Implant for determining intraocular pressure

Abstract

An implant for determining intraocular pressure includes at least one electrical pressure sensor for measuring the intraocular pressure, at least one microchip that is connected to the pressure sensor, and at least one antenna that is connected to the microchip, the microchip generating digitally encoded data from the electrical signals of the pressure sensor, which data can be transmitted by an antenna, using electromagnetic waves, to a receiver located outside the eye, and components being accommodated in a small housing, the outer dimensions of which are limited such that the implant can be positioned between the sclera and the choroid of the eye, is improved in that the pressure sensor is accommodated on an outer housing side of the implant, which outer housing side is brought into contact with the choroid in the eye.

1 . Implant for determining intraocular pressure, comprising at least one electrical pressure sensor ( 6 ) for measuring the intraocular pressure, at least one microchip ( 7 ) that is connected to the pressure sensor ( 6 ), and at least one antenna ( 8 ) that is connected to the microchip ( 7 ), the microchip ( 7 ) generating digitally encoded data from the electrical signals of the pressure sensor ( 6 ), which data can be transmitted by the antenna ( 8 ), using electromagnetic waves, to a receiver located outside the eye ( 2 ), and said components being accommodated in a small housing ( 11 ), the outer dimensions ( 12 ,  13 ,  14 ) of which are limited such that the implant ( 1 ) can be positioned between the sclera ( 3 ) and the choroid ( 4 ) of the eye ( 2 ), characterised in that the pressure sensor ( 6 ) is accommodated on an outer housing side ( 16 ) of the implant ( 1 ), which outer housing side is brought into contact with the choroid ( 4 ) in the eye ( 2 ). 
     
     
         2 . Implant according to  claim 1 , characterised in that the outer housing side ( 16 ) provided with the pressure sensor ( 6 ) comprises a flexible membrane ( 18 ) in the region of the pressure sensor ( 6 ) as a protective layer against ingress of liquid, the intraocular pressure acting on the pressure sensor ( 6 ) via the choroid ( 4 ) and the membrane ( 18 ). 
     
     
         3 . Implant according to  claim 1 , characterised in that the housing ( 11 ) thereof is flat and elongate, preferably in the shape of an ellipsoid or cuboid having rounded corners and edges. 
     
     
         4 . Implant according to  claim 3 , characterised in that the length ( 12 ) of the housing ( 11 ) is less than 7 mm, its width ( 13 ) is less than 3.5 mm and its thickness ( 14 ) is less than 2 mm. 
     
     
         5 . Implant according to  claim 1 , characterised in that the housing ( 11 ) is moulded from plastics material. 
     
     
         6 . Implant according to  claim 1 , characterised in that the housing ( 11 ) is provided with suture loops on the outside for fixing the implant ( 1 ) in the eye ( 2 ). 
     
     
         7 . Implant according to  claim 1 , characterised in that the housing ( 11 ) comprises nubs ( 17 ) on the outer housing side ( 15 ) facing the sclera ( 3 ), which nubs are arranged in the manner of the corners of a triangle. 
     
     
         8 . Implant according to  claim 1 , characterised in that the housing ( 11 ) is concave on the outer housing side ( 16 ) thereof facing the choroid ( 4 ). 
     
     
         9 . Implant according to  claim 1 , characterised in that it is provided with an electronic temperature sensor ( 19 ) that is connected to the microchip ( 7 ) and is intended for measuring the temperature of the eye, and in that the microchip ( 7 ) generates data from the electrical signals of the temperature sensor ( 19 ), which data can be transmitted by the antenna ( 8 ), using electromagnetic waves, to the receiver located outside the eye ( 2 ). 
     
     
         10 . Implant according to  claim 1 , characterised in that the antenna ( 8 ) consists of an electrical coil that surrounds the microchip ( 7 ) provided with the pressure sensor ( 6 ). 
     
     
         11 . Implant according to  claim 1 , characterised in that it is coated with a pharmacologically active substance, e.g. heparin or mytocin C, in order to prevent reactions of the eye such as inflammation, coagulation, tissue formation or encapsulation that would be detrimental either to the eye or to the pressure measurement. 
     
     
         12 . Implant according to  claim 1 , characterised in that it comprises an energy store that is charged from the outside by means of transformer coupling or energy harvesting (saccades). 
     
     
         13 . Implant according to  claim 1 , characterised in that it is provided with at least one solar cell for charging the internal energy store. 
     
     
         14 . Implant according to  claim 1 , characterised in that, as an active RFID tag, it is provided with a data store in order to carry out measurements autonomously and to save the measurement data in the data store until said data are retrieved, by means of a radio link, by a reader located outside the eye ( 2 ). 
     
     
         15 . Pressure measurement arrangement comprising an implant ( 1 ) according to  claim 1  and a reader arranged outside the eye ( 2 ) for receiving measurement data that are transmitted by the implant ( 1 ) via a radio link to a receiver of the reader, characterised in that the reader is provided with a timer, an air pressure sensor and a data store, and in that it provides the air pressure data of the air pressure sensor with a time stamp and saves said data in the data store in order to temporally assign the saved air pressure data to the intraocular pressure measurement data delivered by the implant ( 1 ) and to correct said air pressure data, with respect to air pressure influences, to the intraocular pressure.