Device for optically representing intraocular pressure, and a method for same
A device for optically representing intraocular pressure, having an arrangement which is implanted into the eye with a membrane that curves outwards when the intraocular pressure changes, and a contact surface, these altering the polarization for a spectral range of incident and reflected light in the region of their contact with one another, as well as a read-out arrangement that optically reproduces a planar image of the light which is reflected by the photonic crystal and whose polarization has been altered, and that comprises a polarization filter for the irradiated light and the light reflected by the photonic crystal. Also, a method for measuring intraocular pressure.
1. An apparatus for optical representation of intraocular pressure, the apparatus comprising:
an intraocular pressure sensor mounted within an intraocular lens (IOL), the intraocular lens adapted to be implanted in an eye, wherein the intraocular pressure sensor includes a reference pressure chamber having:
a membrane which bulges with changing intraocular pressure when implanted in the eye, the membrane being optically transparent, and
a contact surface comprising a photonic crystal having a periodically nanostructured surface situated within the reference pressure chamber, wherein the membrane is deflectable out onto the periodically nanostructured surface of the photonic crystal when the membrane bulges with changing intraocular pressure, whereby in the area of contact between the membrane and contact surface a change in a spectral range of incident light and reflected light is caused, and
an external readout device adapted to be used with the intraocular pressure sensor, the readout device including a circular polarization filter in the path of incident light and a circular polarization filter in the path of the light reflected by the photonic crystal,
wherein when the membrane contacts the photonic crystal, it causes the light which is reflected by the photonic crystal to be altered in polarization,
wherein the readout device optically reproduces a planar image of the light which is reflected by the photonic crystal and whose polarization has been altered, and
wherein the circular polarization filter in the path of incident light and the circular polarization filter in the path of the light reflected by the photonic crystal are crossed by 90°, to represent the area of the contact surface as a difference image.
2. The apparatus according to claim 1 , wherein a camera is provided as part of the readout device, whereby a storable image is produced.
3. The apparatus according to claim 2 , wherein a camera image is produced and the camera image is then processed with computer means using a known reference value contained in the image for the determination of a quantified value of the intraocular pressure from the size of the detected contact area.