Patent Publication Number: US-11378819-B2

Title: Multi-component contact lens having posterior and anterior features

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 16/544,404 filed Aug. 19, 2019, which is a continuation of U.S. application Ser. No. 15/274,255, filed on Sep. 23, 2016, the contents both of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to an ophthalmic device, and in particular, relates to a wearable contact lens. 
     BACKGROUND INFORMATION 
     On-eye wearable ophthalmic devices, such as contact lenses, may be formed in a variety of structures, such as soft contact lenses, hard contact lenses, and hybrid contact lenses, to name a few. A hybrid contact lens is a combination of soft and hard contact lens technologies. The various structures have their own advantages and disadvantages. For example, soft lenses may be easier to fit and be more comfortable to wear than hard lenses, but they may not provide quality optics as do the hard lenses. Conversely, hard lenses may be difficult to fit, which typically require iterative fittings with different curvatures to settle on a comfortable fit. While hybrid lenses may provide some combination of the benefits of each, they may typically still require multiple fittings to obtain the desired comfortable fit. 
     While various designs have been tried, the disadvantages of the various designs persist. These disadvantages, if not addressed, may increase the complexity of design, manufacturing and stock maintenance of future lenses. As such, it may be desirable to reduce or eliminate such disadvantages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Not all instances of an element are necessarily labeled so as not to clutter the drawings where appropriate. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described. 
         FIG. 1  is an illustrative plan view of an ophthalmic system including posterior and anterior features in accordance with an embodiment of the disclosure. 
         FIG. 2  is an illustrative perspective view of an ophthalmic device including posterior and anterior features in accordance with an embodiment of the disclosure. 
         FIG. 3  is an illustrative cross-sectional view of a central area of an ophthalmic device including posterior and anterior features in accordance with an embodiment of the disclosure. 
         FIG. 4  is an illustrative plan view of an ophthalmic device including posterior and anterior features in accordance with an embodiment of the disclosure. 
         FIG. 5  is a functional block diagram of an ophthalmic device including posterior and anterior features in accordance with an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of an ophthalmic device having tear fluid exchange features, and alignment features are described herein. For example, channels formed on a posterior side of the ophthalmic device may provide for tear fluid exchange between the cornea under the ophthalmic device and the eye external to the ophthalmic device. Additionally, features formed on an anterior side of the ophthalmic device may provide for alignment of an insert of the ophthalmic device with an enclosure of the ophthalmic device. In the following description numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     As discussed above, the various conventional contact lens structures all have their own advantages and disadvantages. These advantages and disadvantages may also affect smart contact lenses. The advent of electronic lenses, e.g., smart contact lenses, may include electronics and sensors that provide various functionality. Such electronic lenses, however, may be similar in structure to hybrid lenses due to the electronics and sensors being desirably enclosed in a biocompatible material. Smart contact lenses may include dynamic optics and associated control electronics, which may provide accommodation through the control of the dynamic optic. Smart contact lenses may be similar in structure to hybrid lenses in that they include an insert disposed within an enclosure, where the insert may house the dynamic optics and associated control. Hybrid lens-type structures, however, may include various problems that may affect their wearability and fitting. These features may pose difficulties in fabrication and adoption of smart contact lenses by the lens-wearing public. 
     For example, hybrid lenses may require iterative fittings to ensure proper fit on a user&#39;s eye. The difficulty in fitting may be due to the insert, which may be rigid, and how the insert affects the comfort of the lens. Additionally, suction of the hybrid lens to the user&#39;s eye may cause difficultly in removal by the user, which may cause incidents of requiring their removal by an eye care provider. Exchange of tear fluid from on and around the central cornea with fresh tear fluid may also be difficult if the hybrid lens does not include passageways for such exchange. In some instances, lack of fresh tear fluid and oxygen may lead to damage of the cornea. The problem with suction and the lack of tear fluid exchange may be due to the same hybrid lens features, and may both be present. 
     Moreover, due to the iterative fitting process, each pair of hybrid lenses are essentially personalized, which requires fabrication of numerous hybrid lenses. The number of hybrid lenses, which may equal the number of wearers, may complicate manufacturing, assembly, and inventory management. 
     As such, it may be desirable to have a small number of hybrid lens designs per optical prescription. Such hybrid lenses may ease manufacturing allowing for high volume processing instead of individualized fabrication. Additionally, the one or two hybrid lenses may include features that allow for the exchange of tear fluid and ease of lens removal, e.g., that also reduce or eliminate the incident of suction. Further, the hybrid lens may include alignment features that may simplify assembly and that provide alignment fiducials for obtaining centricity between an insert and an enclosure. 
     For example, the present disclosure may provide for an enclosure that may encapsulate a pre-formed semi-rigid to rigid insert such as a rigid gas permeable contact lens or an electronic insert, rigid or soft. The enclosure may include geometries and/or features that may provide a variety of benefits. For example, the enclosure&#39;s features may provide a means for aiding fabrication during over molding of contact lens enclosure material by incorporating internal standoff features. Additionally, enclosure features may provide anterior channel/vent contours that may prevent or reduce the incidence of mechanical suction of the lens to the eye during wear, thereby facilitating lens removal. The enclosure may include posterior contours that allow the contact lens to fit onto a wide population of contact lens wearers. The enclosure features may further provide fiducials useful as assembly aids and/or post-fabrication inspection. Lastly, the enclosure may include geometries and features that may provide enhanced tear fluid exchange in and around the central cornea region. 
       FIG. 1  is an illustrative plan view of an ophthalmic device  100  including posterior and anterior features in accordance with an embodiment of the present disclosure. The ophthalmic device  100  may be an on-eye wearable device or an implantable device. The ophthalmic device  100 , for example, may be placed over a user&#39;s cornea to provide various optical and/or benefits, such as vision correction, accommodation, medical monitoring, and the like. Alternatively, the ophthalmic device  100  may be an intraocular device amenable to implantation into a user&#39;s eye. The ophthalmic device  100  may include an insert  102  disposed in an enclosure  104 . The enclosure  104  may have various features formed on a posterior and/or an anterior side to enhance wearability and/or assembly. In some embodiments, the posterior side and/or anterior side features may have discrete rotational symmetry of the nth order, where n may be an odd number greater than or equal to three. 
     The insert  102  may provide optical properties to the ophthalmic device  100 , such as static and/or dynamic optical power, and may be positioned over a central area of a user&#39;s cornea when the ophthalmic device is worn on the eye. The insert  100  may have the form of a semi-spherical shell having a diameter, a radius of curvature of a posterior side and a radius of curvature of an anterior side. The posterior side may be an eye-facing side, whereas the anterior side may be an external facing side. Stated another way, the posterior side may be concave and the anterior side may be convex. In some embodiments, the insert  102  may be around 10 mm in diameter, and have a radius of curvature on the posterior side of around 8 mm. The insert  102  may have various thicknesses, and in some embodiments may change in thickness in a radial direction from a central axis to a perimeter. The thickness of the insert, however, may be a non-limiting aspect of the present disclosure. 
     The insert  102  may be rigid or soft. In some embodiments, the insert  102  may be a pre-formed rigid insert that is formed from a rigid, gas permeable polymer. In some embodiments, the insert  102  may be soft, and formed from a biocompatible elastomer, such as a silicone elastomer, for example. In some embodiments, the insert  102  may include control logic and a dynamic optic controlled by the control logic. Additionally, in some embodiments, the insert  102  may be formed from multiple components. In general, the insert  102  may be enclosed in the enclosure  104  and, when worn by a user, be centrally located over the user&#39;s cornea to provide one or more optical properties to the user. 
     The enclosure  104  may envelope the insert  102  and may include various features, such as contours, ridges, fenestrations, bumps, etc., that provide various assembly and wearability aspects to the ophthalmic device  100 . The enclosure  104  may be formed from a flexible, biocompatible polymer. For example, the enclosure  104  may be formed from a hydrogel, silicone hydrogel, or silicone elastomer. The enclosure  104  may also be referred to as an over mold or an encasement. Similar to the insert  102 , the enclosure  104  may have the form of a semi-spherical shell having a diameter, a posterior side, e.g., eye-ward facing side, and an anterior side, e.g., external facing side. The posterior side may be concave and correspond to the posterior side of the insert  102 , while the anterior side may be convex and correspond to the anterior side of the insert  102 . The posterior side may be characterized by having multiple radii of curvatures, which may be different in different areas of the ophthalmic device  100 . For example, a radius of curvature of the enclosure  104  in a center area  106 , which may include the diameter of the insert  102 , may be different than a radius of curvature of the enclosure  104  in a skirt area  108 , which may be radially outside of the insert  102 . The center area  106  may also be referred to herein as the optical area  106 . Desired radii of curvature for the center area  106  and the skirt  108  may allow the ophthalmic device  100  to fit a majority of the eye population. The anterior side may have different radii of curvature, or it may have a single radii of curvature. The radii of curvature of the anterior side may be such as to correct for one or more of myopia, hyperopia, presbyopia, and/or astigmatism of the wearer, for example. Further, the diameter of the enclosure  104  may be greater than the diameter of the insert  102 . For example, the diameter of the enclosure  104  may range from 13 to 16 mm. 
     The enclosure  104  may include a cornea contact  110  formed therein and disposed at least under a portion of the perimeter of the insert  102  on the posterior side of the enclosure  104 . The cornea contact  110  may be a discontinuous toroidal-shaped ring that provides a cornea contact area to the ophthalmic device  100 . The cornea contact  110  may contact the user&#39;s eye outside of the central cornea to position the ophthalmic device  100  over an optic area of the eye. An amount of area of the cornea contact  110  may affect the wearability, e.g., comfort, of the ophthalmic device  100 , with more area improving comfort. While increasing the area of the cornea contact  110  may improve wearability, the amount of area available may be limited, at least in part, by the center area  106 . 
     The cornea contact  110  may be formed from a raised area on the posterior side of the ophthalmic device  100 . For example, the cornea contact  100  may be formed in or on a posterior side of the enclosure  104 . Depending on the height of the cornea contract  110 , an amount of clearance between a posterior side of the enclosure  104  and the central cornea of the user&#39;s eye may be obtained. The clearance may form a chamber between the central cornea and the posterior side of the ophthalmic device  100  which may be, at least partially, encircled by, e.g., enclosed by or at least partially enclosed by, the cornea contact  110 . The chamber, which may also be referred to herein as a tear fluid chamber, may provide a volume for tear fluid to accumulate over the central cornea. 
     The enclosure  104  may further include one or more channels  112 . The channels  112  may be formed in or on the posterior side of the enclosure  104  and may extend through the cornea contact  110  in one or more areas. In some embodiments, the channels  112  may form the discontinuous portions of the cornea contact  110 . Each of the channels  112  may extend from at least a radius outside of the insert  102  to an internal edge of the cornea contact  110 , which may be close to the center area  106 . In some embodiments, the channels  112  may extend to at least an outside edge of the central cornea of the user&#39;s eye. In some embodiments, one or more of the channels  112  may extend radially outward and terminate at an edge of the enclosure  104 . While there are three channels  112  shown in  FIG. 1 , the number of channels and their symmetry is a non-limiting aspect. In general, it may be desirable to include an odd number of channels  112  so to ensure an open channel in case of symmetric physical characteristics of the eye close off channels that may align with such physical characteristics. For example, including an odd number of channels  112  may prevent the ophthalmic device  100  from aligning with any corneal astigmatism present in the wearer. 
     The enclosure  104  may additionally include one or more fenestrations  114 . Each of the fenestrations  114 , which may be holes or openings through the enclosure  104 , may be located at a radius outside of the insert  102 . The fenestrations  114  may extend from the anterior side of the enclosure  104  to intersect with a respective one of the channels  112  on the posterior side of the enclosure  104 . The fenestrations  114  may be from 100 to 1000 microns in diameter, for example. In some embodiments, the fenestrations  114  may be 400 to 500 microns in diameter. 
     A combination of the channels  112  and the fenestrations  114  may provide a pathway or conduit for the exchange of tear fluid between the tear fluid chamber and an area external to the ophthalmic device  100 . For example, tear fluid may propagate through one or more of the fenestrations  114  and their respective channels  112  to reach the tear fluid chamber, which may provide fresh tear fluid and oxygen to maintain ocular health. Conversely, old tear fluid may escape the tear fluid chamber through the channels  112  and fenestrations  114  while transporting mucus and debris away from the central cornea area. 
     The enclosure  104  may further include one or more offset features  116 . Each of the offset features  116  may be formed radially internal of the diameter of the insert  102 . The one or more offset features  116 , which may be non-rotationally symmetric, may be formed in the enclosure  104  to provide clearance between the insert  102  and the enclosure  104 . For example, the offset features  116  may provide around 100 microns of clearance between the insert  102  and the enclosure  104 . In some embodiments, the one or more offset features  116  may be formed in or on the anterior portion of the enclosure  104 , which may provide clearance between an anterior side of the insert  102  and an internal surface of the anterior portion of the enclosure  104 . Alternatively or additionally, the one or more offset features  116  may be formed in the posterior portion of the enclosure  104 , and provide clearance between an internal surface of the posterior portion of the enclosure  104  and the posterior side of the insert  102 . The one or more offset features  116  may also be alignment features that provide alignment in a direction normal to the ophthalmic device  100 , e.g., in the optical axis direction. In some embodiments, the one or more offset features  116  may be bumps formed in the enclosure  104 . 
     Further, the enclosure  104  includes one or more alignment features  118 . The one or more alignment features  118  may be formed radially outside of the diameter of the insert  102 . The one or more alignment features  118  may be formed in the enclosure  104  to provide alignment fiducials to aid in assembly of the ophthalmic device  100 . For example, the one or more alignment features  118  may provide radial alignment of the insert  102  to the enclosure  104  so to obtain centration of the insert  102 . In some embodiments, the one or more alignment features  118  may be formed in or on the anterior portion of the enclosure  104 . Alternatively or additionally, the one or more offset features  116  may be formed in the posterior portion of the enclosure  104 . In some embodiments, the one or more offset features  116  may be bumps formed in the enclosure  104 . 
     While  FIG. 1  shows three offset and alignment features  116  and  118 , respectively, the number of offset and alignment features is a non-limiting aspect of the present disclosure. In general, any number and/or arrangement of offset and alignment features that provide non-rotational symmetry me included in the ophthalmic device  100 . Additionally, any shape other than bumps is contemplated by the present disclosure, and the bumps example should not be considered limiting. 
     The skirt  108  may be an area or portion of the enclosure  104  that conforms to a user&#39;s eye outside of the cornea. The skirt  108  may anchor the ophthalmic device  100  in position, while allowing for movement and removal of the ophthalmic device  100 . For example, the skirt  108  may be flexible so that a user may be able to pinch it to remove the ophthalmic device  100  from their eye. Additionally, the skirt  108  may provide a gradual decrease in the thickness of the ophthalmic device  100  so to be more comfortable to the eye and to blinking of the eye. In some embodiments, the radius of curvature of the enclosure  104  in the skirt  108  area may be less than the radius of curvature of the enclosure  104  in the optic area  106 . 
       FIG. 2  is an illustrative cross-sectional view of an ophthalmic device  200  including posterior and anterior features in accordance with the present disclosure. The ophthalmic device  200  may be an example of the ophthalmic device  100 . The ophthalmic device  200  may be an on-eye wearable contact ophthalmic device, which may at least provide optical benefits to a wearer. 
     The illustrated embodiment of the ophthalmic device  200  includes an insert  202  disposed in an enclosure  204 . The enclosure  204  may include a cornea contact  210 , a plurality of channels  212 , a plurality of fenestrations  214 , and a plurality of offset features  216  (only one of which is shown). The various features may be similar to like features of the ophthalmic device  100 . The ophthalmic device  200  may have a concave side (facing down in  FIG. 2 ), and a convex side (facing up in  FIG. 2 ). The concave side may also be referred to as the posterior side, whereas the convex side may also be referred to as the anterior side. The ophthalmic device  200  may be worn on a user&#39;s eye, for example, with the concave side fitting onto the eye. 
     The plurality of offset features  216  may be formed on the convex side of the ophthalmic device  200 , and may provide clearance between the insert  202  and an internal surface of the enclosure  204 . The plurality of offset features  216 , which may be bumps formed in/on the anterior side of the enclosure  204 , may be formed inside the diameter of the insert  202 . Additionally, the plurality of offsets  216  may provide alignment features in the direction of the optical axis of the ophthalmic device  200 . While not shown in  FIG. 2 , the ophthalmic device  200  may further, at least in some embodiments, include a plurality of alignment features formed in the enclosure  204  and formed radially outside of the insert  202 , which may be similar to the one or more alignment features  118 . 
     The cornea contact  210  may provide a broken, or discontinuous, ring of contact area intended to contact a perimeter of a user&#39;s cornea. While the lined area shown in  FIG. 2  to show the location of the cornea contact  210  does not show breaks, the ring would be broken where each of the plurality of channels  212  occur, for example, and the cornea contact  210  may not contact the cornea in the breaks. The cornea contact  210  may be formed in or on the concave side of the enclosure  204  and formed under a perimeter area of the insert  202 . The cornea contact  210  may provide a buffer area for resting the ophthalmic device  200  on a user&#39;s eye, and may further improve the comfort of the ophthalmic device  200 . In some embodiments, the insert  202  may affect the comfort of the ophthalmic device  200 , so the cornea contact  210  may be disposed under the perimeter of the insert  202  to affect the comfort of the ophthalmic device  200 . The cornea contact  210  may be raised relative to the concave side of the ophthalmic device  200  inside the diameter of the cornea contact  210 , e.g., the optic area  206 . In some embodiments, the cornea contact  210  may not be raised outside of the perimeter of the insert  202 , and may instead blend into the skit  208 . This raised area may not contact the central cornea of the user&#39;s eye, which may provide clearance between the eye and the concave side of the optic area  206 , at least within the cornea contact  210  ring. The height of the clearance may allow the ophthalmic device  200  to fit a wide variety of eye shapes, a majority of the eye population for example. This volume of space formed between the cornea and the ophthalmic device  200  may form a tear fluid chamber, for example, and may hold tear fluid. 
     The plurality of channels  212  may be formed in or on the enclosure  204  and may extend through the cornea contact  210 . Each of the channels  212  may extend from a radius outside of the insert  202  radius to a radius internal of the insert  202  radius. For example, each of the channels  212  may extend from just outside of the insert  202  to an inner edge of the cornea contact  210 . In some embodiments, however, one or more channels  212  of the plurality of channels  212  may extend through the skirt  208  to an edge of the enclosure  204 . 
     The plurality of fenestrations  214  may extend through the enclosure  204  and intersect with a proximate end of a respective one of the plurality of channels  212 . Each of the plurality of fenestrations  214  may extend from the convex side to the concave side of the ophthalmic device  200 . On the concave side, the fenestrations  214  may couple to a respective one of the channels  212  so that an unobstructed path, e.g., a conduit, may be formed through the enclosure  204 . The plurality of fenestrations  214  may be formed outside of the insert  202 . 
     The combination of the plurality of channels  212  and the plurality of fenestrations  214  may form pathways/conduits between the tear fluid chamber and the eye external to the ophthalmic device  200 . The pathways may allow for the exchange of tear fluid between the tear fluid chamber and the eye external to the ophthalmic device  200  so to refresh the tear fluid in the tear fluid chamber to maintain ocular health while wearing the ophthalmic device  200 . 
     In some embodiments, the concave side of the enclosure  204  may have a different radius of curvature in the optic area  206  than in the skirt area  208 . Further, the concave side of the insert  202  may have a radius of curvature that is different than the corresponding radius of curvature of the enclosure  204 . The various radii of curvature, however, may desirably be formed so that the ophthalmic device  200  may fit a majority of the eye population. The clearance between the central cornea and the concave side of the ophthalmic device  200  due to the height of the cornea contact  210  may also affect the fit of the ophthalmic device  200 . 
       FIG. 3  is an illustrative cross-sectional view of a central area of an ophthalmic device  300  including posterior and anterior features in accordance with an embodiment of the present disclosure. The ophthalmic device  300  may be an example of the ophthalmic device  100 . The illustrated embodiment of the ophthalmic device  300  includes an insert  302  and an enclosure  304 . While the ophthalmic device  300  is not shown to include a skirt area, comparable to the skirt  108 , the skirt area is omitted to focus on various features in the central area of the ophthalmic device  300 . 
     A posterior side of the insert  302  may have a radius of curvature R 1 . R 1  may desirably be selected, based on a statistical analysis of a large population of eye shapes and sizes, to fit a majority of the eye population. Further, a posterior side of the enclosure  304  may have a radius of curvature R 2 . As with the insert, R 2  may desirably be selected, based on a statistical analysis of a large population of eye shapes and sizes, to fit a majority of the eye population. In some embodiments, R 1  and R 2  may allow the ophthalmic device  300  to fit greater than 95% of the eye population, for example. In some embodiments, R 1  and R 2  may be different. For example, R 1  may be around 8.5 mm whereas R 2  may be around 8 mm. 
     The enclosure  304  may include an offset feature  316  and an alignment feature  318 . The offset and alignment features  316  and  318 , respectively, may be bumps formed in or on an anterior side of the enclosure  304 . The offset features  316  may be formed inside of a diameter of the insert  302 , and may assist in alignment of the insert  302  and the enclosure  304  in a direction parallel to the optical axis of the ophthalmic device  300 . Further, the offset features  316  may form clearance between an anterior side of the insert  302  and an internal surface of the anterior side of the enclosure  304 . In some embodiments, the clearance may be around 100 microns, but other clearance amounts are within the scope of the present disclosure. 
     The alignment features  318  may be bumps formed in the posterior side of the enclosure  304 , and may be formed outside a diameter of the insert  302 . The alignment features  318  may provide alignment fiducials to aid assembly of the ophthalmic device  300 . In some embodiments, the alignment features  318  may cause centration of the insert  302  within the enclosure  304 . 
     The enclosure  304  may also include cornea contact  310 . Cornea contact  310  may be formed in/on the posterior side of the enclosure  304 , and may provide a cornea contact area. The cornea contact area may aid in comfort of the ophthalmic device  300  while being worn by a user. In some embodiments, the cornea contact  310  may be shaped into a discontinuous contoured profile, and arranged between a perimeter of the insert  302  and the surface of the eye. The height  326  of the cornea contact, at least with respect to a posterior side of the enclosure  304  within the cornea contact  310 , may provide clearance of the posterior side of the enclosure  304  within the cornea contact  310  and the eye. This clearance, which may range from 50 to 200 microns, may further allow the ophthalmic device to be worn by a majority of the eye population. The cornea contact  310  may further has a radius of curvature that may be in the range of a natural radius of curvature of a user&#39;s eye surface, e.g., it may mimic the cornea curvature in the area of contact, and may not be a feature on the posterior side of the enclosure  304  that excessively deforms the cornea, for example. Accordingly, the clearance created by the cornea contact  310  and the radius of curvature of the cornea contact  310  may add to the comfort of the ophthalmic device  300 . 
     The clearance between the eye and the posterior side of the enclosure  304  within the cornea contact  310  may further form a tear fluid chamber. The tear fluid chamber may be defined by the surface of the eye, the posterior side of the enclosure  304  and the cornea contact  310 . The tear fluid chamber may provide a volume for tear fluid to accumulate, which may provide for ocular health. While not shown in the ophthalmic device  300 , channels and fenestrations, similar to the channels  112  and fenestrations  114 , may be included in the enclosure  304 . The channels and fenestrations may provide a conduit for the exchange of tear fluid and oxygen between the tear fluid chamber and the eye external to the ophthalmic device  300 . The exchange of tear fluid may allow fresh tear fluid and oxygen to reach the central cornea area, while transporting mucus and debris away from the central cornea area. 
     While the cornea contact  310  is shown as a raised area of the enclosure  304 , in some embodiments only the side adjacent to the tear fluid chamber may be raised from the eye. In such an embodiment, the cornea contact  310  may blend into the enclosure  304  radially outward and continue to contact the eye in a direction toward the sclera. 
       FIG. 4  is an illustrative plan view of an ophthalmic device  400  including posterior and anterior features in accordance with an embodiment of the present disclosure. The ophthalmic device  400 , which may be similar to the ophthalmic device  100  in may aspects, may include various electronics to control a dynamic optic, for example. The illustrated embodiment of the ophthalmic device  400  includes an insert  402 , an enclosure  404 , control electronics  420  and  422 , and an antenna  424 . The ophthalmic device  400  may be an on-eye wearable device or an intraocular device, and may provide accommodation to a user, for example. 
     The insert  402  may be formed from soft or rigid biocompatible materials, and may be disposed within the enclosure  404 . The insert  402  may at least provide dynamic optical power to a user. For example, the insert  402  may include a dynamic optic based on liquid crystal or electrowetting techniques. The dynamic optic of the insert  402 , which may be arranged in the optic area  406 , may be controlled by the control electronics  420  and/or  422 , which may be included in or on a layer of the insert  402 . In some embodiments, the insert  402  may additionally include static optical power. The insert  402  may further be formed from a plurality of optical elements arranged into a stack, which may include a substrate for the control electronics  420 ,  422 , and the antenna  424 . 
     The control electronics  420  and  422  may include various logic, circuits, power supplies, and batteries for controlling the dynamic optic and for communication with components external to the ophthalmic device  400 . The antenna  424 , which may include multiple separate antennae in some embodiments, may be used to send and receive communication signals and/or for wireless charging of related batteries and or power supplies. 
     The disclosed embodiment of the enclosure  404  includes a cornea contact  410 , channels  412 , fenestrations  414 , offset features  416 , and alignment features  418 . These various features and geometries, which may be similar to like features and geometries of ophthalmic devices  100 ,  200  and  300 , may not be discussed in detail for sake of brevity. The offset features  416 , which may be bumps formed in/on an anterior side of the enclosure  404 , may form a clearance between the insert  402  and an internal surface of the enclosure  404 . Further, the offset features  416  may provide alignment in a direction normal to the optic area  406 . The alignment features  418 , which may be bumps formed in the anterior side of the enclosure  404 , may provide alignment fiducials to aid in centering the insert  402  within the enclosure  404 . 
     The cornea contact  410  may be a discontinuous ring formed in or on a posterior side of the enclosure, and disposed under a perimeter of the insert  402 . The cornea contact  410  may provide vault to the optic area  406 , which may form a clearance over a user&#39;s central cornea area. This clearance may form a volume of space, such as the tear fluid chamber discussed above. 
     The channels and fenestrations  412  and  414 , respectively, may be formed in the enclosure  404 . For example, the channels  412  may be formed on the posterior side of the enclosure  404  and may extend through the cornea contact  410 , which may form the discontinuous portions of the cornea contact  410 . The channels  412  may extend from a radius outside of the insert  402  to at least an inner radial edge of the cornea contact  410 . Additionally, the channels  412  may intersect with, e.g., couple to, respective ones of the fenestrations  414  radially outside of the insert  402 . The channels and fenestrations  412  and  414 , respectively, may combine to form a conduit for the exchange of tear fluid between the tear fluid chamber and the eye external to the ophthalmic device  400 . In some embodiments, one or more of the channels  412  may extend to an outer edge of the enclosure  404 , which may or may not intersect with a fenestration  414 . 
     The skirt  408  may provide a soft area outside of the insert  402  that may promote ease of removal of the ophthalmic device  400 . For example, the skirt  408  may be pinched by a user when removing the ophthalmic device  400 . Additionally, the channels and fenestrations  412  and  414 , respectively, may assist with removal by preventing the occurrence of suction of the ophthalmic device  400  onto the user&#39;s eye. 
       FIG. 5  is a functional block diagram of an ophthalmic device  500  including posterior and anterior features in accordance with an embodiment of the present disclosure. Ophthalmic device  500  may be an on-eye device, such as a contact lens or a smart contact lens, or an implantable device, such as an intraocular lens. In the depicted embodiment, ophthalmic device  500  includes an enclosure material  510  formed to be either contact-mounted to a corneal surface of an eye or implanted into an eye. The enclosure material  510  may be one implementation of the enclosure  104 . A substrate  515  is embedded within or surrounded by enclosure material  510  to provide a mounting surface for a power supply  520 , a controller  525 , an antenna  540 , and various interconnects  545  and  550 . The substrate  515  and the associated electronics may be one implementation of the control electronics  420  and/or  422 . Additionally, the substrate  515  may be included with the insert  402 , such as on a perimeter area of the insert  402 . The illustrated embodiment of power supply  520  includes an energy harvesting antenna  555 , charging circuitry  560 , and a battery  565 . The illustrated embodiment of controller  525  includes control logic  570 , accommodation logic  575 , and communication logic  580 . As shown, accommodation actuator  530  is disposed in the enclosure material  510 . 
     Power supply  520  supplies operating voltages to the controller  525  and/or the accommodation actuator  530 . Antenna  540  is operated by the controller  525  to communicate information to and/or from ophthalmic device  500 . In the illustrated embodiment, antenna  540 , controller  525 , and power supply  520  are disposed on/in substrate  515 , while accommodation actuator  530  is disposed in enclosure material  510  (not in/on substrate  515 ). However, in other embodiments, the various pieces of circuitry and devices contained in ophthalmic device  500  may be disposed in/on substrate  515  or in enclosure material  510 , depending on the specific design of ophthalmic device  500 . For example, in one embodiment, accommodation actuator  530  may be disposed on a transparent substrate. 
     Substrate  515  includes one or more surfaces suitable for mounting controller  525 , power supply  520 , and antenna  540 . Substrate  515  can be employed both as a mounting platform for chip-based circuitry (e.g., by flip-chip mounting) and/or as a platform for patterning conductive materials (e.g., gold, platinum, palladium, titanium, copper, aluminum, silver, metals, other conductive materials, combinations of these, etc.) to create electrodes, interconnects, antennae, etc. In some embodiments, substantially transparent conductive materials (e.g., indium tin oxide or silver nanowire mesh) can be patterned on substrate  515  to form circuitry, electrodes, etc. For example, antenna  540  can be formed by depositing a pattern of gold or another conductive material on substrate  515 . Similarly, interconnects  545  and  550  can be formed by depositing suitable patterns of conductive materials on substrate  515 . A combination of resists, masks, and deposition techniques can be employed to pattern materials on substrate  515 . Substrate  515  can be a relatively rigid material, such as polyethylene terephthalate (“PET”), parylene or another material sufficient to structurally support the circuitry and/or electronics within enclosure material  510 . Ophthalmic device  500  can alternatively be arranged with a group of unconnected substrates rather than a single substrate  515 . For example, controller  525  and power supply  520  can be mounted to one substrate  515 , while antenna  540  is mounted to another substrate  515  and the two can be electrically connected via interconnects. Substrate  515  may also be a continuous piece of semiconductor, housing all or some of the aforementioned pieces of device architecture as integrated circuitry. 
     Substrate  515  can be shaped as a flattened ring with a radial width dimension sufficient to provide a mounting platform for the embedded electronic components. Substrate  515  can have a thickness sufficiently small to allow substrate  515  to be embedded in enclosure material  510  without adversely influencing the profile of ophthalmic device  500 . Substrate  515  can have a thickness sufficiently large to provide structural stability suitable for supporting the electronics mounted thereon. For example, substrate  515  can be shaped as a ring with a diameter of about 10 millimeters, a radial width of about 1 millimeter (e.g., an outer radius 1 millimeter larger than an inner radius), and a thickness of about 50 micrometers. Substrate  515  can optionally be aligned with the curvature of the eye-mounting surface of ophthalmic device  500  (e.g., convex surface). For example, substrate  515  can be shaped along the surface of an imaginary cone between two circular segments that define an inner radius and an outer radius. In such an example, the surface of substrate  515  along the surface of the imaginary cone defines an inclined surface that is approximately aligned with the curvature of the eye mounting surface at that radius. 
     In the illustrated embodiment, power supply  520  includes a battery  565  to power the various embedded electronics, including controller  525 . Battery  565  may be inductively charged by charging circuitry  560  and energy harvesting antenna  555 . In one embodiment, antenna  540  and energy harvesting antenna  555  are independent antennae, which serve their respective functions of energy harvesting and communications. In another embodiment, energy harvesting antenna  555  and antenna  540  are the same physical antenna that are time shared for their respective functions of inductive charging and wireless communications with reader  505 . Additionally or alternatively, power supply  520  may include a solar cell (“photovoltaic cell”) to capture energy from incoming ultraviolet, visible, and/or infrared radiation. Furthermore, an inertial power scavenging system can be included to capture energy from ambient vibrations. 
     Charging circuitry  560  may include a rectifier/regulator to condition the captured energy for charging battery  565  or directly power controller  525  without battery  565 . Charging circuitry  560  may also include one or more energy storage devices to mitigate high frequency variations in energy harvesting antenna  555 . For example, one or more energy storage devices (e.g., a capacitor, an inductor, etc.) can be connected to function as a low-pass filter. 
     Controller  525  contains logic to choreograph the operation of the other embedded components. Control logic  570  controls the general operation of ophthalmic device  500 , including providing a logical user interface, power control functionality, etc. Accommodation logic  575  includes logic for receiving signals from sensors monitoring the orientation of the eye, determining the current gaze direction, focal distance of the user and/or relative position of the eyelid, and manipulating accommodation actuator  530  (focal distance of the contact lens) in response to these physical cues. The auto-accommodation can be implemented in real-time based upon feedback from gaze tracking, or permit the user to select specific accommodation regimes (e.g., near-field accommodation for reading, far-field accommodation for regular activities, etc.). Communication logic  580  provides communication protocols for wireless communication with reader  505  via antenna  540 . In one embodiment, communication logic  580  provides backscatter communication via antenna  540  when in the presence of an electromagnetic field  571  output from reader  505 . In one embodiment, communication logic  580  operates as a smart wireless radio-frequency identification (“RFID”) tag that modulates the impedance of antenna  540  for backscatter wireless communications. The various logic modules of controller  525  may be implemented in software/firmware executed on a general purpose microprocessor, in hardware (e.g., application specific integrated circuit), or a combination of both. 
     Ophthalmic device  500  may include various other embedded electronics and logic modules. For example, a light source or pixel array may be included to provide visible feedback to the user. An accelerometer or gyroscope may be included to provide positional, rotational, directional or acceleration feedback information to controller  525 . 
     The illustrated embodiment also includes reader  505  with a processor  582 , an antenna  584 , and memory  586 . Memory  586  in reader  505  includes data storage  588  and program instructions  590 . As shown reader  505  may be disposed outside of ophthalmic device  500 , but may be placed in its proximity to charge ophthalmic device  500 , send instructions to ophthalmic device  500 , and/or extract data from ophthalmic device  500 . In one embodiment, reader  505  may resemble a conventional contact lens holder that the user places ophthalmic device  500  in at night to charge, extract data, clean the lens, etc. 
     External reader  505  includes an antenna  584  (or group of more than one antennae) to send and receive wireless signals  571  to and from ophthalmic device  500 . External reader  505  also includes a computing system with a processor  582  in communication with a memory  586 . Memory  586  is a non-transitory computer-readable medium that can include, without limitation, magnetic disks, optical disks, organic memory, and/or any other volatile (e.g., RAM) or non-volatile (e.g., ROM) storage system readable by the processor  182 . Memory  586  can include a data storage  588  to store indications of data, such as data logs (e.g., user logs), program settings (e.g., to adjust behavior of ophthalmic device  500  and/or external reader  505 ), etc. Memory  586  can also include program instructions  590  for execution by processor  582  to cause the external reader  505  to perform processes specified by the instructions  590 . For example, program instructions  590  can cause external reader  505  to provide a user interface that allows for retrieving information communicated from ophthalmic device  500  or allows transmitting information to ophthalmic device  500  to program or otherwise select operational modes of ophthalmic device  500 . External reader  105  can also include one or more hardware components for operating antenna  584  to send and receive wireless signals  571  to and from ophthalmic device  500 . 
     External reader  505  can be a smart phone, digital assistant, or other portable computing device with wireless connectivity sufficient to provide the wireless communication link  571 . External reader  505  can also be implemented as an antenna module that can be plugged into a portable computing device, such as in an embodiment where the communication link  571  operates at carrier frequencies not commonly employed in portable computing devices. In some instances, external reader  505  is a special-purpose device configured to be worn relatively near a wearer&#39;s eye to allow the wireless communication link  571  to operate with a low power budget. For example, the external reader  505  can be integrated in a piece of jewelry such as a necklace, earing, etc. or integrated in an article of clothing worn near the head, such as a hat, headband, etc. 
     The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. 
     These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.