WO2024005677A1

WO2024005677A1 - Methods and means for determining pupil size

Info

Publication number: WO2024005677A1
Application number: PCT/SE2022/050646
Authority: WO
Inventors: Peter ÖKVIST; Alexander Hunt; Martin Ek; Niklas LINDSKOG; Andreas Kristensson; Tommy Arngren
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2022-06-28
Filing date: 2022-06-28
Publication date: 2024-01-04

Abstract

A method for determining size of a pupil of an eye is provided. The method is performed in a smart contact lens placed on the eye and comprises transmitting at least one light signal through a light guiding means embedded in the smart contact lens, and determining, in a managing function arranged on the smart contact lens, real-time information on the pupil size based on feedback on the transmitted light signal. A smart contact lens, computer programs and computer program products are also provided.

Description

METHODS AND MEANS FOR DETERMINING PUPIL SIZE

TECHNICAL FIELD

The technology disclosed herein relates generally to the field of smart contact lenses, and in particular to means and methods for determining pupil size.

BACKGROUND

Contact lenses are thin, clear plastic discs worn in eyes to improve vision of a user. The contact lenses float on the tear film that covers the cornea of the eye. Similar to eyeglasses, they correct vision problems caused by refractive errors, that is, when the eye does not refract (bend or focus) light properly into the eye resulting in a blurred image. Besides such vision-correcting contact lenses, a variety of different types of contact lenses are known, for instance colored or tinted contact lenses, decorative (cosmetic) contact lenses, orthokeratology (Ortho-K) contact lenses, which are special gas-permeable lenses designed to reshape the cornea, implantable contact lenses (ICL), which are another type of contact lenses used for correcting the vision, but unlike traditional contact lenses, these are positioned such that they remain in the eye for a much longer period of time.

Smart contact lenses and their corresponding applications are examples of an emerging market expected to increase further; advances in wearable electronics, combined with wireless communications have triggered development of, for instance, health monitoring and medical treatment technologies. In this context, contact lenses and so-called smart contact lenses may find a wide range of applications.

One type of such smart contact lenses can deliver real-time information directly to the eyes of a user and, for instance, display text and images. Smart contact lenses with bio sensors and substance distributing capabilities are also known and typically used for measuring lactic acid, glucose, intraocular pressure, blood oxygen levels, pulse rate, etc. and other key metabolites detectable in tear fluids and/or by physical eye contact.

SUMMARY

The inventors of the herein presented teachings have noted that there would, in various situations, be useful to know the size of a pupil. There is thus a need for information regarding the size of the pupil, and in particular a current size of a varying pupil size. For example, a system that covers or conceals a presently exposed iris of the eye would benefit from knowing the current pupil size, and a system that needs to know the amount of light entering an eye globe would also benefit from knowing the pupil diameter.

There is thus a shortcoming of prior art in that there are no means for dynamically adapting the iris coverage/concealment to the pupil size that may vary for different reasons. Such dynamic adaptation is needed in order to ensure coverage of the whole iris without covering a varying pupil size.

There is thus a need for solutions for smart contact lenses to support a temporary coverage or concealment of a user’s iris without covering the pupil.

An objective of embodiments herein is to address and improve various aspects for smart contact lenses by enabling a temporary and/or dynamic iris coverage or concealment, wherein the coverage or concealment adapts to changes of the pupil size. This objective and others are achieved by the methods, devices, computer programs and computer program products according to the appended independent claims, and by the embodiments according to the dependent claims.

According to a first aspect there is presented a method for determining the size of a pupil of an eye. The method is performed in a smart contact lens placed on the eye and comprises the steps of providing for at least one light signal to pass through a light guiding means embedded in the smart contact lens, and determining, in a managing function arranged on the smart contact lens, real-time information on the pupil size based on feedback on the transmitted light signal.

The method, in various embodiments, provides several advantages. The size of a pupil diameter/radius is valuable information, for instance, for systems used with the aim to cover a presently exposed iris of the eye or to systems that need information regarding the amount of light entering the eye globe. As another example, the method is useful for e.g., a smart contact lens carrying iris disclosure and/or an iris-overlay pattern, and also for determining pupil dilation/iris size variations that are correlated with user-perceived complexity of mental tasks engagement. Still further, the method is useful in a smart contact lens also from a physical concealment aspect where the user may want to conceal a damaged iris or injury thereon and where the smart contact lens therefor would need to adapt the concealment based on the user’s pupil size.

The size of a pupil diameter/radius as such is valuable information, for instance for systems used with an aim to not only cover the iris but intentionally cover the pupil itself with the purpose of decreasing the optical aperture and increasing image sharpness of the eye.

According to a second aspect, a computer program for determining size of a pupil of an eye is provided. The computer program comprises computer code which, when run on processing circuitry on a smart contact lens, causes the smart contact lens to: provide for at least one light signal to pass through a light guiding means embedded in the smart contact lens, and determine, in a managing function arranged on the smart contact lens, real-time information on the pupil size and based on feedback on the transmitted light signal.

According to a third aspect, computer program product is provided comprising a computer program according to the second aspect, and a computer readable storage medium on which the computer program is stored.

According to a fourth aspect, a smart contact lens for determining size of a pupil of an eye is provided. The smart contact lens is configured to: provide for at least one light signal to pass through a light guiding means embedded in the smart contact lens, and to determine, in a managing function arranged on the smart contact lens, real-time information on the pupil size based on feedback on the transmitted light signal.

Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, apparatus, component, means, module, action, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, action, etc., unless explicitly stated otherwise. The actions of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

Figures 1 to 5 illustrate aspects of methods and of means according to embodiments;

Figure 6 is a flowchart of various aspects of a method according to embodiments;

Figure 7 is a schematic diagram showing functional units of a smart contact lens according to an embodiment;

Figure 8 is a schematic diagram showing functional modules of a smart contact lens according to an embodiment; and

Figure 9 shows one example of a computer program product comprising computer readable means according to an embodiment.

DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any action or feature illustrated by dashed lines should be regarded as optional.

Briefly, a method and means related to smart contact lenses are provided, that enables temporary and dynamic iris coverage and/or concealment that adapts to changes of the pupil size.

Existing technologies related to hard or soft electronic contact lenses are utilized, and the present teachings provide them with new features. For instance, for a smart contact lens carrying an iris disclosure and/or iris-overlay pattern the present teachings provides means for adapting the disclosure/pattern overlay to the current pupil size. Thereby the use of such disclosure/pattern overlay does not interfere with the user’s pupil dilation, i.e., when the pupil widens, the iris narrows and vice versa

As another example, the method disclosed herein may be used in a situation where detection of pupil dilation/iris size variations is correlated with user-perceived complexity of mental tasks (reflecting brain activity as cognitive load). The variation may be considered to determine the extent of pupil dilation attributable to a level of mental task engagement.

As yet another example, the method disclosed herein may be used in a smart contact lens for a physical concealment where the user may wish to, for instance, conceal a damaged iris or another eye injury. The method enables the smart contact lens to adapt to the user’s pupil size. The herein disclosed method hence finds many areas of use.

Fig. i illustrates aspects of a method and of means according to embodiments, and in particular an iris detection method and related means. A smart contact lens system io is shown comprising a smart contact lens 18 to be placed on an eye 22 of a user. The figure 1 shows the eye 22 in a sideview and an iris 24 and pupil 20 thereof. A light guiding means 12, 32 is used to provide for at least one light signal to pass therethrough. In this set of embodiments, the light guiding means 12 comprises an active light guiding means. The electronic component needed may be placed outside the largest expected pupil size, thereby reducing any negative impact on eyesight and visual quality that could else be caused by them. When the required electronic components are placed outside the field of view, less consideration to their optical properties is needed in the selection thereof.

In particular, according to this set of embodiments, the contact lens 18 is provided with a light guiding means 12 comprising a light emitter 14, exemplified in the following by an infrared (IR) emitter 14 and an IR sensor 16. Although IR light is used throughout the description as a preferred light wavelength, light of other wavelengths could alternatively be used. The IR emitter 14 provides for emitting the IR light signal through a light guiding means 12. The light guiding means 12 may, for instance, be a Holographic Optical Element (HOE), a waveguide or a prism. The light signal emitted from the IR emitter 14 travels through the light guiding means 12 and depending on the size of the pupil different responses, and thus results, are obtained. Figure 1 illustrates the case wherein the light signal Li (solid line) emitted from the IR emitter 14 is reflected at the iris 24, travels back to the IR sensor 16, which detects the light signal L2 (dotted line) with a light intensity Ri.

Fig. 2 illustrate aspects of the above described method and of means according to embodiments, and in particular the case wherein the light signal is not reflected at iris 24. In this case, the light signal emitted from the IR emitter 14 travels through the pupil 20 into a lens/vitreous body and is potentially fractionally backscattered by fundus of the eye 22. The light signal then travels back to the IR sensor 16, which detects the light signal with a light intensity R2. It is realized that the light intensity Ri, wherein the light signal is reflected at iris, is much larger than the light intensity R2 of the light signal travelling into pupil, i.e., Ri >> R2. The light signal could also be lost in the pupil 20, i.e., not reflected at all. In such cases, there is no return signal, i.e., the IR sensor 16 fails to detect a signal. Light intensity R2 is then interpreted to be zero. Essentially, presence of signal indicate that iris extends under the light guiding means 12, and if no measurement is received within a set time, it is interpreted as pupil extends under the light guiding means 12. In an embodiment, besides the illustrated IR sensor 16, an additional light sensor is used, facing outwards. The responses from these two sensors are compared and the light intensity R2 is determined based thereon.

In various embodiments, a managing function 15 is arranged on the smart contact lens 18. The managing function 15 receives the light signals and compares each signal’s relation to a configured light intensity of the iris reflection Ri and a configured light intensity of the no-iris reflection R2. The managing function 15 then establishes similarity of the current light signal with Ri or with R2. Based on this the managing function 15 then determines if the signal is associated with iris reflection or with no-iris reflection.

The managing function 15 may, for instance, associate an exit position of the light signal (photon) at the smart contact lens 18 with the determination of iris/no-iris, and based on this determine a location value at the lens, for instance as radius. The managing function 15 may then, for instance, adjust size of an iris concealment accordingly.

Fig. 3 illustrate aspects and embodiments of the described method and is a view from above of the sideviews shown in figure 1 and 2. The described method may be implemented by the light guiding means 12 comprising multiple light transmission and light reception paths. That is, an array of emitters and sensors maybe arranged on the smart contact lens 18, wherein each light transmission/reception path is associated with a respective pupil dilation and hence iris radius. The light from the emitter 14 travels to a sensing area of the light guiding means 12 and is reflected back to the sensor 16. The light guiding means 12 may, for instance, comprise a tapered HOE and a line array of associated IR transmitters 14 and sensors 16. In such embodiments, a line-resolution of an associated pupil dilation/iris position may be obtained. The signal managing function 15 on the smart contact lens 18 may then determine a position of the iris border with a higher resolution. It is noted that besides the light guiding means 12, the managing function 15 and other electronics are preferably placed outside of the user’s vision. The light guiding means 12 should cover part of the pupil 20 to be able to determine when light transmission is over the pupil 20.

Fig. 4 and Fig. 5 illustrate aspects of a method and of means according to various embodiments. Figure 4 is a sideview of a light guiding means, while Figure 5 shows it in a view from above. In this set of embodiments, the light guiding means 32, used for providing for at least one light signal to pass therethrough, is a shielded light sensor 32. In this set of embodiments, the light guiding means 32 comprises passive light guiding means, and the light signal may be the ambient light.

An embedded, e.g., in-molded, transparent conductor 32 such as, for instance, indium tin oxide (ITO) conductor can be used. The transparent conductor 32 may be provided with an embedded array of passive sensors connected to the conductor. The array is preferably designed as small and unintrusive as possible for the sight. The passive sensor may, for instance, comprise light sensor components 34a, 34b, 34c, 34d arranged thereon and each of them being shielded by a respective shielding 36a, 36b, 36c, 36d from light from outside. In a basic implementation, the light sensor components comprise a number of photo diodes 34a, 34b, 34c, 34d directed down towards the eye 22. Ambient light passes through the transparent conductor 32, between the shieldings 36a, 36b, 36c, 36d thereof. The transparent conductor 32 thereby provide for a number of light signals to pass therethrough, in particular at known locations. The light enters the eye 22 at different locations, and the photo diodes 34a, 34b, 34c, 34d send a respective analog signal back to a receiver 38 from the different positions of the transparent embedded conductor 32. The receiver 38 may comprise a number of comparators that provide a digital output corresponding to whether the photo diode at hand is above the iris or above the pupil, as exemplified next. As noted earlier, light that meet the pupil is absorbed in the eye, while light meeting the iris is reflected to some extent.

The combination of the digital output from the different photo diodes 34a, 34b, 34c, 34d will indicate the size of the pupil 20. The pupil size may, for example, be measured by comparing the analogue signal between two neighboring sensors 34a, 34b and then determine if the difference between these exceeds a threshold. For instance, if a signal from a first sensor 32a has a value about equal to a second sensor 32b, while the value from the second sensor 32b is much smaller than the value from a third sensor, the threshold for classifying the values to differ sufficiently much is exceeded between the second and the third sensors 32b, 32c. The digital output then indicates which sensor is the first sensor over the pupil and/or the last sensor over iris. Since the locations of the light sensor components 34a, 34b, 34c, 34d of the light guiding means 32, the border between the iris and the pupil may be determined by the managing function 15, and thus the radius of e.g., the pupil. The accuracy of such embodiments is limited by the distance between the light sensor components (e.g., photo diodes) on the transparent conductor 32.

In this set of embodiments, one sensor is used per position that is needed. The number of sensors that is needed maybe determined e.g., in view of desired accuracy or targeted resolution of the synthetic iris. If many radius/size-steps are required, a higher accuracy of the true-iris-tracking may be needed.

With reference to figures 1 and 3, the smart contact lens 18 may be part of a system 10. The system 10 then comprises the smart contact lens 18 and an external device 50, for instance a computer, a virtual machine in cloud, etc. The external device 50 is arranged to receive and/or transmit data from and/or to the smart contact lens 18 for processing of such data.

Fig. 6 is a flowchart of various aspects of methods according to embodiments. The features of the various embodiments that have been described may be varied and combined in many different ways, examples of which are given in the following.

A method 100 is thus provided for determining the size of a pupil 20 of an eye 22. The method 100 is performed in a smart contact lens 18 placed on the eye 22. It may, for instance, be performed in a managing function arranged on the smart contact lens 18. The managing function 15 may comprise a number of components, such as, for instance, optical components, electro-optical components and/or electronic components integrated in the substrate of the smart contact lens 18.

The method 100 comprises providing 102 for at least one light signal to pass through a light guiding means 12, 32. The light guiding means is provided in (e.g., embedded in) the smart contact lens 18. The light guiding means 12 may, for instance, comprise an array of Holographic Optical Elements (HOE), of different lengths, wherein the light signal may originate from an IR light source also arranged in the smart contact lens 18. As another example, the light guiding means 32 may simply comprise a number of light sensors 34a, 34b, 34c, 34d directed towards the eye 22 and a number of shielding means 36a, 36b, 36c, 36d arranged on a respective light sensor. Thereby outside light, such as sunlight, outside light or from any other light source is guided so as to pass between the shielding means 36a, 36b, 36c, 36d, while the outside light is hindered from passing through the shielding means 34a, 34b, 34c, 34d.

The method 100 comprises determining 104, in a managing function 15 arranged on the smart contact lens 18, real-time information on the pupil 20 size based on feedback on the transmitted light signal.

In an embodiment, the feedback used in the method 100 comprises feedback on the presence or absence of a reflection of the transmitted light signal. In such embodiments, the presence of reflection indicates that the light signal was reflected at the iris 24 and the absence of reflection indicates that the light signal was lost in the pupil 20. The method 100 further comprises an exit position of a light signal received at the smart contact lens 18. Examples of such embodiments were described in relation to figure 2. For instance, the managing function 15 in the smart contact lens 18 may compare the received light signal’s relation to light intensity of the iris reflection Ri and light intensity of the no-iris reflection R2, respectively. The managing function 15 may then establish similarity of the current light signal with Ri or with R2. Based on this the managing function 15 determines if the signal is associated with iris reflection or with no-iris reflection. Having this information and further having the exit position of the light signal, the location value on the smart

In some embodiments, the determining 104 comprises receiving the light signal in a detector 16 arranged on the smart contact lens 18, indicating that the light intensity is related to the iris reflection Ri,

- determining an exit position of the received light signal at the smart contact lens 18, and

- determining a radius of one or both of the pupil 20 and the iris 24 based on the exit position.

The method according to various embodiments, may detect a location of an inner radius in relation to a fixed point (starting point) of a used set-up. The fixed point/starting point may, for example, be the outer radius for the iris, which may be detected as a light-reflection at some line detector. In this procedure to find the starting point and when the outer radius of iris is to be found, a higher reflection value derives from a reflection at iris, and a lower value corresponding to light passing into eye-ball and not reflected at any underlaying iris, whereas the iris inner radius corresponds to a point in-between these two reflection/no-reflection samples.

In variations of the above set of embodiments, the exit position is determined as a value being larger or smaller than a radius Xi, wherein Xi is associated with a respective location on the light guiding means 12.

In various embodiments, the light guiding means 12 comprises an array of Holographic Optical Elements, HOE, of different lengths, each guiding light from an array of emitters 14 and back to an array of detectors 16. The array of emitters 14 and the array of detectors 16 are both arranged in the smart contact lens 18, and the method comprises determining the size of the pupil 20 based on length of the receiving HOE. It is noted that HOE is just one possible light guiding/wave guiding technology, used purely as an example, and that other technologies could equally well be used.

In various embodiments, the light signal is infrared, IR, the emitter 14 is an IR emitter, and the detector 16 is an IR detector.

In various embodiments, the light guiding means 12, 32 embedded in the smart contact lens 18 comprises a number of light sensors 34a, 34b, 34c, 34d directed towards the eye 22 and a number of shielding means(36a, 36b, 36c, 36d arranged on a respective light sensor and guiding outside light through the transparent conductor 32. In such embodiments, the feedback comprises data on whether a particular light sensor 34a, 34b, 34c, 34d is above the iris 24 or above the pupil 20.

In a variation of the above embodiment, the determining 104 comprises receiving, in a receiving device 38, an analogue signal sent from each of the light sensors 34a, 34b, 34c, 34d, and determining the size of the pupil 20 based on the received analogue signals.

In variations of the above embodiment, the receiving device 38 comprises a number of comparators providing a digital output, each digital output corresponding to an analogue signal from the respective light sensors 34a, 34b, 34c, 34d receiving or not receiving a reflection, and wherein the determining the size comprises finding two adjacent light sensors 34a, 34b, 34c, 34d having a signal difference higher than a set threshold.

In various embodiments, the method 100 is used for one or more of: adapting an iris coverage to changes of the size of the pupil 20; detecting pupil dilation variations of a user for correlation with perceived complexity of mental tasks; adapting content in a near-eye display.

Fig. 7 schematically illustrates, in terms of a number of functional units, the components of a smart contact lens 18 according to an embodiment. Processing circuitry 110 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 330 (illustrated in Fig. 9), e.g., in the form of a storage medium 130. The processing circuitry no may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

Particularly, the processing circuitry no is configured to cause the smart contact lens io to perform a set of operations, or actions, as disclosed herein. For example, the storage medium 130 may store the set of operations, and the processing circuitry 110 may be configured to retrieve the set of operations from the storage medium 130 to cause the smart contact lens 18 to perform the set of operations. The set of operations may be provided as a set of executable instructions. The processing circuitry 110 is thereby arranged to execute methods as herein disclosed.

The storage medium 130 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

The smart contact lens 18 may further comprise a communications interface 120 for communications with other entities, functions, nodes, and devices, over suitable interfaces. As such the communications interface 120 may comprise one or more transmitters and receivers, comprising analogue and digital components.

The processing circuitry 110 controls the general operation of the smart contact lens 18 e.g., by sending data and control signals to the communications interface 120 and the storage medium 130, by receiving data and reports from the communications interface 120, and by retrieving data and instructions from the storage medium 130. Other components, as well as the related functionality, of the smart contact lens 18 are omitted in order not to obscure the concepts presented herein.

Fig. 8 schematically illustrates, in terms of a number of functional modules, the components of a smart contact lens 18 according to an embodiment. The smart contact lens 18 of Fig. 8 comprises a number of functional modules; a transmit module 210 configured to transmit at least one light signal through a light guiding means embedded in the smart contact lens, and a determine module 220 configured to determine, in a managing function arranged on the smart contact lens, real-time information on the pupil size based on feedback on the transmitted light signal. The smart contact lens 18 of Fig. 8 may further comprise a number of optional functional modules, such as any of a module 230 configured to receive the light signal in a detector arranged on the smart contact lens, indicating that the light intensity is related to the iris reflection Ri, a module 240 configured to determine an exit position of the received light signal at the smart contact lens, and a module 250 configured to determine a radius of the pupil based on the exit position. In general terms, each functional module 210 - 250 may be implemented in hardware or in software. Preferably, one or more or all functional modules 210 - 250 may be implemented by the processing circuitry 110, possibly in cooperation with the communications interface 120 and the storage medium 130. The processing circuitry 110 may thus be arranged to from the storage medium 130 fetch instructions as provided by a functional module 210 - 250 and to execute these instructions, thereby performing any actions of the smart contact lens 18 as disclosed herein.

Fig. 9 shows one example of a computer program product 330 comprising computer readable means 340. On this computer readable means 340, a computer program 320 can be stored, which computer program 320 can cause the processing circuitry 110 and thereto operatively coupled entities and devices, such as the communications interface 120 and the storage medium 130, to execute methods according to embodiments described herein. The computer program 320 and/or computer program product 330 may thus provide means for performing any actions of the smart contact lens as herein disclosed.

In the example of Fig. 9, the computer program product 330 is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 330 could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 320 is here schematically shown as a track on the depicted optical disk, the computer program 320 can be stored in any way which is suitable for the computer program product 330. The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

1. A method (ioo) for determining size of a pupil (20) of an eye (22), the method (100) being performed in a smart contact lens (18) placed on the eye (22) and comprising:

- providing for (102) at least one light signal passing through a light guiding means (12, 32) embedded in the smart contact lens (18), and

- determining (104), in a managing function (15) arranged on the smart contact lens (18), real-time information on the pupil (20) size based on feedback on the transmitted light signal.

2. The method (100) as claimed in claim 1, wherein the feedback comprises:

- presence or absence of a reflection of the provided light signal, wherein the presence of reflection indicates that the light signal was reflected at the iris (24) and the absence of reflection indicates that the light signal was lost in the pupil (20), and

- exit position of a received light signal at the smart contact lens (18).

3. The method (100) as claimed in claim 1 or 2, wherein the determining (104) comprises:

- receiving the light signal in a detector (16) arranged on the smart contact lens (18), indicating that the light intensity is related to the iris reflection Ri,

- determining an exit position of the received light signal at the smart contact lens (18), and

- determining a radius of one or both of the pupil (20) and the iris (24) based on the exit position.

4. The method (100) as claimed in claim 3, wherein the exit position is determined as a value being larger or smaller than a radius Xi, wherein Xi is associated with a respective location on the light guiding means (12)

5. The method (100) as claimed in any of the preceding claims, wherein the light guiding means (12) comprises an array of Holographic Optical Elements, HOE, of different lengths, each guiding light from an array of emitters (14) and back to an array of detectors (16), the array of emitters (14) and array of detectors (16) both being arranged in the smart contact lens (18), and the method comprising determining size of the pupil (20) based on length of the receiving HOE. The method (ioo) as claimed in any of the preceding claims, wherein the light signal is infrared, IR; the emitter (14) is an IR emitter; the detector (16) is an IR detector. The method (100) as claimed in claim 1, wherein the light guiding means (12, 32) embedded in the smart contact lens (18) comprises a number of light sensors (34a, 34b, 34c, 34d) directed towards the eye (22) and a number of shielding means (36a, 36b, 36c, 36d) arranged on a respective light sensor and guiding outside light between the shielding means (36a, 36b, 36c, 36d), and wherein the feedback comprises data on whether a particular light sensor (34a, 34b, 34c, 34d) is above the iris (24) or above the pupil (20). The method (100) as claimed in claim 7, wherein the determining (104) comprises:

- receiving, in a receiving device (38), an analogue signal sent from each of the light sensors (34a, 34b, 34c, 34d), and

- determining the size of the pupil (20) based on the received analogue signals. The method (100) as claimed in claim 8, wherein the receiving device (38) comprises a number of comparators providing a digital output, each digital output corresponding to an analogue signal from the respective light sensors (34a, 34b, 34c, 34d) receiving or not receiving a reflection, and wherein the determining the size comprises finding two adjacent light sensors (34a, 34b, 34c, 34d) having a signal difference higher than a set threshold. The method (100) as claimed in any of the preceding claims, wherein the method (100) is used for one or more of: adapting an iris coverage to changes of the size of the pupil (20); detecting pupil dilation variations of a user for correlation with perceived complexity of mental tasks; adapting content in a near-eye display. A computer program (200) for determining size of a pupil (20) of an eye (22), the computer program comprising computer code which, when run on processing circuitry (110) of a smart contact lens (18), causes the smart contact lens (18) to:

- provide for at least one light signal to pass through a light guiding means (12, 32) embedded in the smart contact lens (18), and

- determine, in a managing function (15) arranged on the smart contact lens (18), real-time information on one or both of the pupil (20) size and iris (24) size based on feedback on the transmitted light signal. A computer program product (220) comprising a computer program (200) according to claim 11, and a computer readable storage medium (230) on which the computer program (200) is stored. A smart contact lens (18) for determining size of a pupil (20) of an eye (22), the smart contact lens (18) being configured to:

- determine, in a managing function (15) arranged on the smart contact lens (18), real-time information on the pupil (20) size based on feedback on the transmitted light signal. The smart contact lens (18) as claimed in claim 13, wherein the feedback comprises:

- exit position of a received light signal at the smart contact lens (18). The smart contact lens (18) as claimed in claim 13 or 14, configured to determine by:

- determining a radius of one or both of the pupil (20) and the iris (24) based on the exit position. The smart contact lens (18) as claimed in claim 15, wherein the exit position is determined as a value being larger or smaller than a radius Xi, wherein Xi is associated with a respective location on the light guiding means (12) The smart contact lens (18) as claimed in any of claims 13 - 16, wherein the light guiding means (12) comprises an array of Holographic Optical Elements, HOE, of different lengths, each guiding light from an array of emitters (14) and back to an array of detectors (16), the array of emitters (14) and array of detectors (16) both being arranged in the smart contact lens (18), and the method comprising determining size of the pupil (20) based on length of the receiving HOE.

18. The smart contact lens (18) as claimed in any of claims 13 - 17, wherein the light signal is infrared, IR; the emitter (14) is an IR emitter; the detector (16) is an IR detector.

19. The smart contact lens (18) as claimed in claim 13, wherein the light guiding means (12, 32) embedded in the smart contact lens (18) comprises a number of light sensors (34a, 34b, 34c, 34d) directed towards the eye (22) and a number of shielding means (36a, 36b, 36c, 36d) arranged on a respective light sensor and guiding outside light between the shielding means (36a, 36b, 36c, 36d), and wherein the feedback comprises data on whether a particular light sensor (34a, 34b, 34c, 34d) is above the iris (24) or above the pupil (20).

20. The smart contact lens (18) as claimed in claim 19, configured to determine by:

- determining the size of the pupil (20) based on the received analogue signals.

21. The smart contact lens (18) as claimed in claim 20, wherein the receiving device (38) comprises a number of comparators providing a digital output, each digital output corresponding to an analogue signal from the respective light sensors (34a, 34b, 34c, 34d) receiving or not receiving a reflection, and wherein the determining the size comprises finding two adjacent light sensors (34a, 34b, 34c, 34d) having a signal difference higher than a set threshold.

22. The smart contact lens (18) as claimed in any of claims 13 - 21, configured for use in one or more of: adaption of an iris coverage to changes of the size of the pupil (20); detection of pupil dilation variations of a user for correlation with perceived complexity of mental tasks; adaption of content in a near-eye display.