WO2024213314A1

WO2024213314A1 - Head-wearable device for detecting metabolic states in the eye

Info

Publication number: WO2024213314A1
Application number: PCT/EP2024/055829
Authority: WO
Inventors: Johannes Haase
Original assignee: Ams Osram AG
Current assignee: Ams Osram AG
Priority date: 2023-04-14
Filing date: 2024-03-06
Publication date: 2024-10-17
Anticipated expiration: 2025-10-14
Also published as: KR20250164218A; CN120957650A; DE112024001247T5

Abstract

A device for detecting metabolic states in the eye, comprises a frame (10) for wearing the device on a head of a human or animal body, and a light emitting and evaluation apparatus (20). The frame (10) has a support (11) for supporting the light emitting and evaluation apparatus (20). The light emitting and evaluation apparatus (20) is configured for emitting light for excitation of molecules to be detected in the tear film (30) of the eye (2). The light emitting and evaluation apparatus (20) is configured to generate an output signal in response to a detection of an interference of a portion of light reflected back from the eye (2) to the light emitting and evaluation apparatus (20).

Description

HEAD-WEARABLE DEVICE FOR DETECTING METABOLIC STATES IN THE EYE

Technical Field

The disclosure relates to a head-wearable device for detecting metabolic states in the eye by monitoring the tear liquid of the eye . The disclosure further relates to a method for detecting metabolic states in the eye by monitoring the tear liquid of the eye .

Background

For medical diagnostics , a patient ' s blood is usually examined, as biomarkers are found in the blood that provide information about the state of health of the patient ' s organism . The examination of the blood is laborious . The blood collection as well as the blood examination can only be carried out by speciali zed personnel . Furthermore , a blood test can only determine the condition of a body at a certain point in time , namely at the time the blood is taken . Consequently, the blood collection must be repeated at certain intervals , which is unpleasant for the patient concerned .

A large proportion of the biomarkers found in the blood can also be found in other body fluids . Such biomarkers are also present , at least to a large extent , for example , in the tear liquid in the eye or the tear film of the eye . These biomarkers contained in the tear liquid can be , for example , sugar level , ketones or more complex molecules . The detection of sugar molecules in the tear liquid/ film allows conclusions to be drawn about the sugar content and thus the sugar level in the blood . The sugar level can then be used, for example , to assess the function of the pancreas . The ketone level allows the sugar burning or fat burning state to be indicated and thus conclusions to be drawn about liver function . The tear liquid/ film thus contains information on the metabolic state of an organism .

Unlike the taking of a blood sample , the collection of tear fluid from the eye is di f ficult to almost impossible , as larger quantities of tear fluid would have to be collected for examination purposes .

It would be welcome in the art to provide a device for detecting metabolic states in the eye which allows a non- invasive and continuous monitoring of biomarkers in the tear liquid of the eye .

Summary

An embodiment of a device for detecting metabolic states in the eye by detecting biomarkers , for example speci fic molecules in the tear film of the eye , wherein the device allows a continuous monitoring of the metabolic states of a body is speci fied in claim 1 .

The proposed device for detecting metabolic states in the eye comprises a frame for wearing the device on the head of a human or animal body . The device further comprises a light emitting and evaluation apparatus . The light emitting and evaluation apparatus is configured for emitting light for excitation of molecules to be detected in the tear film of the eye . The light emitting and evaluation apparatus is further configured to generate an output signal in response to a detection of an interference of a portion of light reflected back from the eye to the light emitting and evaluation apparatus . The frame has a support for supporting the light emitting and evaluation apparatus .

When the wavelength of the emitted light is speci fic to the wavelength speci fic absorption of the molecules to be detected, only the speci fic molecules of interest are excited in the tear liquid . By absorbing the light irradiated by the light emitting and evaluation apparatus towards the eye , the molecules to be detected in the tear film of the eye heat up, which causes the tear liquid and especially the outer layer of the tear liquid to expand . The strength of the expansion of the tear liquid or the outer layer of the tear film is a measure for the concentration of the light-absorbing molecules in the tear liquid .

The expansion of the tear liquid or the outer layer of the tear film can be measured by the light emitting and evaluation apparatus using a sel f-mixing interferometry detection scheme . The light reflected back at the outer layer of the tear film interferes with the emitted light inside of the light emitting and evaluation apparatus . The light emitting and evaluation apparatus provides the ( SMI ) output signal in response to the detected interference of both of the emitted and reflected light inside of the light emitting and evaluation apparatus .

The proposed device for detecting metabolic states in the eye thus allows , by a non-invasive method, speci fic molecules to be detected in the tear fluid/ liquid and in particular their concentration to be measured . The molecules to be detected may be metabolites and their concentration is an indication of the metabolic state of a body . The proposed device for detecting metabolic states in the eye thus enables conclusions to be drawn about the state of health of a body .

The light emitting and evaluation apparatus can be configured to allow the excitation of molecules to be tuned to the wavelength speci fic absorption of the molecules of interest . For this purpose , according to a possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus is configured to emit light with a wavelength being tuned to the wavelength-speci fic absorption of the molecules to be detected in the tear film of the eye . The light emitting and evaluation apparatus can thus be adj usted so that the wavelength of the emitted light corresponds to the absorption spectrum of the molecules to be stimulated and detected .

According to a possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus is configured to emit light in the infrared ( IR) range or the near-infrared (NIR) range or the mid-infrared (MIR) range . That means that an IR- , NIR- or MIR-light source may be used to excite the speci fic molecules in the tear liquid .

According to a possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus is configured to be controlled to modulate the emitted light in amplitude . By modulating the emitted light in amplitude , the local expansion of the tear liquid due to molecular absorption will be modulated as well . The modulated expansion of the tear liquid leads to a surface vibration of the outermost layer of the tear film of the eye .

According to a possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus is configured to provide the output signal with a level representing the strength of surface vibrations of the lipid layer of the tear film of the eye . The lipid layer is the outermost layer of the tear film . The surface vibrations of the lipid layer are caused by the excitation and absorption of the emitted light by the molecules to be detected in the tear film of the eye .

In order to monitor the oscillation of the lipid layer, the light emitting and evaluation apparatus uses an SMI-based surface vibration detection scheme . The principle is basically equivalent to an SMI-based optical microphone , however, without the use of an extra microphone . The proposed approach is thus much more direct and therefore more sensitive than the use of photoacoustic spectroscopy . A high/ low concentration of absorbing molecules in an aqueous layer of the tear film underneath the lipid layer of the tear film will lead to a high/ low amplitude of the detected surface vibration of the lipid layer, and can therefore be used to analyze the concentration of the metabolite .

According to a possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus is configured to be controlled to periodically change the wavelength of the emitted light . The light emitting and evaluation apparatus thus allows the emitted light to be swept in wavelength for photo vibrational detection . The excitation of the molecule to be detected in the tear film is modulated with the sweep frequency, especially when the range of the wavelength to be swept is selected so that the molecular absorption is j ust at the edge of the wavelength sweep range/ sweep window . As a result , the molecule excitation in the tear film is modulated with the wavelength sweep frequency which leads to the surface vibration in the lipid layer of the tear liquid .

According to a possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus may comprise a first light emitting device and a second light emitting device . The first light emitting device is configured for emitting light towards the eye and to receive reflected light being a portion of the emitted light that is reflected back to the first light emitting device . The light emitting an evaluation apparatus is configured to evaluate an interference of the emitted light and the reflected light occurring inside the light emitting device by sel f-mixing interferometry . The second light emitting device is configured for emitting the light for the excitation of the molecules to be detected in the tear film of the eye .

According to this embodiment , the light emitting and evaluation apparatus comprises a separate ( second) light emitting device for the excitation of the molecules of interest to be detected and monitored in the tear liquid, and a di f ferent and separate ( first ) light emitting device for emitting the portion of the light which is reflected back from the eye , particularly from the lipid layer of the tear film of the eye , to the first light emitting device to provide the interference of light signals to be evaluated by the light emitting and evaluation apparatus via sel f-mixing interferometry . The light emitting and evaluation apparatus may comprise a plurality of second light emitting devices , for example one of the second light emitting devices provided for each di f ferent species of molecules to be detected . The excitation needs to happen at di f ferent frequencies and in the SMI signal it will be discriminated by the Fourier trans form .

According to this embodiment using separate light emitting devices for excitation and reflection, the second light emitting device may be configured as a non-coherent light source , for example a non-coherent IR, NIR, or MIR light source . The first light emitting device may be configured as a coherent light source , i . e . for example a laser device .

The light emitted by the first light emitting device/ laser device is reflected back at the lipid layer of the tear film of the eye into the cavity of the laser device to be evaluated by the light emitting and evaluation apparatus . In particular, an interference of the light emitted by the first light emitting device/ laser light source and the portion of the light reflected back to the first light emitting device , i . e . reflected in the cavity of the laser device , is then evaluated by sel f-mixing interferometry .

According to another possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus comprises a light emitting device being configured to emit the light for the excitation of the molecules and to receive reflected light being the portion of the emitted light that is not absorbed and rather reflected back to the light emitting device . The light emitting and evaluation apparatus is configured to evaluate an interference of the emitted light and the reflected light occurring inside the light emitting device by sel f-mixing interferometry .

According to this proposed approach of the device for detecting metabolic states in the eye , the light emitting device of the light emitting and evaluation apparatus is used to emit the light for excitation of the molecules to be detected in the tear liquid and for providing the interference of the emitted light and the portion of the light reflected from the lipid layer of the tear film back to the light emitting device . In this case , the light emitting device may be configured to emit coherent light . In particular, the light emitting device is configured as a laser device , and the light reflected at the lipid layer of the tear liquid is coupled into the cavity of the laser device so that the back-ref lected/non-absorbed light is interfering with the coherent emitted light of the light emitting device leading to the ( SMI ) output signal .

The ( SMI ) output signal allows the distance between the light emitting device of the light emitting and evaluation apparatus and the lipid layer of the tear film to be measured, and therefore also the surface vibrations of the lipid layer caused by the excitation of the molecules in the aqueous layer of the tear film . The proposed merge of an excitation and detection light source in a single device leads to less power consumption in comparison with the abovedescribed embodiment using a separate light emitting device for the excitation of the molecules in the tear liquid and another separate light emitting device for the emission of light to be reflected back at the lipid layer of the tear film . According to a possible embodiment of the device for detecting metabolic states in the eye , the light emitting and evaluation apparatus is arranged at the support of the frame of the device in a way so that the emitted light is directed towards the conj unctiva or the iris of the eye . That means that the support of the frame is oriented so that the light emitted by the light emitting and evaluation apparatus does not enter the pupil of the eye . Furthermore , according to the proposed photo vibrational detection scheme , high intensities of the light emitted towards the eye are not required to excite the molecules in the tear liquid . In conclusion, damage to the eye is not be expected by the proposed device for detecting metabolic states in the eye .

According to a possible embodiment , the device for detecting metabolic states in the eye can be configured as eye glasses . The support for supporting the light emitting and evaluation apparatus may be disposed in the frame of the eye glasses which also includes the lenses of the eye glasses . The eye glasses may further comprise a holding section for holding the device on the head of a human or animal body .

The eye glasses may be configured as prescription glasses , AR ( augmented reality) , VR (virtual reality) , or XR ( extended reality) glasses . However, it has to be noted that any other glasses or head-wearable devices which allow emitters and detectors to be mounted in the frame of the glasses to point towards the eye may be used as the device for detecting metabolic states in the eye . The integration of the proposed photo-vibrational detection scheme for detecting metabolites in the eye into everyday worn glasses allows for continuous non-invasive monitoring of metabolic states in the eye . A non-invasive method for detecting metabolic states in the eye is speci fied in claim 12 .

According to the proposed method, the eye of a human or animal is irradiated by emitting light towards the eye for excitation of molecules to be detected in the tear film of the eye . A portion of light reflected back from the tear film of the eye is evaluated by sel f-mixing interferometry . An output signal is provided in response to the evaluation of the portion of the light reflected back from the tear film of the eye by sel f-mixing interferometry .

An interference of light emitted towards the eye for excitation of the molecules to be detected in the tear film of the eye with the portion of light reflected back from the tear film of the eye is evaluated by sel f-mixing interferometry .

According to the proposed method, the light emitted towards the eye may be generated with a wavelength tuned to the wavelength-speci fic absorption of the molecule to be detected in the tear film of the eye so that only particular, selected molecules of interest can be monitored and analysed .

According to another embodiment of the method, the output signal is provided with a level representing the strength of surface vibrations of a lipid layer of the tear film . The surface vibrations of the lipid layer are caused by the excitation and absorption of the emitted light by the molecule to be detected in an aqueous layer of the tear film . The strength of the vibration is a measure of the number and thus the concentration of the excited molecules in the tear liquid .

Additional features and advantages of the device for detecting metabolic states in the eye are set forth in the detailed description that follows . It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework for understanding the nature and character of the claims .

Brief Description of the Drawings

The accompanying drawings are included to provide further understanding, and are incorporated in, and constitute a part of , the speci fication . As such, the disclosure will be more fully understood from the following detailed description, taken in conj unction with the accompanying figures in which :

Figure 1 illustrates a cross-section of the eye with di f ferent fluid layers of the tear liquid and their essential components ;

Figure 2 illustrates the general principle of the proposed device for detecting metabolic states in the eye by using a photo-vibrational detection scheme and a sel f-mixing interferometry technology;

Figure 3 shows an embodiment of a light emitting and evaluation apparatus of a device for detecting metabolic states in the eye comprising separated light emitting devices for exciting of molecules to be detected in a tear film of the eye and for detecting metabolites in the tear film of the eye by photo-vibrational detection by sel f-mixing interferometry;

Figure 4 shows a second embodiment of a light emitting and evaluation apparatus of a device for detecting metabolic states in the eye with a single light emitting device for exciting of molecules to be detected in the tear film of the eye and for detecting metabolites in the tear film of the eye by photo-vibrational detection by sel f-mixing interferometry; and

Figure 5 shows an embodiment of a device for non-invasive continuous detection and monitoring of metabolic states in the eye .

Detailed Description

Figure 1 shows a cross-sectional view of an eye 2 with a tear film/ liquid 30 covering the conj unctiva 40 , the iris 50 and the pupil 60 of the eye . The tear liquid 30 includes , among other things , a lipid layer 31 covering an essentially aqueous layer 32 . The lipid layer 31 is the uppermost layer of the tear film and prevents the underlying layers of the tear film from evaporating . The di f ferent fluid layers of the tear liquid/ film 30 with their components and an example of a molecular structure are shown in the right image area of Figure 1 .

In particular, the aqueous layer 32 contains components that are largely also present in the blood and are considered as biomarkers with which conclusions can be drawn about the state of health of an organism . The biomarkers can be , for example , sugar level , ketones or more complex components and molecules . The ketone level is , for example , a key indicator for the metabolic state of an organism and can be used, for example , to analyze the relationship between fat and carb burning . The tear liquid thus contains information on the metabolic state of an organism .

In the following, a device is described that makes it possible to analyze the tear film/ liquid 30 with regard to the presence of certain molecules . In particular, the device allows metabolic products contained in the tear liquid to be detected, and thus to draw conclusions about the metabolic state of a body .

Referring to Figure 2 , the device for detecting metabolic states in the eye comprises a light emitting and evaluation apparatus 20 . The light emitting and evaluation apparatus 20 is configured for emitting light for the excitation of molecules to be detected in a tear liquid/ film 30 of an eye 2 of a human or animal body . Depending on the wavelength of the emitted light , certain molecules can be excited in the tear liquid . The molecules excited by the emitted light absorb the light and heat up .

As a result of this heating, the tear liquid expands and thus the outer layer/ lipid layer 31 of the tear film also expands . The strength of the expansion of the tear liquid essentially depends on the concentration of the excited molecules in the aqueous layer 32 of the tear liquid/ film 30 .

Part of the light emitted by the light emitting and evaluation apparatus 20 that is not absorbed by the molecules in the tear liquid is reflected by the outer layer/ lipid layer 31 of the tear film in the direction of the light emitting and evaluation apparatus 20 . The light emitting and evaluation apparatus 20 is configured to provide an SMI output signal in response to a detection of an interference of a portion of light reflected back from the eye 2 to the light emitting and evaluation apparatus 20 .

In particular, the back reflected (non-absorbed) light interferes with the emitted light leading to an SMI output signal provided by the light emitting and evaluation apparatus 20 . The SMI output signal allows the distance between the light emitting and evaluation apparatus 20 and the outer layer 31 of the tear film to be measured, and therefore also allows the surface expansion/vibrations of the outer layer/ lipid layer 31 of the tear film to be measured . The amplitude/ strength of the detected surface vibration/expansion allows conclusions to be drawn about the concentration of absorbing molecules in the aqueous layer 32 of the tear film, and can therefore be used to analyze the concentration of the metabolites in the tear film 30 .

The light emitting and evaluation apparatus 20 is configured to emit light with a wavelength which is tuned to the wavelength-speci fic absorption of the molecules to be detected in the tear film 30 of the eye 2 . It is thus possible to excite speci fic molecules of interest in the tear film 30 and to determine their concentration . The wavelength of the emitted light can be adapted so that the detection scheme can be applied to nearly all sorts of molecules , for example vitamins , electrolytes , etc .

In particular, the light emitting and evaluation apparatus 20 is configured to emit light in the infrared ( IR) range or the near-infrared (NIR) range or the mid-infrared (MIR) range to excite speci fic molecules in the tear liquid . The molecules are metabolites and their concentration is an indication of the metabolic state of the body .

The light emitting and evaluation apparatus 20 is configured to be controlled to modulate the emitted light in amplitude which allows local expansion of the tear liquid due to molecular absorption to be modulated as well . The modulated expansion of the tear liquid leads to the vibration of the outer layer/ lipid layer 31 of the tear film 30 .

For SMI detection, the light emitting and evaluation apparatus 20 may be swept in wavelength . For this purpose , the light emitting and evaluation apparatus 20 is configured to be controlled to periodically change the wavelength of the emitted light . The wavelength of the emitted light is selected to be speci fic to the molecular absorption of the molecules to be detected in the tear liquid/ film 30 . By sweeping the emitted light in wavelength, the excitation of the molecules to be detected in the tear film 30 is modulated with the sweep frequency, for example , when the range of the wavelength to be swept is selected so that the molecular absorption is j ust at the edge of the wavelength sweep range .

The modulated excitation of the molecules to be detected in the tear liquid leads to a modulated local expansion of the tear liquid, and therefore to an oscillation of the lipid layer 31 on top of the tear film 30 . SMI detection is used by the light emitting and evaluation apparatus 20 to monitor this oscillation . For this purpose , the light emitting and evaluation apparatus 20 is configured to provide the SMI output signal with a level representing the strength/amplitude of surface vibrations of the lipid layer 31 of the tear film 30 which are caused by the excitation and absorption of the emitted light by the molecules to be detected in the tear film 30 . The oscillation amplitude of the surface vibrations of the lipid layer 31 is proportional to the molecule concentration in the tear liquid .

The light emitting and evaluation apparatus 20 uses the lipid layer 31 as an oscillating surface and measures the vibrations of that surface directly via sel f-mixing interferometry without involving a microphone . In conclusion, the measurement principle is based on the direct detection of the surface vibration of the lipid layer 31 of the tear film with SMI technology, but without the use of any extra microphone . The method is thus much more direct and therefore more sensitive than a comparable method using photo-acoustic spectroscopy .

Figure 3 shows an embodiment of the light emitting and evaluation apparatus 20 comprising a first light emitting device 21 and a second light emitting device 22 . The second light emitting device 22 is configured for emitting the light for the excitation of the molecules to be detected in the tear film 30 of the eye 2 .

The first light emitting device 21 is configured for emitting light towards the eye 2 . The light emitting and evaluation apparatus 20 is configured to evaluate an interference of the emitted light and the reflected light by sel f-mixing interferometry . The interference of the emitted light and the reflected light occurs inside the light emitting device 21 .

According to the embodiment shown in Figure 3 , the light emitting and evaluation apparatus 20 comprises separate light emitting devices 21 and 22 , wherein one of the light emitting devices 21 is configured for measuring the vibrations of the lipid layer 31 due to local expansion of the lipid layer via sel f-mixing interferometry . The other light emitting device 22 is provided for the excitation of the molecules to be detected in the tear film 30 .

The first light emitting device 21 is configured as a coherent light source , for example a laser light source . The light which is emitted by the first light emitting device 21 enters a cavity of the laser device after being reflected at the lipid layer 31 of the tear film 30 . The light emitting and evaluation apparatus 20 evaluates an interference of the light emitted by the first light emitting device 21 and the portion of the light reflected at the lipid layer 31 back into the cavity of the light emitting device/ laser device 21 by sel f-mixing interferometry .

The "disturbance" of the light emitting device/ laser device 21 by the back coupling leads to a change in laser threshold . According to a possible embodiment (voltage read out ) , the change in laser threshold can be detected in the voltage read out of the laser device 21 .

According to another possible embodiment (power read out ) , the light emitting and evaluation apparatus 20 comprises a read-out device in addition to the first light emitting device 21 . The signal develops in the cavity of the light emitting device/ laser device 21 but the pure intensity (power ) read-out is externally . The read-out device can be configured as a photodiode that may be mounted behind the first light emitting device/ laser device or next to the first light emitting device/ laser device . For example , i f the first light emitting device/ laser device 21 is configured as a VCSEL (back side emitting VCSEL ) , the read-out device/photodiode is mounted behind the VCSEL or next to the VCSEL .

The second light emitting device 22 may be configured as a non-coherent light source , for example a non-coherent IR, NIR, or MIR light source for exciting the molecules in the tear liquid . Since these light sources are more broad band in their emission, a Fabry-Perot cavity or an interference filter can be added to lower the emission bandwidth .

Especially in the case of the Fabry-Perot cavity, it can be a tunable cavity to allow to tune to di f ferent molecular speci fic absorption wavelength and therefore excite several molecules in a separate way with only one light source .

Figure 4 shows another embodiment of the light emitting and evaluation apparatus 20 which comprises a single light emitting device 21 . The light emitting device 21 is configured to emit the light towards the eye 2 to excite the molecules to be detected in the aqueous layer 32 of the tear film 30 . The portion of the emitted light which is not absorbed by the molecules to be detected is reflected at the lipid layer 31 of the tear film 30 back into a cavity of the light emitting device 21 .

The light emitting and evaluation apparatus 20 is configured to provide the SMI output signal in response to the evaluation of the emitted light and the portion of the emitted light reflected back to the light emitting device 21 by sel f-mixing interferometry . The light emitting and evaluation apparatus 20 is configured to evaluate an interference of the light emitted towards the eye 2 for excitation of the molecules to be detected in the tear film 30 with the portion of the light reflected back from the tear film 30 of the eye by sel f-mixing interferometry . The interference occurs inside the light emitting device 21 .

The light emitting device 21 is configured to emit coherent light . In particular, the light emitting device 21 is configured as a laser light source . By using a coherent light source for the light emitting device 21 , it is possible to have molecule-speci fic excitation and surface vibrational detection carried out with one single device/ light source .

The light emitting and evaluation apparatus 20 shown in Figure 4 is thus based on a merge of an excitation and detection light source which leads to less power consumption as compared to the separate arrangement of a light emitting device 21 for SMI-based surface vibration detection and a light emitting device 22 for excitation of the molecules to be detected, as illustrated in Figure 3 .

Regarding the embodiment of the light emitting and evaluation apparatus 20 comprising the single light emitting device 21 , the interference of the emitted light and the reflected light inside the cavity of the light emitting device/ laser device 21 may be evaluated by the light emitting and evaluation apparatus 20 by voltage read-out or power read-out , as explained above .

Figure 5 shows an embodiment of a device 1 for detecting metabolic states in the eye . The device 1 comprises a frame 10 enabling the device to be worn on the head of a human or animal body . The device 1 further comprises the light emitting and evaluation apparatus 20 in one of the configurations described above with reference to Figure 3 and Figure 4 . The frame 10 has a support 11 for supporting the light emitting and evaluation apparatus 20 . The frame 10 further comprises a holding section 12 for holding the device on the head of a human or animal body .

The light emitting and evaluation apparatus 20 is arranged at the support 11 of the frame 10 so that the emitted light is directed towards the conj unctiva 40 or the iris 50 of the eye 2 . That means that the light is not emitted in the direction of the pupil 60 in order not to damage the optic nerves of the eye .

As illustrated in Figure 5 , the device 1 for detecting metabolic states in the eye may be configured as eye glasses , for example prescription glasses AR ( augmented reality) , VR (virtual reality) , or XR ( extended reality) goggles . The very small si ze of the light emitting and evaluation apparatus 20 allows the photo-vibrational detection scheme to be easily incorporated into the frame of eye glasses . By incorporating the light emitting and evaluation apparatus 20 into everyday worn glasses , a continuous monitoring of human or animal health markers contained in the tear liquid of the eye is enabled .

The device 1 enables non-invasive continuous health status and vital sign monitoring, particularly metabolic state monitoring ( fat versus sugar burning) or blood glucose monitoring by measuring vibrations of an outer layer/ lipid layer 31 of the tear film 30 of the eye triggered by the expansion of excited molecules in the tear liquid by using a surface vibrational spectroscopy technique based on sel fmixing interferometry .

The embodiments of the device for detecting metabolic states in the eye disclosed herein have been discussed for the purpose of familiari zing the reader with novel aspects of the device . Although preferred embodiments have been shown and described, many changes , modi fications , equivalents and substitutions of the disclosed concepts may be made by one having skill in the art without unnecessarily departing from the scope of the claims .

In particular, the design of the device for detecting metabolic states in the eye is not limited to the disclosed embodiments , and gives examples of many alternatives as possible for the features included in the embodiments discussed . However, it is intended that any modi fications , equivalents and substitutions of the disclosed concepts be included within the scope of the claims which are appended hereto .

Features recited in separate dependent claims may be advantageously combined . Moreover, reference signs used in the claims are not limited to be construed as limiting the scope of the claims .

Furthermore , as used herein, the term "comprising" does not exclude other elements . In addition, as used herein, the article "a" is intended to include one or more than one component or element , and is not limited to be construed as meaning only one . This patent application claims the priority of German patent application with application No. 102023109433.5, the disclosure content of which is hereby incorporated by reference .

References device for detecting metabolic states in the eye

2 eye frame support holding section light emitting and evaluation apparatus light emitting device light emitting device tear film lipid layer aqueous layer conj unctiva iris pupil

Claims

1. A device for detecting metabolic states in the eye, comprising :

- a frame (10) for wearing the device on a head of a human or animal body,

- a light emitting and evaluation apparatus (20) ,

- wherein the frame (10) has a support (11) for supporting the light emitting and evaluation apparatus (20) ,

- wherein the light emitting and evaluation apparatus (20) is configured for emitting light for excitation of molecules to be detected in the tear film (30) of the eye (2) ,

- wherein the light emitting and evaluation apparatus (20) is configured to generate an output signal in response to a detection of an interference of a portion of light reflected back from the eye (2) to the light emitting and evaluation apparatus (20) .

2. The device of claim 1, wherein the light emitting and evaluation apparatus (20) is arranged at the support (11) of the frame (10) so that the emitted light is directed towards the conjunctiva (40) or the iris (50) of the eye (2) .

3. The device of claim 1 or 2, wherein the light emitting and evaluation apparatus (20) is configured to emit the light in the infrared range or the near-infrared range or the mid-infrared range.

4. The device of any of the claims 1-3, wherein the light emitting and evaluation apparatus (20) is configured to emit the light with a wavelength being tuned to the wavelength specific absorption of the molecules to be detected in the tear film (30) of the eye.

5. The device of any of the claims 1-4, wherein the light emitting and evaluation apparatus (20) is configured to be controlled to modulate the emitted light in amplitude .

6. The device of any of the claims 1-5, wherein the light emitting and evaluation apparatus (20) is configured to be controlled to periodically change the wavelength of the emitted light.

7. The device of any of the claims 1-6, wherein the light emitting and evaluation apparatus (20) is configured to provide the output signal with a level representing the strength of surface vibrations of a lipid layer (31) of the tear film (30) of the eye (2) , the surface vibrations being caused by an excitation and absorption of the emitted light by the molecules to be detected in the tear film (30) of the eye (2) .

8. The device of any of the claims 1-7,

- wherein the light emitting and evaluation apparatus (20) comprises a light emitting device (21) being configured to emit the light for the excitation of the molecules and to receive reflected light being the portion of the emitted light that is reflected back to the light emitting device (21) ,

- wherein the light emitting and evaluation apparatus (20) is configured to evaluate an interference of the emitted light and the reflected light occurring inside the light emitting device (21) by self-mixing interferometry.

9. The device of claim 8, wherein the light emitting device (23) is configured to emit coherent light.

10. The device of any of the claims 1-7,

- wherein the light emitting and evaluation apparatus (20) comprises a first light emitting device (21) and a second light emitting device (22) ,

- wherein the first light emitting device (21) is configured for emitting light towards the eye (2) and to receive reflected light being a portion of the emitted light that is reflected back to the first light emitting device (21) ,

- wherein the light emitting and evaluation apparatus (20) is configured to evaluate an interference of the emitted light and the reflected light occurring inside the light emitting device (21) by self-mixing interferometry,

- wherein the second light emitting device (22) is configured for emitting the light for the excitation of the molecules to be detected in the tear film (30) of the eye (2) .

11. The device of any of the claims 1-10, wherein the device (1) is configured as eye glasses.

12. A method for detecting metabolic states in the eye, comprising :

- irradiating the eye (2) by emitting light towards the eye for excitation of molecules to be detected in the tear film (30) of the eye,

- evaluating a portion of light reflected back from the tear film (30) of the eye by self-mixing interferometry, - providing an output signal in response to the evaluation of the portion of light reflected back from the tear film (30) of the eye by self-mixing interferometry.

13. The method of claim 12, wherein an interference of light emitted towards the eye (2) for excitation of the molecules to be detected in the tear film (30) of the eye with the portion of light reflected back from the tear film (30) of the eye is evaluated by selfmixing interferometry.

14. The method of claim 12 or 13, wherein the light emitted towards the eye (2) is generated with a wavelength tuned to the wavelength specific absorption of the molecules to be detected in the tear film (30) of the eye .

15. The method of any of the claims 12-14, comprising: wherein the output signal is provided with a level representing the strength of surface vibrations of a lipid layer (31) of the tear film (30) , the surface vibrations of the lipid layer (31) being caused by the excitation and absorption of the emitted light by the molecules to be detected in an aqueous layer (32) of the tear film (30) .