DE102004056756A1 - Device for examination of eyeground, designed as chip accommodated in flat case and attached to sclera - Google Patents

Abstract

The device (1) comprises at least one pressure sensor and a telemetry unit with a connected inductive coil accommodated inside a pressure indicating bio-compatible flat case. The data are transmitted to an exterior telemetric unit (8). The device (1) is inserted into a flat drainage reservoir (12) attached to the outer surface of the sclera (10) connected to a fluid containing chamber (14) at the eye with a drainage cannula (13). The sensor and the telemetry unit are integrated in a chip and the inductive coil attached to its outer surface.

Description

The The invention relates to a device for intraocular pressure measurement with an implantable measuring device, the at least one Pressure sensor and a telemetry device with connected inductive Coil in a pressure transferring and biocompatible serving and with an extracorporeal telemetry interrogator.

Such a device is off DE 199 45 879 A1 known. In the known device, the measured values can be transmitted telemetrically to a receiving device arranged outside the eye.

Out DE 101 06 881 A1 a device for telemetric intraocular pressure measurement is known in which the pressure sensor is arranged on the inner surface of the eye sclera in the region of the pars plana.

Further is from Flick, B.B .; Organ Master, R .; "A portable microsystembases telemetric pressure and temperature measurement unit, IN: IEEE Transaction on Biomedical Engineering, Vol. 47/1, Jan. 2000, pages 12-16 an intracorporeal pressure sensor known which in the intracranial pressure measurement Use finds.

task The invention is an apparatus for intraocular pressure measurement of the type mentioned above, in which the measuring device is implantable in a component of the eye.

These The object is achieved by the characterizing features of claim 1 solved.

The under claims contain advantageous developments of the invention.

In the invention, the intracorporeal measuring device is arranged in a flat envelope. The enclosure with the measuring device arranged therein is arranged in a drainage reservoir, which is connected via a drainage cannula with a space containing eye chamber water in the eye, in particular the anterior chamber, during the implantation. Such a drainage reservoir, which can be arranged between the outer surface of the ocular sclera and the Tenon capsule during implantation, is made of US 5,178,604 known. About the cannula excess aqueous humor is supplied from the inside of the eye, especially the anterior chamber of the reservoir.

The reservoir can be a thin, fibrous capsule that forms around a support to which the intracorporeal measuring device is attached after implantation between the tenon capsule and the outer surface of the sclera in the form of a drainage bleb in the tenon space ( US 5,178,604 ). However, the reservoir can also be formed as an artificial reservoir in the form of a flat, adapted to the Tenonraum hollow body with a thin shell. Optionally, the artificial reservoir may comprise a valve through which aqueous humor can escape. In the interior of the reservoir, the measuring device is preferably fastened to a carrier on which the drainage cannula, which consists for example of a silicone tube, is fixed.

The Intracorporeal measuring device includes at least one pressure sensor and the electronic telemetry device, which is in a chip can be integrated. Preferably, the electronic components of the telemetry device With the inductive coil by bonding directly electrically contacted. The at least one pressure sensor is located on one side and the inductive coil on the other side of the flat chip body. It can however, the pressure sensor and the inductive coil are also at the same surface side of the chip body be provided. When implanting in the sclera is at least a pressure sensor preferably directed towards the inside of the eye Side of the chip body and the coil on the outside directed side of the chip body.

Of the Intraocular pressure, which is called the pressure difference between the absolute Defines pressure inside the eye and the air pressure surrounding the eye is, and in particular, an elevated one Intraocular pressure leads to a pressure change also in the reservoir, which can be detected by the pressure sensor. In an advantageous manner Way, this pressure is over a relatively large volume and pressure transmitting Medium, which is a liquid, a gel or oil may be transmitted to the at least one pressure sensor. The pressure transferring Medium can do this in a z. B. by gluing, vulcanization or welding closed and deformable film, which together with the pressure transferring Medium the serving forms, be arranged. The serving can also be an enveloping body biocompatible material, e.g. As silicone.

The chip is characterized by a low volume and can be sized in height, in particular smaller than 0.5 mm. The chip area can be a few mm ² . The coil can also with low height, for example, about 20 microns as Pla narspule or also with a smaller height dimension than preferably deformable wound coil can be formed. The coil can be produced by microsystem technology, for example by microgalvanization, in particular photolithographically. The total height of the measuring unit, including the sheath, may be sized 0.7 mm or smaller and with a corresponding incision in the sclera, e.g. B. Sclera pocket can be arranged.

With an implant, which the chip and the inductive Coil has, the measured value, the energy transfer and telemetric data transmission, especially in digital form. In the chip are preferably the pressure transducer, optionally a temperature measuring device, the analog / digital converter and the telemetry / transponder electronics accommodated. The pressure measurement is preferably carried out capacitively. For this purpose can the pressure-sensitive surface are formed by one or more membranes, respectively forms a capacitor assignment in the capacitive pressure measurement. It can also several pressure-sensitive surfaces, in particular membranes be provided. It can be achieved with such a measuring device a high transponder range of several cm. At a transponder frequency between 10 and 15 MHz, for example 13.56 MHz becomes a range of about 5 cm.

With biocompatible serving is a flexible adaptation of the measuring device to the outer surface of Sclera, in particular to the tenon space at the implantation site. The coil can be outside dimensions between about 5.0 mm and 8.0 mm. The coil can be circular, square, be formed rectangular or elliptical. The coil is together with the chip in the pressure transferring Medium of serving embedded. In the invention, an implantable measuring device created in the geometry of the anatomical conditions adjusted at the implantation site. For the implantable measuring device can be a single chip with small dimensions and therefore smaller Pressure receiving surface be used. Due to the pressure transferring medium into which the chip is embedded, is at the site or implantation site an enlarged pressure receiving surface of Measuring device reached. Preferably, several are on the chip for the pressure measurement For example, four pressure receiving surfaces, in particular membranes for the provided capacitive pressure measurement.

At the Chip can Furthermore, in particular passivated pressure measuring points should be provided, which applied with a fixed predetermined (standardized) pressure are. For the detection of intraocular pressure will be the difference between the pressure transmitting Medium mediated pressure and standardized pressure used. This achieves a compensation of drifts and others influences on the pressure transducer. Because no electrical connection lines are provided between the coil and the chip, but the chip directly connected to the coil, for example by flip-chip bonding is, can low external dimensions adapted to the measuring or implantation site the implantable measuring device can be achieved. Due to the One-chip solution is the susceptibility the measuring device compared to systems with several modules low.

The Measuring device can transmit after its wrapping with the pressure Medium be pre-calibrated. The final calibration is done for example, using a conventional tonometer after Implantation. By change of intraocular pressure, the mechanical stress states become within the sclera changed. This changes also on the pressure sensors, in particular their measuring membranes applied pressure. The determination of the transfer function of Intraocular pressure for pressure on the diaphragm may be patient specific by sensor measurement of at least two different intraocular pressure values by means of conventional Tonnometers can be determined in the classical way. From the calibration function the not yet implanted measuring device (pre-calibration) and the at least two tonometrically determined on the patient measured values determines the patient-specific characteristic. The thereby determined Characteristic can be integrated in the integrated telemetry electronics or stored in the extracorporeal retrieval and evaluation device.

Everyone Chip can have a specific identifier at every telemetric Measurement queried and the processing of the measurement data processing device is assigned. In this way, multiple implantable Measuring devices, for example, up to several hundred measuring devices be processed with an evaluation. The detection will performed with a telemetric interrogator. at The calibration of the measuring device is determined a certain characteristic. This characteristic is preferably in the query or evaluation stored associated with the specific identifier of the chip. hereby recognizes the interrogation or evaluation device in the telemetric Measurement of the respective measuring device and taken into account in the evaluation the associated Curve.

The query and the evaluation device and a recording device connected thereto may be placed in a unit which is preferably designed as a handheld device. The Interrogator also includes the extracorporeal induction coil which is connected to the extracorporeal telemetry device. The interrogator can be connected via a cable to the evaluation device. However, it is also possible to transmit the measurement data from the interrogation device to the evaluation device by radio transmission. It is also possible to fix the interrogator or at least the associated extracorporeal coil in the eye or tail area with the aid of a fixing device, for example on a spectacle frame or with the aid of a patch on the scalp of the patient. The extracorporeal coil may be connected to the interrogation and evaluation device via a cable or other suitable electrical connection.

at The invention is a permanent one Measurement of intraocular pressure possible. It can especially in glaucoma patients all pressure fluctuations that occur throughout the day can, be recorded. This achieves a more accurate detection of the Disease process.

Based the figures is based on an embodiment the invention even closer explained.

It shows

1 an eye detail with an implanted in Tenonraum of the eye measuring device and extracorporeal interrogator in a schematic representation;

2 a perspective view of a first embodiment of the intracorporeal measuring device;

3 a schematic side view of a second embodiment of the intracorporeal measuring device; and

4 a schematic side view of a third embodiment of the intracorporeal measuring device.

The in the 2 to 4 illustrated implantable measuring devices 1 include a single hybrid chip 7 and an inductive coil 4 on the outside of the chip 7 is arranged. If the transmission properties are sufficient, the coil can also be integrated in the chip body. The chip 7 includes a pressure sensor 2 with one or more pressure receiving surfaces, which may be formed as membranes. The membranes are part of, in particular capacitor assignments of a capacitive pressure sensor. The pressure-receiving surfaces measure the pressure, which results from the respective stress state of the sclera and depends on the absolute pressure inside the eye. From this, the intraocular pressure, which is the pressure difference between the absolute pressure in the eye and the air pressure surrounding the eye, z. B. by means of the previously detected characteristic (calibration curve) can be determined. Furthermore, in the chip 7 an analog / digital converter and a telemetry device provided with a telemetry / transponder electronics. The electronics are connected via an electrical contact 3 , z. B. flip-chip bonding directly to the inductive coil 4 contacted.

The inductive coil 4 is on one of the two surfaces of the chip 7 arranged. In the embodiment of 2 the inductive coil is on the same surface side of the chip 7 like the pressure sensor 2 , In the embodiment of 3 is the pressure sensor 2 on the one surface side (underside) of the chip 7 and the inductive coil 4 is located on the other surface side (top side) of the chip 7 , In the embodiments of the 2 and 3 is the inductive coil 7 designed as a planar coil. In the embodiment of 4 is the inductive coil 4 on the periphery of the chip 7 arranged. For this purpose, the coil may be formed as a thin wire coil. However, it is also possible in the embodiment of 4 a planar coil, for example, to use a multilayer planar coil. Also in the embodiments of the 2 and 3 Multi-layer planar coils or thin wire coils can be used.

In the implanted state is preferably the surface with the pressure sensor 2 into the inside of the eye and the surface with the inductive coil 4 directed to the outside. This can be with the in 3 realize embodiment shown. Like from the 2 to 4 can be seen are the chip 7 and the coil 4 from a serving 5 which is a flexible closed shell 6 may be surrounded. Inside the case 6 there is a pressure transmitting medium 11 , in particular a gel or a biocompatible liquid, for example silicone-based oil. The chip 2 and the adjacent coil region become pressure-tight by the pressure-transmitting medium 11 envelops or are in pressure-transmitting medium 11 embedded. The case 6 , which may be formed as a film, can be closed by welding, gluing or vulcanization. The serving 5 can also us from a biocompatible envelope, z. As silicone, which is also the pressure-transmitting medium 11 forms exist. For the shell 6 For example, a polyurethane film or silicone film is suitable.

The case 6 surrounds the pressure transmitting medium 11 preferably de-energized, so that an undisturbed transfer of the intraocular pressure to be measured on the pressure-sensitive sensor surfaces of the chip 7 integrated pressure sensor 2 is reached. The pre-calibration of the measuring device 1 done after the serving 5 is closed, ie after completion of the implantable measuring device 1 , The final calibration, as already explained, is done after implantation.

The turns of the coil 4 are preferably prepared by microsystem technology, in particular photolithographic methods. The coil turns can be provided as planar coil turns next to one another and / or one above the other on the chip body. The coil may for example have a height of 20 microns. In this way, a measuring device can be 1 with a total height or total thickness, including the wrapping, of 0.7 mm and manufacture. The length can be from 5.0 mm to 8.0 mm. The width can be from 1.0 mm to 2.0 mm.

The measuring device 1 which attaches to the outer surface of the ocular sclera 10 Attached carrier is attached between the tenon capsule 15 and the outer surface of the eye sclera 10 implanted. On the support is a drainage cannula 13 , For example, in the form of a silicone tube attached. The cannula is placed between the cornea and the iris of the eye in the anterior chamber 14 placed. The reservoir 12 forms as if US 5,178,604 is known as a closed fibrous capsule around the carrier and the measuring device 1 out. About the drainage cannula 13 Excess ocular water comes out of the anterior chamber 14 into the interior of the reservoir 12 , In this way, the absolute intraocular pressure, which is also inside the reservoir 12 builds up, with the measuring device 1 measured.

It is also possible the reservoir 12 as a thin, biocompatible shell, which optionally has a valve not shown in detail, form and inside the reservoir, the measuring device 1 to arrange.

To carry out the measurement extrakorporal an interrogator 8th near the implanted measuring device 1 brought. For this purpose, the interrogation device in the eye or temporal region of the patient by means of a fixing device 9 , what a 1 is shown only schematically attached to a pair of glasses or by means of a patch on the head of the patient. The polling device 8th has an inductive coil for telemetric energy transfer to the inductive coil 4 the measuring device 1 and for receiving the telemetrically transmitted measurement data of the implanted measuring device 1 , At least the inductive coil of the interrogator 8th can be attached to the patient's head in transponder range. This allows measurement data to be constantly polled. The polling device 8th can be designed as a handheld device and via a cable 15 be connected to an evaluation device with display device. However, it is also possible to integrate the evaluation device and a display device in the handset. Furthermore, the interrogator 8th transmit the measurement data to an evaluation device via radio.

The calibration of in 1 shown measuring arrangement can after implanting the measuring device 1 in the eye sclera 10 respectively. The calibration curve or characteristic curve is created using a conventional tonometer, as already explained.

1

measuring device

2

pressure sensor

3

electrical contact

4

inductive Kitchen sink

5

wrapping

6

closed shell

7

chip

8th

interrogator

9

fixing

10

Augensklera

11

Pressure transmitting medium

12

drainage reservoir

13

drainage cannula

14

Anterior chamber

15

Tenon's capsule

Claims (9)

Device for intraocular pressure measurement with an implantable measuring device having at least one pressure sensor and a telemetry device with connected inductive coil in a pressure-transmitting and biocompatible sheath, and an extracorporeal telemetric interrogator, characterized in that in a flat sheath ( 5 ) arranged measuring device ( 1 ) in a flat and on the outer surface of the eye sclera attachable drainage reservoir ( 12 ), which via a drainage cannula ( 13 ) is connectable with an eye chamber water containing space in the eye, is arranged. Apparatus according to claim 1, characterized in that the pressure sensor ( 2 ) and the telemetry device ( 3 ) in a chip ( 7 ) and the inductive coil ( 4 ) is disposed at or near the outside of the chip body. Device according to claim 1 or 2, characterized in that the inductive coil ( 4 ) on the surface side of the chip body ( 7 ), at which the at least one pressure sensor ( 2 ), or on the opposite surface side of the chip body ( 7 ) is arranged. Device according to one of claims 1 to 3, characterized in that the inductive coil ( 4 ) at the periphery of the chip body ( 7 ) is arranged. Device according to one of claims 1 to 4, characterized in that the inductive coil ( 4 ) is designed as a planar coil or as a thin wire coil. Device according to one of claims 1 to 4, characterized in that the envelope ( 5 ) a closed envelope ( 6 ), in which at least the pressure sensor ( 2 ) in a pressure-transmitting medium ( 11 ) with respect to the pressure sensor ( 2 ) is arranged enlarged pressure transfer surface. Device according to one of claims 1 to 6, characterized in that the pressure-transmitting medium ( 11 ) is a gel. Device according to one of claims 1 to 5, characterized in that the envelope ( 5 ) is formed by an enveloping body forming the pressure-transmitting medium. Device according to one of claims 1 to 8, characterized in that the extracorporeal interrogator ( 8th ) can be placed on a fixing device which can be placed in the vicinity of the eyes or the patient ( 9 ) is arranged or provided in a hand-held device.