Patent Description:
Glaucoma is a condition resulting in increased pressure within the eye that eventually leads to damage of the optic nerve dtat transmits images to the brain, which results in gradual vision loss. The increased pressure within the eye causes a loss of retinal ganglion cells in a characteristic pattern of optic neuropathy. A patient suffering from glaucoma typically experiences a build-up of aqueous fluid which increases the pressure inside the eye (i.e. intraocular pressure). Elevated IOP is one of the primary risk factors for developing glaucoma, which must be carefully monitored and controlled in treating glaucoma. As retinal ganglion cells are damaged by glaucoma, the visual signals from at least a portion of visual field arc no longer reported to the brain, forming blind spots or scotomas. As glaucoma progresses and increasingly damages more nerve tissue in the optic nerve, vision loss continues as the scotomas increase in size and/or number. Failure to properly treat glaucoma and to reduce and monitor the IOP may cause irreversible vision loss. Untreated glaucoma, which affects one in <NUM> people under the age of fifty and <NUM>% of those over the age of <NUM>, is the second leading cause of blindness worldwide. As of <NUM>, about <NUM> million people suffer from glaucoma world-wide and it is estimated that, by <NUM>. about <NUM> million people will suffer from glaucoma. In addition, since a high percentage of people are over the age of <NUM> years old, and as the world-population ages and life-spans increase, it is expected that glaucoma patient populations will continue to increase.

IOP in a healthy human eye is generally between <NUM> mmHg and <NUM> mmHg. Glaucoma causes substantial increase in and/or variation in IOP than that experienced in a healthy eye. The IOP is determined largely by the amount of aqueous fluid entering and exiting the eye. Aqueous fluid is produced by the ciliary body to supply the lens and cornea with nutrients and carry away waste products. Normally, aqueous fluid flows between the iris and the lens. through the pupil and to the drainage angle before exiting the eye through a tissue called the trabecular meshwork in the drainage angle, including the scblemm's canal. If the aqueous fluid is produced at a rate faster than it drains, then the intraocular pressure will rise. An elevated intraocular pressure is associated with two major types of glaucoma: open-angle glaucoma and closed-angle glaucoma. In open-angle glaucoma, the drainage angle between the cornea and the iris is open and allows the aqueous fluid of the eye to reach the trabecular meshwork, but abnormalities in the trabecular meshwork reduce the outflow of aqueous fluid from the eye. In closed-angle glaucoma, obstructions within the trabecular meshwork prevent the aqueous fluid from draining properly out of the eye.

While the progression of glaucoma can be substantially halted in many patients using a variety of treatments, for example, medicines, prescription eye drops, shunts, and surgical procedures, failure to properly diagnose and/or monitor the lOP of a patient can drastically reduce the effectiveness of available treatments. Currently, glaucoma monitoring often uses infrequent IOP measurements obtained by a physician at a medical facility. For example, a typical patient may have their IOP measured on average four to six times per year by non-invasive techniques, such as tonometry. While ionometry techniques are generally low cost easy, and non-invasive, a number of different types of errors can significantly reduce the accuracy of this diagnostic tool and as such potentially result in inappropriate diagnosis and/or ineffective follow-up medical treatment.

For example, at least some of these non-invasive clinical techniques may not detect elevated IOP levels (e.g.. pressure spikes) as only a single point measurement is taken during an eye exam. Failure to continuously and/or frequently monitor IOP levels outside the eye clinic (e.g.. more than four to six measurements per year) may lead to inaccurate detection of the patient's real IOP profile (e.g., real IOP may be higher or lower than measured IOP). Non-invasive measurements in some instances lack accuracy as these devices measure pressure of the eye with an external sensor that provides an indirect measurement of the actual pressure inside the eye and are unable to capture the dynamic state of the disease in which there is a continuously changing IOP at low and high frequency rates with up to <NUM>,<NUM> spikes per hour. For example, factors that affect accuracy may include failure to account for anatomical differences, such as a patient's cornea thickness, scleral rigidity, or conical curvature, variances due to operator's use or technique, physiological influences, such as caffeine or alcohol use. or prior refractive surgery that may affect a patient's IOP. etc. Hence, the indirect IOP measurements from such non-invasive devices may differ from the actual IOP inside the eye (e.g., overestimated or underestimated) which may lead to inappropriate diagnosis and/or follow-up treatment. Further, it is often inconvenient and impractical for patients to visit the eye clinic on a strict regular schedule for repeated IOP measurements.

Although implantable IOP devices have been proposed for direct IOP measurements on a daily basis, these first generation implants may also suffer from several drawbacks which in turn may result in indirect and/or inaccurate measurement of IOP and inappropriate medical treatment of glaucoma. For example, the IOP devices may be too large or bulky in dimension, size or shape to be safely and effectively placed entirely within a desired location or structure of the eye for direct measurement of IOP. Further, some devices may be extremely invasive, requiring major surgery for implantation and/or complicated positioning of multiple components which are each implanted in different structures or areas of the eye, which unnecessarily increases patient risk and/or injury and total healthcare costs.

Further, some IOP implantable devices may utilize pressure ports which are susceptible to sensing inaccuracies or require direct implantation within certain anatomical locations, such as the anterior chamber, posterior chamber, suprachoroidal space, or cornea of the eye which may lead to unanticipated complications. Also, some of these devices may not be well suited for chronic implantation due to IOP implant design issues of water ingress and/or thermal stress (e.g., associated with polymer packaging), which in turn precludes continuous monitoring of IOP. Such proposed flexible sensors also have issued of degraded stability. In some instances, some IOP devices also suffer from poor calibration and/or monitoring is not adjustable so as to further result in inaccurate IOP detection levels.

Accordingly, it would be desirable to provide improved implant devices and methods of implantation that overcome at least some the above mentioned shortcomings, In particular, it would be desirable to develop ultra-miniature implantable IOP devices that accurately, continuously, and adjustably monitor IOP levels. Ideally, such devices should directly measure IOP pressure levels and can be safely and effectively implanted entirely within a desired location within the eye quickly and easily in an outpatient environment, such as the physician's office. without invasive major surgery. Such devices should further allow for chronic implantation so as to provide long-term stable and continuous IOP measurement profiles for appropriate diagnosis and follow-up therapy. In addition, there exists a need for improved methods of implantation for such devices within the eye that do not require surgical intervention and avoid damage to the sensitive structures of the eye.

<CIT> describes an implantable intraocular physiological sensor for measuring intraocular pressure, glucose concentration in the aqueous humor, and other physiological characteristics. The implantable intraocular physiological sensor may be at least partially powered by a fuel cell, such as an electrochemical glucose fuel cell. The implantable intraocular physiological sensor may wirelessly transmit measurements to an external device. In addition, the implantable intraocular physiological sensor may incorporate aqueous drainage and/or drug delivery features.

<CIT> describes methods of implanting an intraocular pressure sensor and systems for sensing intraocular pressure. An intraocular pressure sensor, including a top surface, may be placed through the sclera of an eye of a patient. The intraocular pressure sensor may be caused to be inserted into the sclera until the top surface of the intraocular pressure sensor is substantially flush with the exterior wall of the sclera. An implantation wand may be used to assist in the insertion process. The wand may be disengaged from the intraocular pressure sensor after it has been implanted.

Disclosed herein are devices and methods for implanting an IOP sensor within the eye of a patient. in one aspect, such methods include injecting a sensor device within the eye to provide improved sensing and/or monitoring of ΣDF for use in glaucoma treatments.

Since the mechanisms contributing to the increase in intra-ocular pressure occur within the anterior chamber or adjacent thereto, conventional methods generally focus on measuring intraocular pressure within the anterior chamber. Because the anterior chamber is a particularly sensitive region. great care must be taken to avoid contacting the various parts of the anterior chambers, which may result in damage to the delicate structures therein and degrade visual function. in one aspect, the present disclosure relates to measuring IOP of the eye by measuring pressure within the vitreous body. Since the pressure within the anterior chamber pushes against and increases the pressure within the vitreous body, measurement of pressure within the vitreous body provides a relatively accurate pressure measurement of IOP of the eye. In certain aspects, the methods of measuring IOP include positioning a pressure sensor within the vitreous body such that the entire pressure-sensing membrane of the pressure sensor is maintained within the vitreous body. In one aspect, the lOP measurement of pressure within the vitreous body may be compared to and correlated with a pressure within the anterior chamber, which may be measured according to various other independent measurement methods. This comparison or correlation can determine any degradation or attenuation of the intraocular pressure, if any, as it is transmitted from the anterior chamber to the vitreous body. Studies suggest that pressure between the anterior and posterior chamber may equalize such that a change in pressure in the anterior chamber will be reflected in the posterior chamber with a slight time delay. Monitoring the anterior chambers directly is not worth the risk of affecting vision significantly or the associated liability. Even if there were a slight degradation or attenuation in IOP when measuring within the vitreous humour, the increased pressure may be detected with a continuous pressure profile that will satisfactorily quantify the increase in pressure in the anterior chamber. The proposed measurement locations can be readily validated across a range of animal models, which may also be used to adjust the sensor sensitivity if necessary. The actual pressure of interest is the pressure seen by the optical nerve head (ONH) which is the pressure that, if excessive, leads to apoptosis or death of retinal ganglion cells and axons.

In certain aspects, methods of implanting an lOP sensor within the eye include penetrating a distal tip of an injector or syringe through a conjunctiva and a sclera of the eye into the vitreous body and injecting the IOP sensor through the distal tip of the injector or syringe. Positioning the TOP sensor may include distally advancing the distal tip of the injector or syringe until a distal facing surface of the injector or syringe abuts against the conjunctiva. In some embodiments, the sensor device has a maximum thickness and width of about <NUM> microns or less to facilitate injection through a needle having a gauge of <NUM> or higher (e.g. <NUM> or <NUM> gauge) along an insertion axis in-plane with the sensor device.

In embodiments in which the sensor device is injected with a fluid filled syringe, methods may include positioning the injector or syringe within or near an ora serrata region of the eye, for example the pars plana region in between the ora serrata and limbus, prior to penetrating the distal tip of the injector or syringe so as to avoid any optic structures of a retina of the eye. In some embodiments, the syringe may be positioned along the pars planar. In some embodiments, a fluid is injected into the conjunctiva prior to penetrating the distal tip of the injector or syringe, thereby creating a ballooned portion of the conjunctiva in the ora serrata region. The fluid may include an anesthetic to reduce sensitivity in the eye of the patient prior to penetrating the sclera with the distal tip of the injector or syringe. Typically, the distal tip of the injector or syringe is then offset by a small distance, such as about <NUM> nun or less, before penetrating the sclera. The ballooned portion facilitates deployment of the anchor along the sclera and covering of a proximal end of the device with the conjunctiva after implantation. Methods may further include releasing the IOP sensor from the syringe by displacing a fluid within the syringe. This release may be effected by proximally retracting the distal tip into the syringe. This approach allows the user to stabilize a position of the IOP sensor within the vitreous body during release from the syringe.

In some embodiments, methods of implantation include penetrating partly through a sclera of die eye with an instrument and advancing the IOP sensor into the partly penetrated sclera so as to complete penetration of the sclera with a distal tip of the IOP sensor. In some embodiments, this allows the release of the IOP sensor without penetrating the distal tip of a needle of the syringe through the sclera. For example, the distal tip may be inserted only partly into the sclera before advancement of the IOP sensor causes the IOP sensor device to penetrate through the remainder of the sclera and into the vitreous body. Such embodiments may include a distally tapered tip on the sensor device of sufficient strength and stiffness to penetrate through the sclera or at least a portion thereof. In some embodiment, die distal penetrating tip may be formed within a same layer or substrate as the one or more anchoring members formed at a proximal end of the sensor device. In other embodiments, the distal penetrating tip may be included within an outer casing, housing or "boat" structure that extends at least partly about the IOP sensor device.

In another aspect, methods of implantation further include anchoring of the sensor device within the eye by deploying one or more anchoring members against the sclera. The one or more anchoring members may be defined so as to be resiliently biased to extend laterally outward relative to the insertion axis. The outwardly extending anchors may be sufficiently flexible to be bent toward the insertion axis and constrained within the distal tip of the syringe when injected. Upon release from the distal tip of the syringe, the anchoring members are deployed proximally of the sclera so as to engage an outer surface of the sclera to inhibit movement of the lOP sensor further into the cortical vitreous body vitreous body at the periphery of the posterior chamber and away from retina and ciliary body.

In one aspect, the one or more anchoring members and the IOP sensor are defined portions of a wafer or substrate of the sensor device. At least a portion of the IOP sensor may include a MEMs device formed by a wafer process. In such embodiments, anchoring may include engaging the sclera with the one or more anchoring members that are resiliently deflectable in a direction in-plane with the wafer in which the anchors are formed. In another aspect, the anchoring members may include one or more expandable mechanical features such as memory shaped alloy (e.g. Nitinol loop) that is clamped into a silicon wafer of the sensor device or may include a polymer expandable mechanical layer in the device.

In still other embodiments, the sensor device may include at least a first and second anchoring member such that anchoring includes deploying the first anchoring member along the sclera outside of the vitreous body and deploying the second anchoring member along the sclera inside the vitreous body so as to inhibit axial movement of the IOP sensor along die insertion axis in both proximal and distal directions after implantation. Each of the first and second anchoring members may include one or more anchoring members. In another aspect, anchoring against rotation of the sensor device may be provided by the shape of the sensor device itself. For example, in some embodiments, the sensor device may be formed with a cross-sectional shape that is not axi-symmetric along a longitudinal axis of the sensor device, for example, a square or rectangular cross-section, so as to inhibit rotation of the device along its longitudinal axis. This feature allows for improved charging and telemetry by allowing the user to stabilize the position at which the charging and telemetry components of the sensor device are positioned.

In another aspect, methods for extracting the implanted sensor device are provided. Such methods may include extracting the IOP sensor by attaching an instrument to an extraction feature coupled to a proximal end of the IOP sensor disposed outside the vitreous body. In an embodiment where the sensor device has first and second anchors, extraction may include pulling the extraction feature until an anchoring force provided by the at least second anchoring member is overcome.

Methods of anchoring an implant are also provided. Such methods may include inserting an implantable device through a distal tip of an injector or syringe along an insertion axis into a body tissue or body space within a patient, the device being formed, at least in part, by a wafer process and deploying one or more anchoring members of the device so as to extend laterally outward from the insertion axis to inhibit movement of the implanted device within the body tissue or body space. The one more anchoring members may include a portion of a wafer of the device defined so as to be resiliently deflectable in a direction in-plane with the wafer. Inserting the implantable device may include constraining the one or more anchoring members within the distal tip or a sheath in a position deflected toward die insertion axis, the insertion axis being in-plane with the wafer defining the one or more anchoring members. Deploying the one or more anchoring members may include releasing the one or more anchoring members from the constraining distal tube or sheath when the device is positioned in a desired position within the body tissue space. The sensor may be positioned within a target region in the patient in which a physiological measurement is desired by injecting the sensor into the target region so that the entire sensor portion is disposed within the region. In some embodiments, the method may include penetrating a distal tip of an injector or syringe through a tissue wall of the patient along an insertion axis, wherein the sensor is injected through the distal tip of the injector or syringe. Such injectable sensors may include any of the features described herein and may be implanted, anchored or extracted according to any of the methods set forth herein.

<FIG> is an overview illustration of a sensor implantation method. In particular, the depicted method relates to implantation of an lOP sensor device <NUM> within an eye <NUM> of a patient by injecting the TOP sensor device <NUM> into the eye with a fluid-filled syringe <NUM> or injector. In one aspect, the IOP sensor device is positioned within the vitreous body of the eye <NUM> by penetrating the conjunctiva and sclera with a distal tip of a needle of a syringe <NUM> along insertion axis I extending through the ora serreta region. Implanting the sensor device by injection at this location is advantageous over conventional implantation methods as it avoids the potential for damaging the delicate structures within the anterior chambers and as well as damage to the photo-sensitive tissues of the retina.

In one aspect, the injectable sensor can be implanted in a physician's office without surgery, such as by a relatively simple injection procedure using a standard needle size (e.g. <NUM> gauge). Once implanted the sensor device can provide continuous monitoring, up to one week or several weeks between charges. The system may include an external patient data acquisition unit that is used to charge the implanted sensor, collect and store data from the implanted sensor, and transmit the collected IOP data to a data server for further analysis and monitoring (e.g. the cloud or other server). The data may be available to the patient and/or the patient's treating physician at any time. The external patient data acquisition unit may be incorporated into a personal mobile device, such as a smart-phone. These aspects are further described in U. Non-Provisional Patent Application Serial No. (Attorney Docket No. <NUM>-<NUM>) entitled "Ultra Low Power Charging Implant Sensors with Wireless Interface for Patient Monitoring.

<FIG> illustrate sequential steps of a method of implanting an IOP sensor within a vitreous body of an eye <NUM> in accordance with the approach described above in <FIG>. As shown in <FIG>. a fluid is injected into the conjunctiva <NUM> in the ora serrata region of the eyeball to form a ballooned portion <NUM> of the conjunctiva. The fluid may be saline and/or may include a numbing or anesthetic to reduce sensitivity in the eye <NUM> prior to penetrating the layers of the eye during implantation. The conjunctiva is the mucous membrane that lines the inner surface of the cyclids and is continued over the forepart of the eyeball. The ballooned portion facilitates deployment of the sensor device against the sclera and allows the conjunctiva to cover the proximal anchoring portion of the sensor device after implantation. as will be described in further detail below.

As shown in <FIG>, a distal tip <NUM> of the fluid-filled syringe or injector <NUM> is penetrated through the ballooned portion <NUM> of the conjunctiva and through the sclera <NUM> and the choroid <NUM> until the distal tip <NUM> is positioned within the vitreous body <NUM>. The sclera <NUM> is the dense fibrous opaque white outer coat enclosing the eyeball except the part covered by the cornea (not shown), while the choroid <NUM> is the vascular layer extending between the retina <NUM> and the sclera <NUM> to the ciliary body and iris (not shown) of the eye <NUM>. The IOP sensor <NUM> is disposed within the distal tip <NUM> of the fluid-filled syringe and may include one or more anchoring members <NUM> constrained within the distal tip to be deployed upon release (e.g., self-expanding). The distal tip <NUM> is advanced distally along the insertion axis until a distal facing surface of the syringe <NUM> abuts against the ballooned portion <NUM>. The distal tip <NUM> is then retracted into the syringe <NUM> such that displacement of fluid within the syringe causes the sensor device <NUM> to maintain its position while the distal tip <NUM> is retracted, thereby releasing the sensor device from the syringe or injector <NUM>.

A shown in <FIG>, after release from the distal tip <NUM> of the syringe <NUM>, the anchoring members <NUM> resiliently extend laterally outward from the insertion axis against the outer surface of the sclera <NUM>. This anchoring configuration substantially maintains the position of the sensor diaphragm s of the device <NUM> at the desired location so that an IOP sensor near a distal end of the sensor device remains entirely within the vitreous body. such as shown in <FIG> and <FIG>. By extending the anchoring members along the sclera outside the vitreous body, the anchoring members <NUM> prevent the sensor device <NUM> from potentially slipping into the vitreous body, which could cause damage to the retina or optic nerve <NUM>.

<FIG> shows the sensor device <NUM> implanted within the eye. In certain aspects, the sensor device <NUM> is configured such that a particular alignment (e.g. rotational) is not required to facilitate charging and/or wireless communication with the device. For example, so long as the sensor device <NUM> is implanted into the eye so that the sensor s is disposed within the targeted region and the sensor device <NUM> is anchored near the sclera. the charging and communication coils are in close enough proximity such that an external device positioned near the eye can establish sufficient magnetic coupling so as to charge and/or communicate with the device. Nonetheless, in another aspect, for certain configurations, it may be useful to provide methods that control alignments/orientation for the sensor device when implanted for various reasons, such as to optimize charging or improve communication. In such cases, the orientation of the can be controlled by providing the sensor device in a substantially fixed or at least a known orientation within the distal tip such that controlling the orientation of the syringe or injector during implantation controls orientation of the sensor <NUM>. For example, if die sensor orientation is known, the syringe can be marked (e.g. a line or arrow) so that the physician can visually align the syringe in a desired location to control orientation of the implanted sensor device <NUM>.

<FIG> illustrate an example sensor device <NUM> having two anchoring members at a proximal end thereof, which have a bias in a lateral direction. As shown in <FIG>, the anchoring members <NUM> extend laterally outward from an insertion axis i along which the sensor <NUM> is implanted. Although the anchoring members are shown as extending substantially perpendicular to the insertion axis, it is appreciated that the anchoring members could configured to extend along other angles (e.g. <NUM>, <NUM> or <NUM> degrees from the insertion axis) according to a desired anchoring configuration or as needed for a particular application. In one aspect, the sensor device is formed, at least in part, using wafer processing methods, such that the anchoring members may be defined as features of a wafer or substrate of the sensor device. For example, the sensor device may be formed on a silicon substrate and the anchoring members may be defined as features of the silicon substrate using wafer processing methods, such as deep etching. In addition, various wafer fabrication methods may be used to round or soften any sharp comers of the sensor device to avoid damage to eye tissues after implantation.

In one aspect, the sensor device is formed, at least in part, on a rigid substrate, such as a silicon wafer. Although the substrate may be substantially rigid, portions of the substrate, such as those portions defining the one or more anchoring members, may be processed so as to alter a mechanical property as desired. For example, a wafer processing method may be used to define the anchoring members with a desired thickness and/or width so that the anchoring members become semi-rigid or flexible. This allows the one or more anchoring members to be sufficiently flexible in a direction in-plane with the device so as to bend alongside the sensor device when constrained within a distal tip of a needle, such as shown in <FIG>. Preferably the sensor device is sufficiently small enough to be injected through a needle (e.g. gage of <NUM> or higher) along a direction in-plane with sensor device. Once the distal tip <NUM> of the syringe is retracted, the anchoring members <NUM> resiliently return to their laterally extended configuration, as shown in <FIG>, so that when pushed distally along the insertion axis, the anchoring members engage an outer surface of the sclera. thereby preventing further distal movement of the sensor device. In one aspect, the conjunctiva covers and heals over the proximal surface of the sensor device such that the conjunctiva inhibits movement of the implanted sensor device in the proximal direction while the anchoring members inhibit movement of the implanted sensor in the distal direction.

<FIG> illustrates a detail view of a sensor device <NUM> having two resiliently deflectable anchoring members <NUM> at a proximal end of the device <NUM>. which are constrained within the distal tip <NUM> of the syringe or injector. <FIG> illustrates a cross-sectional view of the sensor device of <FIG> constrained within the distal tip <NUM> of the syringe. As can be seen, the sensor device <NUM> comprises a vertically-stacked device formed, at least in part using wafer fabrication methods. The anchoring members <NUM> may be formed from a portion of a rigid substrate, such as a silicon wafer. Typically, the anchor is defined its own substrate material separate from the MEMS pressure sensor wafer. In one aspect, a MEMs device is supported on a rigid substrate that defines at least a part of the sensor. Forming the sensor on a rigid substrate may improve the integrity, accuracy and longevity of the MEMs device. while defining various other portions of the rigid substrate to be flexible allows for improved anchoring and/or deployment as needed for a given application. While a certain configuration of sensor, in particular a sensor having a vertically stacked architecture, it is appreciated that various other configurations may be utilized in accordance with the implantation methods described herein. For example, the device may include a vertically stacked architecture such as those shown in <FIG> of U. Non-Provisional Patent Application Serial No. (Attorney Docket No. <NUM>-<NUM>) entitled "Hermetically Sealed Implant Sensors with Vertical Stacking Architecture. " filed concurrently herewith.

In certain aspects, the anchoring members are defined in a portion of the wafer that is thinned down (e.g. thinned to a <NUM> range) and that passes all electrical connections using TSV (through silicon vias). The electrical connections are scaled from the body fluid/media using a seal ring similar to the one used between MEMS wafer and CMOS wafer. The portion extending through the die area that will define the anchoring members will extend and typically etched using a process called DRIE to create the desired shape. This process may be done when all the wafers are bonded together so as to process them in a batch mode. The anchoring members are formed such that they are extended when the wafers are stacked, which creates a fairly wide spacing between each die. In one aspect, before dicing, all edges are rounded with a wet etch (isotropic) to create soft corners and avoid sharp edges that may need to be eliminated to reducing tissue damage. To facilitate the dicing, the anchors are typically pre-etched (DRIE) and formed before the interposer is bonded. After the stack (CSP) is created via bonding, the dicing will cingulated each die but they will be left on blue-tape for pick and place. Each die with extended anchoring members is pushed into the syringe such that the anchoring members fold against the sidewall of the syringe. The angle and length of the anchoring members determines how much anchoring force the anchoring members provide against the tissue. In some configurations, the anchoring members are formed to provide an anchoring force within a range of <NUM> to <NUM>,<NUM>µN. It is appreciated that while such configurations are particularly useful for anchoring of the described sensor device <NUM> within the eye, various other configurations of anchoring members may be utilized, including anchoring members with sharpened edges (e.g. barbs), so as to facilitate anchoring within various other tissues. Such configuration may be particularly useful in sensor devices implanted in various other locations within the human body.

<FIG> depict a syringe <NUM> or injector used in accordance with the sensor implantation methods described above. The syringe <NUM> may include an outer cylinder having a distal facing surface <NUM> and an inner cylinder <NUM> slidably disposed within. The syringe <NUM> may be provided to a surgeon pre-sterilized and pre-filled with a fluid and a sensor device fixed within the distal tip <NUM> of the syringe. The sensor device <NUM> may be releasably positioned within the distal tip <NUM> and may be held in place by force of the resilient anchoring members constrained within. After penetration of the sclera with the distal tip. the distal tip <NUM> as well as the inner cylinder attached thereto can be retracted, such as by pulling a proximal feature <NUM> (e.g. thumb ring) attached to the inner cylinder in a proximal direction while maintaining the outer cylinder position with the fingers against stabilizer <NUM>. As the volume of the syringe is reduced, the fluid within the syringe is displaced, which moves the sensor device relative the distal tip during retraction so that the sensor device <NUM> substantially maintains its position and is released from the distal tip <NUM> as shown in <FIG>. Upon release of the sensor device <NUM> from the distal tip <NUM>, the anchoring members <NUM> deploy laterally outward thereby anchoring the sensor device against the sclera. In some embodiments, the sensor device <NUM> may be pushed distally after deployment to facilitate engagement of the anchoring members <NUM> against the sclera and coverage of the anchoring members with the ballooned portion of the conjunctiva. <FIG> depict a syringe <NUM> or injector used in accordance with another implantation method, which is similar to that described above in <FIG> expect the needle or distal tip of die injector does not penetrate through the sclera. Rather, the distal tip is partly inserted into the sclera and the sensor device is advanced, in a similar manner as described above. such that a distal tip of the sensor device continues to advance through the sclera and into the vitreous body.

<FIG> illustrate alternative example sensor devices having differing anchoring configuration and <FIG> illustrate each of the examples after implantation. In some configurations, the sensor device <NUM> may include anchoring members disposed on opposite sides of the sclera, such as shown in <FIG>, which may provide additional anchoring in both proximal and distal directions, as can be understood by referring to their deployed positions as shown in corresponding <FIG>, respectively.

According to the invention, the sensor device <NUM> includes an extraction feature <NUM> that facilitates extraction of the sensor after implantation. The extraction feature <NUM> may include a hole or loop feature that interfaces with an extraction tool <NUM> to allow the sensor device <NUM> to be pulled in a proximal direction and extracted from the eye. The extraction feature <NUM> may include a separate feature attached to the device <NUM> or may be integrally formed with die device itself. In configurations where the anchoring members are defined portions of a substrate or wafer of the sensor device, the extraction <NUM> may be defined in a different portion of the same substrate or wafer. For example, as shown in <FIG>, the anchoring members <NUM> are S-shaped portions of a rigid substrate, such as a silicon wafer, and the extraction feature <NUM> is a hole or opening formed within the same layer. The hole is dimensioned to allow an extraction tool <NUM>, such as a hook-like tool, to be inserted within the hole to allow the implanted sensor device <NUM> to be proximally pulled and extracted from the eye.

<FIG> illustrate additional examples of sensor devices <NUM>. <FIG> illustrates a sensor device <NUM> having two anchoring members <NUM> for engaging an outer surface of the sclera and two additional anchors <NUM>' for engaging an inner surface of the sclera, as well as a proximal extraction feature. In one aspect, the anchoring members <NUM>, <NUM>' are dimensioned so that the anchoring members <NUM> that engage an outer surface of the sclera provide an anchoring force F1 that is greater than an anchoring force F2 provided by the anchoring members <NUM>''' that engage an inner surface of the sclera. This configuration allows for improved anchoring in both distal and proximal directions along the insertion axis, while still allowing for extraction by proximally pulling the extraction feature <NUM> until force F2 is overcome. <FIG> illustrates a sensor device <NUM> having an S-shapcd anchoring member <NUM>, which may be defined so as to provide a spring-like resistance when pushed against the sclera.

<FIG> illustrates a sensor device <NUM> having anchoring members <NUM> and an extraction feature <NUM> at a proximal end of the device <NUM> and a penetrating tip <NUM> formed at the distal tip. In some configurations, the penetrating tip <NUM>. anchoring members <NUM> and extraction feature <NUM> are each formed within a different portion of the same layer, such as a rigid substrate (e.g. a silicon wafer) of the device. Each of the features may be formed using wafer processing techniques such as deep plasma etching. An example of how such a penetrating tip <NUM> can be used is shown in the implantation method shown in <FIG>.

In some configurations, the sensor device <NUM> can be implanted by injecting with a tool or device other than a fluid-filled syringe. In the example method shown in <FIG>, the sclera is partly penetrated by a tool <NUM> leaving only a thin or weakened portion of the sclera. The sensor device is then advanced distally in this region until the penetrating tip <NUM> of the sensor device <NUM> penetrated through the sclera and into the vitreous body, as shown in <FIG>. The sensor device is advanced until the anchoring members <NUM> engage the sclera, as shown in <FIG>. The sensor device <NUM> may be advanced using a pusher tool <NUM> that interfaces with the extraction feature <NUM> such that the extraction feature facilitates implantation and extraction. In this configuration, the extraction/implantation feature <NUM> may be oblong in shape, such as a slot, so as to improve stability and prevent rotation or twisting of the sensor device when being pushed through the sclera with the pusher tool <NUM>. In one aspect, this approach allows for a variety of alternative anchoring configurations since it docs not require that the anchoring members be constrained within a distal tip of a syringe. For example, the anchoring members <NUM> could be relatively fixed in a laterally outward configuration, which may allow for thicker or more rigid anchoring members to be used if desired.

<FIG> illustrate views of an alternative example sensor device <NUM> having a distal penetrating tip <NUM> for advancing through the sclera such as in the implantation method described above and an explantation feature <NUM> at the opposite end. This configuration does not include the anchoring members described above. Such an embodiment may be useful in an application where anchoring is not desired or needed, for example, when used with a shunt that is self-anchoring within the eye.

<FIG> illustrate views of an example sensor device <NUM> formed with a vertically stacked architecture. A wafer or substrate extending through the device is defined to have a penetrating tip <NUM> for advancing through the sclera defined at the distal end of a wafer and an explanation feature <NUM> and anchoring members <NUM> defined in the same wafer at a proximal end of the device <NUM>. In one aspect, the vertically stacked architecture of this device may be the same as that shown in <FIG> of U. Non-Provisional Patent Application Serial No.      (Attorney Docket No. <NUM>-<NUM>) entitled "Hermetically Sealed Implant Sensors with Vertical Stacking Architecture. " <FIG> illustrate various view of an alternative design of a sensor device.

In this alternative design, the distal penetrating tip of the sensor device and the anchoring features arc integral parts of a support structure or boat in which the wafer-stacked sensor device resides and is bonded thereto. While the distal penetrating tip and/or the anchoring features arc described herein as being parts of an interposer layer or a boat support structure, it is appreciated that these components maybe configured in various other ways, including separately formed structures that are bonded to the sensor device after fabrication.

Claim 1:
A system for implanting an intraocular pressure, IOP, sensor in an eye of a patient, the system comprising:
an implantation device (<NUM>) having a distal tip (<NUM>) configured to penetrate through a conjunctiva and a sclera of the eye along a pars planar region and into the vitreous body of the eye; and
a sensor device (<NUM>) disposed in the implantation device, the sensor device having an IOP sensor in a distal portion thereof and one or more anchoring members (<NUM>) in a proximal portion thereof, wherein the IOP sensor comprises a sensing diaphragm (s) disposed in the distal portion, whereby the sensor device is configured such that, when implanted, the sensing diaphragm is configured to be disposed entirely within a vitreous body of the eye, thereby being configured to obtain a direct measurement of the IOP of the vitreous body, wherein the sensor device is disposed within the implantation device, and
device the implantation device is configured to facilitate implantation of the sensor device through the sclera, being configured to to position the IOP sensor within the eye, with the one or more anchoring members being configured to be deployed along the sclera, such that the sensor device is anchored by engagement of the one or more anchoring members against the sclera thereby being configured to maintain the IOP sensor within the vitreous body of the eye,
wherein the sensor device (<NUM>) comprises a proximal extraction feature (<NUM>),
wherein the implantation device (<NUM>) comprises a pusher tool that interfaces with the proximal extraction feature (<NUM>), thereby being configured to facilitate insertion of the sensor device (<NUM>) along an insertion axis extending into the vitreous body, by advancing the pusher tool of the implantation device (<NUM>) interfaced with the proximal extraction feature (<NUM>).