein can also be utilized to retain a lens or multi-lens construct within a goggle, such as a ski goggle or motocross goggle. The retention structures may be utilized either as the primary connector or as a secondary connector for cooperation with another lens retention system. Furthermore, various applications of such embodiments and modifications thereto, which may occur to those who are skilled in the art, are also encompassed by the general concepts described herein. 
     For example, some embodiments can provide an eyeglass comprising a frame and at least one retention component or structure. The frame can be configured to support at least one lens in a field of view of a wearer. The frame can comprise a first ear stem and a second ear stem. The frame can be worn on the wearer&#39;s head. The at least one retention component can be supported by the frame and/or by the at least one lens. The at least one retention component can be hingeless. The retention component can be movable relative to the frame and/or to the lens. The retention component can secure the at least one lens relative to the frame. For example, the retention component can engage an engagement portion of the lens for preventing the lens from separating from the frame in response to a ballistic event. Further, some embodiments can be configured such that the frame comprises an engagement portion that can be engaged by a retention component that is supported by the lens. 
     The retention component of the eyeglass can be configured to rotate relative to the frame and/or the lens to engage the respective one of the lens and/or the frame. The retention component can be permanently or detachably mounted on the frame and/or the at least one lens. The retention component can comprise a clip disposed at a central portion of the frame. The clip can be actuated by the wearer to secure a central portion of the lens to the frame. The retention component can be movable from a first orientation in which the lens can be freely moved relative to the frame to a second orientation in which the lens is secured relative to the frame. 
     For example, the retention component can rotate about a generally horizontal axis relative to the frame to engage the frame and/or the lens. Further, the retention component can comprise a rotatable clip mounted on the frame and/or lens. The rotating clip can comprise an engagement structure that is operative to engage the engagement portion of the lens and/or the frame. 
     The rotating clip can also comprise a generally tubular or cylindrical body, and the engagement structure can comprise an engagement tab extending generally circumferentially relative to the cylindrical body. The tubular or cylindrical body can be configured to engage a recess of the frame for mounting the retention component on the frame. The tab can have a first orientation in which the lens is movable relative to the frame and a second orientation in which the tab engages the lens to the secure the lens relative to the frame. For example, the tab of the clip can engage the lens at an angle of at least about 5 degrees and/or less than or equal to about 40 degrees relative to a horizontal plane. In some embodiments, the tab of the clip can engage the lens at an angle of about 19.2 degrees relative to a horizontal plane. 
     Additionally, the retention component can fit over a recess of the frame to be rotatable about a longitudinal axis of the frame. For example, the retention component can fit over the recess in a snap fit. In some embodiments, the engagement portion of the lens can comprise one of a recess and an aperture that can be engaged by the engagement structure of the rotating clip. 
     In other embodiments, the retention component can rotate about a generally vertical axis relative to the frame to engage the frame and/or the lens. For example, the retention component can comprise an actuation handle and at least one tab being rotatable upon rotation of the handle. The tab can extend generally transversely relative to the generally vertical axis. The tab can have a first orientation in which the lens is movable relative to the frame and a second orientation in which the tab engages the lens to the secure the lens relative to the frame. For example, the retention component can rotate in a plane that is generally coplanar with at least a portion of the lens. Additionally, the retention component can comprise an elongate shaft extending between the handle and the tab. Further, the frame can comprise a recess configured to receive at least a portion of the retention component to support the retention component relative to the frame. Furthermore, the handle can be accessible to the wearer for actuating the retention component. 
     In some embodiments, the frame can comprise opposing lateral terminals that interconnect with corresponding projections in the lens to mount the lens to the frame in a mounted position. The frame can comprise a lens groove. The lens groove can extend at least partially along the frame for receiving at least a portion of the lens therein. 
     In some embodiments, the at least one lens of the eyeglass can comprise an engagement portion. Further, the frame of the eyeglass can have a generally horizontal longitudinal axis and a pair of earstems extending posteriorly relative to the frame. The frame can be configured to support the at least one lens in the field of view of a wearer. Further, the eyeglass can be configured such that the at least one retention mechanism is coupled to the frame and rotatable about the longitudinal axis of the frame. The retention mechanism can comprise an engagement structure extending therefrom. The engagement structure can be moveable from a first orientation in which the lens can be freely moved relative to the frame to a second orientation in which the retention structure engages the engagement portion of the lens for securing the lens relative to the frame. 
     The frame can also comprise at least one stop element configured to limit the rotational orientation of the retention mechanism relative to the frame. The retention mechanism can also comprise at least one stop element corresponding to the at least one stop element of the frame. The stop elements can be configured to contact each other to limit the rotational orientation of the retention mechanism relative to the frame. 
     In some embodiments, the retention mechanism can comprise first and second stop elements that interact with the at least one stop element of the frame. The retention mechanism can have a variety of shapes and structural features, such as including a generally cylindrical body with the engagement structure extending generally circumferentially therefrom. For example, the at least one stop element of the retention mechanism can be formed along an interior surface of the retention mechanism. Further, the at least one stop element of the retention mechanism can comprise a recess, and the at least one stop element of the frame can comprise a protrusion. 
     The engagement structure of the retention mechanism can comprise a tab that engages the engagement portion of the lens at an angle of between about at least about 5 degrees and/or less than or equal to about 40 degrees relative to a line that is normal to the lens. Further, in some embodiments, the tab can engage the engagement portion of the lens at an angle of between at least about 10 degrees and/or less than or equal to about 20 degrees relative to a line that is normal to the lens. For example, the tab can engage the engagement portion of the lens at an angle of about 19.2 degrees. 
     With reference to  FIG. 1 , an embodiment of the present inventions is illustrated. In this embodiment, an eyeglass  10  is shown that comprises a pair of ear stems  12 ,  14 , a frame  16 , a retention component  18 , and a lens  20 . The eyeglass  10  illustrated in  FIG. 1  is configured such that the lens  20  can be removed and replaced. However, in other embodiments, the lens may not be removable or replaceable. Nevertheless, such embodiments can provide increased lens stability and ballistic resistance, similar to the embodiment illustrated in  FIG. 1 . 
       FIG. 2  illustrates an embodiment of the lens  20  for use with the eyeglass  10 . The lens  20  can be configured to be supported by the frame  16 . For example, the lens  20  can comprise one or more engagement portions that can be engaged with one or more retention components of the eyeglass for supporting the lens. Further, other structures can be used to support the lens. For example, the frame can comprise one or more opposing terminals and the lens can comprise one or more projections that can be fitted into the terminal(s) of the frame. However, the use of structures such as projections and terminals is optional and can be omitted in some embodiments. For example, structures in addition to the retention component(s) and engagement portion(s) may be unnecessary where two or more retention components and engagement portions are spaced apart along the edge of the lens. 
     As will be appreciated with reference to  FIGS. 1-4 , the lens  20  of the eyeglass  10  can be selectively removed and replaced by the wearer. For example, the wearer can replace the lens  20  with a lens having a different tint or shape. In some embodiments, the wearer can engage interlocking projections or detents of the lens  20  with corresponding opposing terminals of the frame  16  to remove and replace the lens  20 . 
     For example, as shown in  FIGS. 2 and 4 , the lens  20  can comprise a pair of projections  30 ,  32  that can be seated in corresponding terminal recesses  34 ,  36  of the frame  16 . In use, when the projections  30 ,  32  are received within the terminal recesses  34 ,  36  of the frame  16 , the lens  20  can be generally snap fitted into and retained within the lens groove  54  in the frame  16 . Thus, in some embodiments, such an arrangement can provide a further degree of lens retention and stabilization in addition to that provided by the retention component. 
     In accordance with the embodiment shown in  FIGS. 1-4 , the lens  20  can also comprise an engagement portion or structure  50 . The engagement portion  50  can comprise at least one portion of the lens  20  can be one of a recess, surface contour, cut-out, projection, slot, aperture, and other such surface structures and be formed in a variety of shapes and/or sizes. For example, in the illustrated embodiment, the engagement portion  50  is shown as an aperture that extends through the thickness of the lens  20 . The engagement portion  50  is shown as a single aperture, but can be formed as a plurality of apertures. The engagement portion  50  can extend generally parallel relative to a line that is normal to the lens  20  (as shown for example, in  FIG. 11A ). Further, the engagement portion  50  can extend generally transversely relative to a line that is normal to the lens  20  (as shown for example, in  FIG. 11B ). 
     The engagement portion  50  can be disposed at any point along the lens  20 , and preferably, at any point along the lens-frame boundary  52  of the lens  20 . The lens-frame boundary can be defined as the portion or portions of the lens along which the lens and the frame border, overlap, or interconnect with each other. For example, referring to  FIGS. 1-2 , the lens-frame boundary  52  is generally the upper section of the lens  20 , adjacent to the upper edge of the lens  20  that is seated within a groove  54  of the frame  16  (shown in  FIG. 4 ). Thus, although a single engagement portion  50  is used in the embodiment of the lens  20  shown in  FIG. 2 , other embodiments of the lens  20  can be constructed that comprise two or three or four or more engagement portions  50  disposed along the lens-frame boundary  52 . 
     Additionally, as mentioned above, although the engagement portion  50  is shown as an aperture, the engagement portion  50  can also comprise a protrusion, a detent, and/or other shapes and sizes of engagement portions that allow the lens  20  to be interconnected with the retention component  18 . Furthermore, as noted above, the lens  20  can comprise a unitary or dual lens system. For example, one or more engagement portions can be used in each lens of a dual lens system, as desired. Moreover, the lens  20  can be mounted within an orbital-type frame. The lens-frame boundary  52  can extend around a perimeter of the lens  20  (or the perimeters of both lenses in a dual lens system). In such embodiments, one or more engagement portions can be selectively disposed along lower portions, lateral portions, or medial portions (such as adjacent to the nosepiece opening of the lens), and the frame can also comprise corresponding retention components configured to engage the respective engagement portion(s) of the lens(es). 
     With reference to  FIGS. 5-8 , the function and operation of an embodiment of the retention component  18  will now be described. In  FIGS. 5-6 , the retention component  18  is disposed in a disengaged position  70 . Additionally, in  FIGS. 7-8 , the retention component  18  is disposed in an engaged position  72 . As will be appreciated by one skill in the art, when the retention component  18  is disposed in the disengaged position  70 , the retention component  18  is not engaged with the corresponding engagement portion  50  of the lens  20 . However, when the retention component is disposed in the engaged position  72 , the retention component  18  can engage the engagement portion  50  of the lens  20 , as shown in  FIG. 7 . 
     In order to facilitate engagement with the engagement portion  50  of the lens  20 , the retention component  18  can comprise a projection or recess that engages with the corresponding engagement portion  50 . As shown in  FIGS. 5-8 , the retention component  18  can comprise a tab  80  that extends from a body  82  of the retention component  18 . In the illustrated embodiment, the tab  80  can be configured to fit within or be seated within the aperture of the engagement portion  50 . The tab  80  of the retention component  18  provides an interference engagement to prevent the lens  20  from detaching from the frame  16  or exiting the lens groove  54  of the frame  16 . 
     As also shown in  FIGS. 5-8 , in some embodiments, the retention component  18  can be a hingeless clip that defines an outer profile that tapers and blends with the surface of the frame  16 . For example, the clip  18  can define a contour or external shape that blends with a contour or external shape of the frame  16 . In some embodiments, the contour or external shape can blend in only one of the first or second rotational positions. For example, (as shown in  FIGS. 5-6 ) a mismatch in contour can provide a visible and tactile indication that the clip  18  is in a disengaged position while the clip  18  and frame  16  have a generally uniform, smooth contour when the clip is in the engaged position (as shown in  FIGS. 7-8 ). 
     Referring to  FIGS. 9-11B , embodiments of the retention component  18  are shown as a rotatable component that is coupled to the frame  16 . The body  82  of the retention component  18  can be configured as a generally annular or tubular shape that wraps around at least a portion of the frame  16 . For example, the body  82  can be configured as a split ring (as visible in the side views of  FIGS. 9-11 ) that encompasses or surrounds a portion of the frame  16 . The retention component  18  can wrap around, for example, at least about 50% and/or less than or equal to about 80% of the perimeter or circumference of a portion of the frame  16 , with at least about 20% and/or less than or equal to about 50% of the retention component  18  defining a gap or split  90 . 
     Further, the gap or split  90  can be configured such that at least a portion of the lens can be received therein for securing the lens relative to the frame  16 . Thus, when rotated to the disengaged position  70 , the gap or split  90  can align with a portion of the frame  16 , such as the groove  54 . As a result, the retention component  18  can allow passage of at least a portion of the lens  22  into the groove  54  of the frame  16 . Furthermore, in the embodiments shown in  FIGS. 5-11B , the tab  80  can be disposed at one of the free ends forming the gap or split  90 . The retention component  18  can be rotated from the first rotational position or disengaged position to the second rotation position or engaged position in which the tab  80  and gap or split  90  is rotated such that the tab  80  of the retention component  18  engages a portion of the lens. Rotation of the gap or split can enable quick and secure engagement with the lens. 
     In some embodiments, the retention component  18  can be configured to snap-fit onto the frame  16 . In embodiments wherein the retention component is a clip  18 , the clip can be urged onto the frame  16  with a portion of the frame  16  passing through the gap or split  90  in the clip. In some embodiments, the clip can be fabricated from a resilient material such that the clip deflects to allow enlargement of the gap or split  90  such that the clip can attach to the frame  16 . The clip can therefore be attachable to the frame  16  without requiring pins, latches, or other components. Embodiments disclosed herein can thus allow for superior assembly and maintenance of the eyeglass compared to other designs. Further, the design can be durable and sturdy, providing capable and secure retention despite stresses or other forces that may act on the eyeglass. 
     In some embodiments, the retention component  18  can be configured to be mounted to the lens  22  such that the retention component  18  engages a corresponding retention structure in the frame  16  when the lens  22  is mounted onto the frame  16 . For example, the retention component  18  can be mounted such that the retention component  18  is movable relative to the lens  22 . However, the retention component  18  can be fixed relative to the lens  22 . The retention component  18  can be permanently mounted to the lens  22 . The retention component  18  can be detachably mounted to the lens  22 . Accordingly, in some embodiments, it is not necessary for the clip or retention component  18  to be part of or carried or supported by the frame  16 . The various embodiments and features discussed herein with respect to the retention component  18  in embodiments wherein the retention component  18  is carried or supported by the frame  16  can be incorporated into embodiments wherein the retention component  18  is mounted onto the lens  22 . 
     As shown in  FIG. 10 , the lens  20  can be seated within the groove  54  of the frame  16  when the retention component  18  is positioned in the disengaged position  70 . Next, when the retention component  18  is rotated to the engaged position  72 , as shown in  FIG. 11 , the tab  80  of the retention component  18  is advanced to a position within the aperture of the engagement portion  50  of the lens  20 . As a result, the lens  20  can be generally constrained from movement in all directions at the point of engagement with the frame  16  in the retention component  18 . 
     For example, the eyeglass  10  can tend to provide superior ballistic resistance and lens stability during use. Further, embodiments of the eyeglass can be provided in which one or more retention components are utilized to attach the lens to the frame. In such embodiments, the lens can be coupled to the frame in a matter that does not distort the lens or undermine its optical qualities. As a result, embodiments of the eyeglass disclosed herein can not only provide superior ballistic resistance and lens stability, but can also provide superior optical quality. 
     Additionally, as shown in the embodiments of  FIGS. 9-11B , the eyeglass can comprise a motion constrain mechanism. For example, the retention component  18  can comprise one or more stop elements that are configured to interact with one or more stop elements of the frame  16 . For example, the retention component  18  can comprise posterior stop elements  92  and upper and lower anterior stop elements  93 ,  94  that are configured to interact with respective ones of a posterior stop element  96  and an anterior stop element  98  of the frame  16 . As illustrated in  FIGS. 9-11 , the stop elements  92 ,  93 ,  94 ,  96 ,  98  can restraint rotational movement of the retention component  18  relative to the frame  16 . For example, the use of stop elements  92 ,  93 ,  94 ,  96 ,  98  can facilitate accurate movement from the disengaged position  70  the engaged position  72  and vice versa. Further, in some embodiments, the stop elements  92 ,  93 ,  94 ,  96 ,  98  can also be used to lock the retention component  18  relative to the frame  16  such that relative rotational movement is prevented. Such a feature can be advantageous once the retention component  18  is moved to the engaged position  72  where it can be snapped into place or otherwise retained to prevent inadvertent disengagement. 
     In the illustrated embodiment, the frame  18  comprises a pair of stop elements  96 ,  98  formed as protrusions extending from an outer surface of the bridge portion of the frame  16 . Although two stop elements  96 ,  98  are shown, a single stop element can also be used. Further, in embodiments where two stop elements are used, the stop elements can provide different functions for the retention component  18 . 
     For example, the posterior stop element  96  can be relatively larger than the anterior stop element  98  and primarily provide a restraint against rotation in a given direction. The anterior stop element  98  can provide an engagement function that tends to constrain or substantially fix the rotation position of the retention component  18 . The posterior stop element  96  can tend to constrain the rotational position of the retention component  18 . 
     In use, with some initial effort to overcome the engagement between the lower, anterior stop element  98  and the lower, anterior stop element  94  of the retention component  18 , the retention component  18  can move from the first rotational position or disengaged position  70 . The retention component  18  can continue to rotate until being rotationally constrained or stopped by the posterior stop element  96  and the anterior stop element  92 . Further, the retention component  18  can be substantially constrained at the second rotational position or engaged position  72  due to engagement between the anterior stop element  98  and the upper, anterior stop element  93 . Although the illustrated embodiment shows at least two stop elements of the retention component  18  interacting with at least two stop elements of the frame  16 , the motion constraint mechanism can comprise a single stop on the frame and a single stop on the retention component; the stops can interact to provide rotational restraint and substantial fixation of the rotational position. 
     Therefore, in such embodiments in which the retention component  18  comprises a hingeless clip, the clip can rotate between two or more rotational positions with hardstop features or stop elements  92 ,  93 ,  94 ,  96 ,  98  of the clip and the frame  16  restraining motion of the clip at one or more of the positions. As shown, the retention component  18  can comprise an interior surface having one or more recesses  92  that engage with one or more protrusions  94  of the frame  16 . Further, the retention component  18  can comprise an interior surface having one or more protrusions that engage with one or more recesses of the frame  16 . In some embodiments, the hardstop features can be hidden from view when in an assembled state. Further, engagement between the hingeless clip and the frame can also create the desired interaction between the corresponding hardstop features of the clip and the frame. 
     Although  FIGS. 9-11B  illustrate embodiments of the retention component  18  as being rotatable relative to the frame  16 , the retention component  18  can be configured to pivot or slide relative to the frame  16 . In some embodiments, the retention component  18  could be pivotally coupled to a portion of the frame  16 . However, in the illustrated embodiment, the retention component  18  is configured to rotate around the frame  16  in order to allow the tab  80  to engage the engagement portion  50  of the lens  20 . 
     Further, the retention component  18  can comprise a resilient material, such as a compressible or flexible material disposed at least along the tab  80  of the retention component  18 . As a result, a ballistic event will not tend to result in damage at the interconnection between the retention component  18  and the engagement portion  50 . In such embodiments, the tab  80  can be formed from such a resilient or flexible material or comprise a coating, layer, or one or more surface features formed from the resilient or flexible material. The retention component  18 , such as the tab  80  and/or the resilient or flexible material, can have a modulus of elasticity that is less than that of the lens. Further, retention component  18 , such as the tab  80  and/or the resilient or flexible material, can have a modulus of elasticity that is less than that of the frame. Accordingly, at least a portion of the retention component  18  can dampen or absorb force or vibration from a ballistic event. 
     Further, the retention component  18  can be configured such that during rotation of the retention component  18  and engagement with the engagement portion  50  of the lens  20 , the lens  20  can be brought into the groove  54  to secure the lens  20  within the groove  54 . Such a feature can be facilitated using a cam-like motion of the retention component  18  or a cam-like interaction between the tab  80  and the engagement portion  50 . 
     In some embodiments, the tab  80  of the retention component  18  can engage the engagement portion  50  of the lens  20  in the engaged position (as shown in  FIGS. 11A-11B ) at a desired engagement angle  100  configured to maximize stability, retention, and resilience of the eyeglass in response to a ballistic event. 
     The engagement angle  100  can be defined as the angle measured between the tab  80 , such as a longitudinal or circumferential centerline or tab axis  102 , and a line  104  that is normal to the lens  20 . The normal line  104  can be the line that is normal to the lens  20  at approximately the engagement portion  50  of the lens  20 . 
     In some embodiments, the line  104  can be generally parallel with the axis  106  of the engagement portion  50 , as shown in the embodiment of  FIG. 11A . Further, in some embodiments, the tab axis  102  can be generally parallel with a longitudinal centerline or axis  106  of the engagement portion  50  of the lens  20 . For example, as shown in the embodiment of  FIG. 11B , the tab axis  102  can be generally parallel with the axis  106  of the engagement portion  50  and oriented transversely relative to the normal line  104  of the lens  20 . 
     The engagement angle  100  can be oriented to ensure optimal retention of the lens  20  relative to the frame  16 . For example, in either of the embodiments shown in  FIGS. 11A-11B  and other embodiments, the engagement angle  100  can be at least about 5 degrees and/or less than or equal to about 40 degrees relative to a horizontal plane. Further, in some embodiments, the tab  80  can engage the engagement portion of the lens at an engagement angle  100  of at least about 10 degrees and/or less than or equal to about 30 degrees relative to a horizontal plane. In some embodiments, the engagement angle  100  can be approximately 12 degrees. In other embodiments, such as the embodiment of  FIG. 11B , the engagement angle  100  of approximately 19.2 degrees has been found to provide excellent results in ballistic testing. 
     Furthermore, the rotational range of the retention component  18  between the engaged and disengaged positions can be at least about 10 degrees and/or less than or equal to about 180 degrees. For example, as shown in  FIGS. 10-11B , the retention component  18  can rotate about 45 degrees from the engaged position to the disengaged position. 
     In some embodiments, the tab  80  retention component  18  can engage the engagement portion  50  of the lens  20  with a leading end  110  of the tab  80  extending through the engagement portion  50 . For example,  FIGS. 11A-B  illustrates that the leading end  110  extends to the other face or through the width of the lens  20 . However, the leading end  110  can extend only partially into the engagement portion  50  or beyond the engagement portion  50 . For example, the leading end  110  can extend through the engagement portion  50  at least about 5 degrees and/or less than or equal to about 90 degrees. Thus, the leading end  110  can be rotated down from the frame  16 , through the lens  20 , and back toward the frame  16 . In some embodiments, the leading end  110  can snap fit or engage the frame  16  to reach a locked fit in the engaged position. 
     Referring now to  FIGS. 12-19 , another embodiment of an eyeglass having a retention mechanism is shown.  FIG. 12  is a perspective view of an eyeglass  300  that comprises a frame  302 , a pair of ear stems  304 ,  306  extending rearwardly from the frame  302 , a lens  308 , and a retention mechanism  310 . In this embodiment, the retention mechanism  310  can be concealed within the frame  302  such that the eyeglass  300  maintains the appearance of a conventional eyeglass while exhibiting excellent ballistic properties. 
       FIG. 13  illustrates an embodiment of a lens  308  for use with an eyeglass. The lens  308  can be configured to be supported by the frame  302 . For example, the lens  308  can comprise one or more engagement portions that can be engaged with one or more retention components of the eyeglass for supporting the lens. Further, other structures can be used to support the lens. For example, the frame can comprise one or more opposing terminals and the lens can comprise one or more projections that can be fitted into the terminal(s) of the frame. However, the use of structures such as projections and terminals is optional and can be omitted in some embodiments. For example, structures in addition to the retention component(s) and engagement portion(s) may be unnecessary where two or more retention components and engagement portions are spaced apart along the edge of the lens. 
     In some embodiments, the lens  308  can comprise a pair of projections  320 ,  322  that can be seated in corresponding terminal recesses  324 ,  326  of the frame  302 . Further, the lens  308  can comprise an upper edge or boundary  330 . In use, when the projections  320 ,  322  are fitted into the recesses  324 ,  326  of the frame  302 , the upper edge or boundary  330  of the lens  308  can be generally snap-fitted into and retained within a lens groove  332  of the frame  302 . Thus, in some embodiments, such an arrangement can provide a further degree of lens retention and stabilization in addition to that provided by the retention component. 
     In accordance with the embodiment shown in  FIGS. 12-19 , the lens  308  can also comprise an engagement portion  350 . The engagement portion  350  can comprise at least one portion of the lens  308  can be one of a recess, surface contour, cut-out, projection, slot, aperture, and other such surface structures and be formed in a variety of shapes and/or sizes. For example, in the illustrated embodiment, the engagement portion  350  is shown as a cut-out that extends through the thickness of the lens  308 . Further, the engagement portion  350  is shown as a single cut-out, but can be formed as a plurality of cut-outs. Additionally, the engagement portion  350  can be formed to comprise a narrowed section  352  and a wide section  354 . 
     Referring now to  FIG. 15 , an embodiment of a retention component  360  is shown. The retention component  360  can be configured to engage and secure the lens  308  relative to the frame  302 . For example, the retention component  360  can be positioned in one of an engaged position and a disengaged position. In the engaged position, the retention component  360  can interlock, engage, and/or otherwise secure at least a portion of the lens  308  relative to the frame  302 . In the disengaged position, the retention component  360  can allow the lens  308  to move freely relative to the frame  302 . Further, the retention component  360  can be manually actuated by the wearer in order to allow the wearer to interchange lenses. 
     In the illustrated embodiment, the retention component  360  can comprise a switch or handle  362  and at least one tab  364 . The retention component  360  can be configured to rotate about a generally vertical axis relative to the eyeglass  300 . The handle  362  can be actuated by the wearer. In some embodiments, the retention component  360  can comprise an elongate shaft  366  extending between the handle  362  and the tab  364 . Further, some of us can be configured such that the retention component  360  comprises a pair of tabs  364 . As shown, the tab(s)  364  can extend in generally opposite horizontal directions and be attached to a lower or bottom end of the retention component  360 . 
     The tab  364  can be disposed adjacent to the lens  308  for engaging the lens  308  such that the tab  364  can be positioned in an engaged position or a disengaged position relative to the lens  308  for engaging lens  308 . The engaged and disengaged positions of the retention component  360  relative to the frame  302  are shown in  FIGS. 17 and 18 . Further,  FIG. 19  illustrates the retention component  360  engaging the lens  308  in the engaged position. 
       FIG. 14  is an enlarged perspective view of the eyeglass  300  and the retention mechanism  310 .  FIG. 16  is a cross-sectional front view of the frame  302  of the eyeglass  300  taken along lines of  FIG. 12 . As illustrated, the frame  302  can comprise a recess  370  configured to support the retention component  360  shown in  FIG. 15 , according to an embodiment.  FIG. 16  also illustrates the lens groove  332  extending along the frame  302 . The recess  370  can be configured to allow the tab  364  of the retention component  360  to be passed downwardly toward the lens groove  332 . Further, the recess  370  can comprise a handle-receiving section  372  at an upper end thereof for accommodating at least a portion of the handle  362  of the retention component  360 . As shown in  FIG. 14 , the recess  370  can comprise a rotational step-wise distribution of gaps. The gaps can be configured to allow the tab(s)  364  of the retention component  360  to be rotated as it is advanced into the recess  370 , which rotation can limit axial or vertical movement of the retention component  360  (and unintentional removal of the retention component  360  from the recess  370 ). In this manner, the retention component  360  can be securely seated into and retained by the recess  370 . In use, the recess  370  can allow the retention component  360  to rotate therein with the handle  362  being pivotable within the section  372  of the recess  370 . Further, the frame  302  can comprise a bump  374  that provides interference and/or frictional resistance to movement of the handle  362  thereover. Thus, unintentional rotation and disengagement of the retention component  360  can be generally prevented. 
     Additionally, as shown in  FIGS. 17 and 18 , when the retention component  360  is disposed in the recess  370 , the tab  364  can be positioned within or extend within the lens groove  332 . Accordingly, the tab  364  can be rotated such that the retention component  360  is in the disengaged position, as shown in  FIG. 17 . When the retention component  360  is in the disengaged position, the lens  308  can be positioned within the lens groove  332  with the tab  364  fitting into the narrowed section  352  of the engagement portion  350  of the lens  308 . Further, as shown in  FIG. 19 , the retention component  360  can be rotated to the engaged position such that the at least one tab  364  rotates to fit within the widened section  354  of the engagement portion  350  of the lens  308 . The retention component  360  can thus be rotated in a plane that is generally coplanar with the engagement portion  350  of the lens. Thus, the retention component  360  can rotate within the engagement portion  350  of the lens  308  in order to selectively engage or disengage with the lens. 
     The embodiment shown in  FIGS. 12-19  enables the retention component  360  to interlock or couple the lens  308  relative to the frame  302 . Notably, with the upper edge or boundary  330  of the lens  308  being fitted into the lens groove  332  and with the tab  364  engaging the engagement portion  350  of the lens  308 , the lens  308  can be generally constrained against translational and rotational movement with respect to the frame  302 . The ballistic strength of the eyeglass can be substantially increased with such a design. 
     The retention component taught herein can provide excellent ballistic resistance for the lens and the frame of the eyeglass. The retention component can be integrated into, carried, or supported by the frame of the eyeglass. The retention component can also be integrated into, carried, or supported by the lens or lenses supported by the frame. The retention component can also be formed as a separate part that can be retrofitted onto existing eyewear. In some embodiments, the retention component can restrict rotational and/or translational movement of the lens relative to the frame at one or more points of the engagement between the lens and the frame. Further, the retention component can comprise a portion of the frame and/or a portion formed separately from the frame that engages with a portion of the lens. 
     Some of the embodiments discussed herein provide for a retention component that performs the function of engaging the frame separately from the function of engaging the lens. However, the retention component can engage both the frame and the lens together. For example, the retention component can engage a protrusion of the frame onto which the lens is mounted, thus engaging the frame and engaging and restricting movement of the lens. 
     Embodiments of the eyeglass disclosed herein can tend to ensure that the lens does not become substantially separated from the frame in response to a ballistic event. Further, embodiments of the eyeglass can be configured such that any force transmitted to the lens is also transmitted to the frame of the eyeglass while substantially maintaining engagement between the lens and the frame. For example, although the lens of such an eyeglass may be damaged (cracked or chipped), the lens may not be shattered or displaced relative to the frame. This ballistic resistance can provide excellent protection to the wearer. 
     Additionally, the retention component can comprise a resilient material, such as a compressible or flexible material disposed at least along a portion of the retention component. For example, a tab, connector, body, or other structure or component of the retention component can be formed from and/or include one or more resilient materials. As a result, a ballistic event will not tend to result in damage at the interconnection between the retention component and the engagement portion. In some embodiments, a tab of the retention component can be formed from a resilient or flexible material or comprise a coating, layer, or one or more surface features formed from the resilient or flexible material. The retention component, such as the tab and/or the resilient or flexible material, can have a modulus of elasticity that is less than that of the lens. Further, retention component, such as the tab and/or the resilient or flexible material, can have a modulus of elasticity that is less than that of the frame. Accordingly, at least a portion of the retention component can dampen or absorb force or vibration from a ballistic event. 
     The eyeglass can comprise a plurality of retention components that engage the lens and/or the frame to secure the lens relative to the frame. For example, a lens of the eyeglass can be engaged and/or supported at two or more points along the upper edge or boundary thereof. 
     In an embodiment that comprises a unitary lens, the lens can be engaged and/or supported at least at both lateral sides and a central portion thereof. For example, a unitary lens may be secured to and/or supported by a frame using a first retention structure on the left side of midline and a second retention structure on the right side of midline. The retention structures can include any of the clips or other mechanisms disclosed herein. The first retention structure may be centered on a point that is within the left lateral one third of the length of the frame, measured hinge to hinge. The second retention structure may be centered on a point that is within the right lateral one third of the frame. A third retention structure may also be used, located within the central one third of the frame, preferably on the midline. Four or five or more retention structures may also be used, depending upon the desired performance. Typically, the retention structures can be symmetrically spaced apart along the length of the frame, or as a mirror image across the plane of symmetry (anatomical midline). 
     In an embodiment that comprises dual lenses, each lens can be engaged and/or supported by at least one retention component. For example, a dual lens may be secured to and/or supported by the frame using a first retention structure on the left side of a midline and a second retention structure on the right side of the midline. In some embodiments, a dual lens can be secured by three or more retention components, for example, at both lateral sides and a central portion thereof. Alternatively, a dual lens may be secured by a single retention component and by engagement between the dual lens and the frame, such as with a protrusion, catch, or tab that engages a recess of the frame. As with the unitary lens embodiments discussed above, typically, the retention structures can be symmetrically spaced apart along the length of the frame, or as a mirror image across the plane of symmetry (anatomical midline). 
     Although embodiments of these inventions have been disclosed in the context of certain examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. In addition, while several variations of the inventions have been shown and described in detail, other modifications, which are within the scope of these inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the inventions. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions.