Device for myopia control using dynamic red light irradiation and associated method

Abstract

The invention relates to a device (2) for myopia control using red light irradiation, the device being intended to be placed at a predetermined distance in front of an eye (10) of a subject (1). The device comprises: - a light emitting module (21) configured to irradiate a region of the fundus (11) of the eye during an irradiation period with an emitted light having a first wavelength comprised between 600 nanometers and 680 nanometers, - a controller (22) configured to control the light emitting module, wherein the light emitting module comprises at least one light source (210) the controller is configured to modulate an intensity of the at least one light source in order for the light emitting module to be configured to irradiate a region of the fundus according to a dynamic irradiation pattern (12) during the irradiation period. The invention also relates to an associated method.

Description

[0001] Device for myopia control using dynamic red light irradiation and associated method

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The invention relates to a device for myopia control using dynamic red-light irradiation.

[0004] This device may be used to control and prevent myopia using repeated low-level red light therapy.

[0005] The invention also relates to an associated method using the device.

[0006] BACKGROUND INFORMATION AND PRIOR ART

[0007] Several options for myopia control, and thus myopia prevention, are available nowadays. These solutions often rely on slowing down / stopping an axial length elongation in myopic subjects, such as children for instance. This axial length measures the length of an eye, front to back.

[0008] These options for myopia control are classified broadly as optical and non-optical methods. Among the non-optical method, Repeated Low-level Red Light (RLRL) therapy is a treatment protocol wherein the subjects are exposed binocularly to low level laser light, with a wavelength comprised between 610 nanometers and 630 nanometers, for a period of about three minutes twice a day.

[0009] This method has shown significant results in myopia control and prevention, by slowing down the axial length elongation, through the irradiation of the retina, in particular, irradiation of an area around the foveal pit.

[0010] However, this treatment protocol has raised concerns regarding the safety of prolonged exposure to laser light. Indeed, although known red light therapy devices use laser light sources that are classified as class 1 in Europe, because the calculations provided to establish the safety class of a given light source are dependent on the pupil size, the classification of a laser light source may be unreliable.

[0011] For instance, a journal article “Ostrin, L. A., & Schill, A. W. (2024). Red light instruments for myopia exceed safety limits. Ophthalmic and Physiological Optics, opo.13272” has reported that commercially available red light therapy devices might exceed the maximum permissible exposure (MPE), which puts the retina at risk of photochemical and thermal damages. Indeed, the area around the foveal pit, which is exposed to the red light irradiation when using a red light therapy device, is particularly susceptible to damage to the retinal structures, due to a maximum permissible exposure reduced to less than one second.

[0012] SUMMARY OF THE INVENTION

[0013] Therefore, one object of the invention is a device for myopia control using dynamic red light irradiation to mitigate the safety issues related to red light therapy devices, by improving the myopia control effect and / or reducing the overall exposure received by the retinal region.

[0014] The above object is achieved according to the invention by a device for myopia control using red light irradiation, the device being intended to be placed at a predetermined distance in front of an eye of a subject. This device comprise:

[0015] - a light emitting module configured to irradiate a region of the fundus of the eye during an irradiation period with an emitted light having a first wavelength comprised between 600 nanometers and 680 nanometers,

[0016] - a controller configured to control the light emitting module, the light emitting module comprises at least one light source, the controller is configured to modulate an intensity of the at least one light source in order for the light emitting module to be configured to irradiate a region of the fundus according to a dynamic irradiation pattern during the irradiation period.

[0017] Thanks to the device described in the present disclosure, a given region of the fundus receives an overall reduced quantity of irradiation, due to the irradiation pattern being dynamic during the irradiation period. This allows the device to stay below the maximum permissible exposure limit, mitigating the risk of photochemical and thermal damages to the eye of the subject.

[0018] Other advantageous and optional features of the method according to the invention are as follows:

[0019] - the dynamic irradiation pattern is configured to induce a motion-based visual stimulus in the subject,

[0020] - the controller is configured to modulate the intensity of the at least one light source periodically in order for the at least one light source to perform blinking, the at least one light source being configured to reach a maximum intensity after an onset transition period and an intensity minimum after an offset transition period

[0021] - the onset transition period lasts at least 0.01 milliseconds and the offset transition lasts at least 8 milliseconds,

[0022] - the light emitting module comprises a plurality of light sources each light source being configured to irradiate a spot of the region of the fundus,

[0023] - the plurality of light sources comprises a first set of light sources each having a first maximum intensity and a second set of light sources each having a second maximum intensity, light sources in the first set of light sources are configured to irradiate spots of the fundus having an angular eccentricity relative to the fovea comprised between 6 degrees to 12 degrees, when the device is placed at the predetermined distance, the first maximum intensity being at least 10% higher than the second maximum intensity,

[0024] - a size of at least one light source in the plurality of light sources is determined according to the receptive field of the receptors comprised on the spot the at least one light source is configured to irradiate, the size of the at least one light source increasing as a an angular eccentricity relative to the fovea of the spot the at least one light source is configured to irradiate increases,

[0025] - light sources in the plurality of light sources are arranged along concentric circle,

[0026] - the controller is configured to modulate each light source of the plurality of light source with an identical phase and identical frequency,

[0027] - the light emitting module comprises groups of at least one light source, the controller is configured to modulate an intensity of each group in a synchronized manner compared to one another, so that a position of the region irradiated by the light emitting module moves across the fundus with a velocity under 10 degrees per second,

[0028] - the position of the region irradiated by the light emitting module moves with a velocity comprised between 1 degree per second and 3 degrees per second,

[0029] - the position of the region irradiated by the light emitting module is configured to move from a first region having a first angular eccentricity relative to the fovea toward a second region of the fundus having a second angular eccentricity, wherein the first angular eccentricity is higher than the second angular eccentricity,

[0030] - a center of the dynamic irradiation pattern is configured to irradiate a central region of the fundus and wherein a fixation pattern is placed at a center of the dynamic irradiation pattern,

[0031] - the device further comprises a processor and an image capture device, the processor being configured to process images acquired by the image capture device and being functionally connected to the controller, the controller being configured to control the light emitting device according to an information provided by the processor,

[0032] - the image capture device is configured to acquire an image of the pupil of the subject, the processor is configured to extract a size of the pupil of the subject and the controller is configured to adjust a maximum intensity of the light emitting module according to the size of the pupil,

[0033] - the image capture device is configured to acquire several images of the eye of the subject, the processor is configured to verify a positioning information of the subject, and the controller is configured to control the light emitting module according to the positioning information provided by the controller,

[0034] - the device is a head mounted device or a desktop device,

[0035] - the light emitting module comprises an OLED screen and / or a LED and / or a laser and / or a diffused light source combined with physical filters and masks and / or a light source combined with a screen with fluorescent dyes,

[0036] - the dynamic irradiation is configured to stimulate a motion based visual stimulus corresponding to a blinking motion, a looming motion, a receding motion, a spiraling motion, a random motion, a swinging motion, a clockwise motion, a counterclockwise motion, and / or a shifting motion.

[0037] The invention further relates to a method for myopia control using red light irradiation, said method comprising the following step:

[0038] - irradiating a region of the fundus of an eye of a subject during an irradiation period with light having a first wavelength comprised between 600 nanometers and 680 nanometers, the region being irradiated according to a dynamic irradiation pattern emitted by a light emitting module comprising at least one light source, an intensity of the at least one light source being modulated.

[0039] DETAILED DESCRIPTION OF EXAMPLE(S)

[0040] The following description with reference to the accompanying drawings will make it clear what the invention consists of and how it can be achieved. The invention is not limited to the embodiment illustrated in the drawings. Accordingly, it should be understood that where features mentioned in the claims are followed by reference signs, such signs are included solely for the purpose of enhancing the intelligibility of the claims and are in no way limiting on the scope of the claims.

[0041] In the accompanying drawings:

[0042] - Figure 1 (a) is a schematic side view of an eye of a subject and Figure 1 (b) is an embodiment of a device for myopia control and prevention according to the invention,

[0043] - Figure 2 is a schematic front view of the device for myopia control represented on figure 1 , the device comprises a controller and a light emitting module with light sources forming a pattern onto the module, an intensity of the light sources being controlled by the controller,

[0044] - Figure 3 illustrates an alternative embodiment for the pattern of the light emitting module of figure 2,

[0045] - Figure 4 illustrates another alternative embodiment for the pattern of the light emitting module of figure 2,

[0046] - Figure 5 shows an example of an intensity modulation as a function of time of the light sources of figure 2 when controlled by the controller,

[0047] - Figure 6 is another example of the intensity modulation imposed on the light sources of figure 2 by the controller,

[0048] - Figure 7 illustrates a temporal evolution of the pattern of the light emitting module with the intensity modulation of figure 6,

[0049] - Figure 8 is an illustration of a method using the device of figure 1.

[0050] In figure 1 , an eye 10 of a subject 1 is schematically represented, along with an embodiment of a device 2 for myopia control using red light irradiation according to the invention.

[0051] In the following, the term “myopia control” refers to both myopia control, i.e. slowing down myopia in a myopic subject 1 and prevention, i.e. preventing myopia from appearing in a non-myopic subject 1.

[0052] This device 2 is intended to be placed at a predetermined distance in front of the eye 10 of the subject 1. For instance, the device 2 can be placed at a distance comprised between 1 centimeter and 30 centimeters in front of a cornea of the eye 10 of the subject 1. This predetermined distance can be controlled either by an eye care practitioner, or the device 2 can be configured to lie in a specified position in relation to the subject 1 , through the help of stopping means placed accordingly.

[0053] For instance, in a first embodiment, the device 2 is a desktop device 2, intended to be place on a desk. In this case, the device 2 comprises a head rest onto which the subject 1 can place his / her head. In this case, the predetermined distance between the eye 10 of the subject 1 and the device 2 is at least 15 centimeters.

[0054] Alternatively, the device 2 is head-mounted, i.e. directly placed on the head of the subject 1 , and worn for the duration of the treatment protocol. For instance, the device can correspond to a virtual headset worn by the user. In this case, a distance between the eye 10 of the subject 1 and the device 2 is at least 2 centimeters.

[0055] The device 2 for myopia control using red light irradiation comprises a light emitting module 21 , a controller 22. Additionally, the device 2 may comprise an image capture device 23 and a processor 24.

[0056] The light emitting module 21 comprises at least one light source 210 and is configured to irradiate a region of a fundus 11 of an eye 10 of the subject 1 , as illustrated on figure 1. In particular, in the first embodiment, the device 2 for myopia control comprises two light emitting modules 21 , one for each eye 10 of the subject 1. These light emitting modules 21 are arranged accordingly, and can be connected to the same controller 22, or to two distinct controllers 22. Alternatively, the device 2 can comprise a single light emitting module 21. In this case, the treatment protocol can be applied to each eye 10 successively.

[0057] The fundus refers to the interior surface of the eye 10, which is opposite to the lens 13. The fundus includes the retina, the optic disc, the macula which comprises the fovea, etc. For instance, for red light therapy, the region of the fundus 11 irradiated by the light emitting module 21 is mainly comprised on the retina, more precisely comprised on the macula. The at least one light source 210 is configured to emit light referred to as red light. Hence, the light is emitted with a first wavelength comprised between 600 nanometers and 680 nanometers, which is typically perceived as red according to the human visual perception. Such a red light has myopia controlling properties when irradiated onto the fundus of the eye 10 of a subject 1 , by influencing the axial length elongation for instance.

[0058] In a variant, the first wavelength is comprised between 600 nanometers and 680 nanometers, or between 600 nanometers and 630 nanometers, or between 610 nanometers and 630 nanometers.

[0059] For instance, in the first embodiment of the device 2 according to the invention, the at least one light source 210 emits light at a first wavelength of 620 nanometers and has a bandwidth of 20 nanometers. Hence, the at least one light source 210 emits light with wavelengths ranging between 610 nanometers and 630 nanometers.

[0060] By light source 210 it is referred to an individual means configured to emit light at the required wavelength. For instance, by light source 210 it is referred to, in the first embodiment, to adjacent pixels 30 of an OLED display that are backlit to act as a single light source 210 (see figure 2). Indeed, the adjacent pixels 30 are configured to emit light with the required first wavelength. Said otherwise, in this first embodiment, the at least one light source 210 corresponds to adjacent pixels 30 that are turned on. In this embodiment, the OLED display acts as the light emitting module 21 . For instance, in the first embodiment the device 2 comprises two digital OLED displays (one for each eye), that is enclosed in a desktop device or a head-mounted device. Alternatively, each eye may be stimulated in a distinct manner, i.e. , one after the other, in which case, the device would comprise a single digital OLED display. In yet another alternative, the device 2 comprises a single OLED display which is wide enough to be divided into two portions, one for each eye. A divider can be added to the device, to isolate the two portions of the OLED display.

[0061] In other embodiments, the at least one light source 210 refers to a light-emitting diode (commonly known as a LED) which is arranged onto a circuit board comprised in the light emitting module 21 , and / or to a laser diode arranged onto a circuit board.

[0062] In yet another embodiment, the device 2 comprises a uniform light source, also referred to as a diffused light source, which emits, in a first variant, light at the required wavelength. This light source is then combined with physical filters and a mask, the mask comprising apertures through which the light emitted by the uniform light source passes through. In this case, each of these apertures acts as a light source 210 as defined above. In another variant, the uniform light source is configured to emit light at a wavelength that is shorter compared to the first wavelength, in order to illuminate a fluorescent material. Here, the fluorescent material is a fluorescent dye. For instance, the light emitted by the uniform light source has a wavelength of 400 nanometers (which corresponds to blue light, as perceived by the human vision). This fluorescent material is configured to emit light at the first wavelength when illuminated by the uniform light source. In this variant, a pattern would be drawn on a screen using the fluorescent dye, in order to emit red-light when illuminated by the uniform light source. In this case, the at least one light source 210 is identified as the pattern obtained through the fluorescent dye illuminated by the uniform light source.

[0063] The at least one light source 210 comprises either a single light source 210 or a plurality of light sources 210.

[0064] In particular, in the case wherein the light emitting module 21 comprises a plurality of light sources 210 each light source 210 of the plurality of light sources 210 can be chosen among one of the possible light sources 210 previously described. For instance, the light emitting module 21 can comprise several different types of light sources 210 i.e. a light emitting module 21 can comprise both at least one LED and at least one laser diode. Alternatively, the light emitting module 21 can also comprise both an OLED display and at least one LED and / or laser diode.

[0065] If the light emitting module 21 comprises several light sources 210 each of the light sources 210 can either emit at the same wavelength, i.e. the first wavelength. However, the light emitting can also comprise at least one light source 210 that emits at the first wavelength and at least one light source 210 that emits at a different second wavelength. For instance, the light emitting module can comprise at least one light source that emits cyan light, i.e. light with the second wavelength comprised between 460 nanometers to 520 nanometers. In this case, the subject 1 would receive both red light and cyan irradiation.

[0066] Here, in the first embodiment illustrated on figure 1 and figure 2, the light emitting module 21 comprises a plurality of light sources 210 which are arranged on the light emitting module 21 to form a pattern 211 .

[0067] For instance, as the light emitting module 21 comprises an OLED display, the number of light sources 210 in the plurality of light sources 210 depends on the number of groups of adjacent pixels 30 that are turned on, each group of adjacent pixels 30 corresponding to one of the light sources 210

[0068] Alternatively, if the light emitting module 21 comprises a plurality of light-emitting diodes and / or laser diode, each light-emitting diode and / or laser diode corresponds to a light source.

[0069] One example of the pattern 211 formed by the light sources 210 on the light emitting module 21 according to the first embodiment is represented on figure 2.

[0070] In this first embodiment, the light sources 210 are arranged along concentric rings 213, with a regular or irregular spacing between each adjacent light source 210 in a ring 213, and a regular or irregular spacing between rings 213. A size of each light source 210 is fixed or adjustable. For instance, in the first embodiment, the size of each light source

[0071] 210 is defined according to an extent of a visual field, as detailed later in this description.

[0072] In practice, for the light sources 210 to form the pattern 211 on the light emitting module 21 in the first embodiment (i.e. the OLED display), groups of adjacent pixels 30 are turned on accordingly. Advantageously, using a programmable light emitting display such as the OLED display of the first embodiment allows for an easier control over the pattern

[0073] 211 formed onto the light emitting module 21 by the light sources 210, simply by programming which pixels 3 of the display are on and off.

[0074] Other possible embodiments for the arrangement of the plurality of light sources 210 on the light emitting module 21 , and thus, other possible patterns 211 are shown in figures 3 and 4.

[0075] The pattern 211 formed on the light emitting module 21 either has rotational symmetry, as in the embodiments presented above, or has no rotational symmetry, therefore being asymmetric or has no symmetry at all. For instance, in a possible embodiment, the light sources 210 are arranged along a line, a square, etc.

[0076] A spatial arrangement, i.e., a disposition of the light sources 210 on the light emitting module 21 is for instance fixed. Said otherwise, a disposition of given light source 210 remains the same on the light emitting module 21. This is, for example, when the light emitting module 21 comprises light-emitting diodes and / or laser diodes, as each element is welded at a defined position on the circuit board.

[0077] Alternatively, a disposition of the light sources 210 on the light emitting module 21 is easily changed, for instance, when the light emitting module 21 comprises an OLED display, depending on which pixels 3 are on or off, the spatial arrangement of the light sources 210 on the light emitting module 21 is easily modified. It is also the case when the light source 210 is obtained by combining a uniform light source with a spatial filter and mask, as this spatial filter and mask can be moved to displace a position of the at least one light source 210 obtained through the aperture or apertures of the mask.

[0078] Each light source 210 of the light emitting module 21 is configured to have a maximum intensity Imax and a minimum intensity Imin. The value of the maximum intensity Imax is determined according to a recommended maximum permissible exposure (MEP). For instance, the minimum intensity Imin refers to a state wherein the light source 210 is turned off, i.e. the light source 210 does not emit light. On the contrary, the light source 210 is considered to be turned on when its intensity is above the minimum intensity Imin and below or equal to the maximum intensity Imax.

[0079] For instance, each light source 210 of the light emitting module 21 has the same maximum intensity Imax and the same minimum intensity Imin. In other possible embodiments, light sources 210 may have different maximum intensity Imax and / or minimum intensity Imin.

[0080] The controller 22 is configured to control the light emitting module 21 , by modulating an intensity of the light sources 210 or intensities of the plurality of light source 210 during the irradiation period Tjrr. In other words, the controller 22 controls the intensity of each light source 210 of the light emitting module 21 as a function of time during an irradiation period Tjrr.

[0081] The irradiation period Tjrrcorresponds to a prescribed duration during which the device 2 for myopia control is used by the subject 1 . For instance, for repeated low-level red light therapy, the irradiation period Tjrrfor each eye 10 lasts about three minutes.

[0082] The light emitting module 21 controlled by the controller 22 is configured to irradiate a region of the fundus 11 according to a dynamic irradiation pattern 12 projected on the fundus.

[0083] The irradiation pattern is referred to as “dynamic” as the controller 22 modulates an intensity of at least part of the light sources 210 as a function of time, during the irradiation period Tjrr. Therefore, during the irradiation period Tjrr, the controller 22 controls the intensity of the light source(s) of the light emitting module 21 to fluctuate in a perceivable or imperceivable manner for the subject 1.

[0084] The dynamic irradiation pattern 12 is an image of the light emitting module 21 formed onto the fundus by the lens 13 of the eye 10 of the subject 1 , as the eye 10 acts as an imaging device 2, wherein the lens 13 of the eye 10 corresponds to an optic lens. In other words, the lens 13 of the eye 10 of the subject 1 images the at least one light source 210 of the light emitting module 21 onto the region of the fundus 11 the light emitting module 21 is configured to irradiate. The light emitting module 21 is imaged onto the fundus with a given magnification.

[0085] In practice, given that the light emitting module 21 comprises a plurality of light sources 210 in the first embodiment, each light source 210 of the plurality of light sources 210 is individually imaged onto the fundus. Therefore, each light source 210 of the plurality of light sources 210 is configured to irradiate a spot 120 of the region of the fundus 11. Each of the spots 120 is associated with a position on the fundus. This position is, for instance, associated with a geometrical center of the spot 120. Together, these spots 120 form the dynamic irradiation pattern 12.

[0086] For repeated low red light therapy, the device 2 for myopia control specifically targets the region of the fundus 11 corresponding to the macula. The macula comprises concentric regions, the perifovea being the outermost region, followed by the parafovea and, at the center, the fovea. Positions on the fundus, more specifically, positions on the macula are described with an angular eccentricity E relative to the center of the fovea, which acts as the 0 degree reference. Values of angular eccentricity E, provided in angles, are defined as an angle about the axis connecting the center of the fovea, and the center 14 of the eye 10. An example of such an angle is shown in figure 1 , under the reference E.

[0087] Here, given that the pattern 211 on the light emitting module 21 in the first embodiment has rotation symmetry, a position on the fundus of each spot 120 associated with a given light source 210 is simply defined by its angular eccentricity E.

[0088] As the dynamic irradiation pattern 12 on the fundus and the pattern 211 formed by the light sources 210 on the light emitting module 21 are conjugated with one another, if not specified otherwise, both patterns may be referred as the dynamic irradiation pattern. Indeed, a change in the pattern 211 on the light emitting module 21 implies that the dynamic irradiation pattern 12 changes as well.

[0089] A center of the dynamic irradiation pattern 12 is configured to irradiate the fovea, especially, the center of the fovea (i.e., the fovea centralis). In other words, the conjugated spot 120 would have an angular eccentricity E of 0 degrees. This is illustrated by figure 2.

[0090] In the first embodiment (figures 1 and 2), a light source 210 is placed at the center of the dynamic irradiation pattern 12 and acts as a fixation pattern 214. This light source

[0091] 210 is imaged through the eye 10 to form a spot 120 at the center of the fovea. This fixation pattern 214 is meant for the subject 1 to focus his / her attention on for the duration of the treatment protocol. This ensures a correct gaze position and eye 10 placement during the irradiation period Tin, in order for the subject 1 to receive an appropriate amount of light for the myopia control effect.

[0092] In another embodiment, the light source 210 placed at the center of the pattern

[0093] 211 may be replaced by an image displayed by a screen, for instance an OLED screen. This image would then serve as the fixation pattern 214.

[0094] In yet another embodiment, the center of the dynamic irradiation pattern 12 is left empty. This embodiment is advantageous in order to reduce the overall amount of irradiation received by the subject 1 , and thus lower the risk of photodamages and / or thermal damages.

[0095] The size of each light source 210 is either fixed or is adjusted depending on the position of the spot 120 on the fundus generated by the considered light source 210. For instance, in the first embodiment illustrated on figure 1 and figure 2, the size of the light sources 210 is determined according to the receptive fields of the receptors comprised on the associated spot 120 of the fundus. The receptive fields of the receptors are defined as volumes in visual space. The variation of the receptive fields of the receptors throughout the fundus is well documented.

[0096] In this embodiment, the size of the light source 210 is determined according to the value of the angular eccentricity E of the resulting spot 120 on the fundus. In the example provided on figure 1 , the size of the light sources 210 increases as the angular eccentricity E of the resulting spots 120 increases. Indeed, when moving from the fovea to the outermost part of the macula, the size of the receptive field increases from 1 arc minute at the center of the fovea to around 7 degrees. This change in the sizes of the receptive field is due to a decrease in a density of light receptors when far from the fovea.

[0097] To match this increase of the size of the receptive fields when the angular eccentricity £ increases, dimensions of the spot 120 vary from 0.8 degree to 2.8 degrees at the edges. Sizes of the light sources 210 on the light emitting module 21 are determined accordingly. Matching the size of the light sources 210 and the size of the receptive field advantageously ensures an optimal response of the light receptors.

[0098] In other possible embodiments, such as those represented on figure 3 and 4, the size of the light sources 210 and their resulting spots 120 remains identical for all light sources 210 of the light emitting module 21.

[0099] In order to increase an efficiency of the myopia control effect provided by the device 2 according to the invention, the light emitting module 21 is for instance configured to target specific regions of the fundus.

[0100] By targeting, it means to either only irradiate these specific regions, or to irradiate them with an increased intensity compared to other regions of the fundus.

[0101] In particular, instead of mainly irradiating the center of the fovea, which poses a risk of light induce damages due to the low value of the MEP in this area, another sub region receives the most irradiation. This sub-region is for instance the mid-peripheral retinal region, which corresponds to a region with an angular eccentricity £ comprised between 6 degrees and 12 degrees from the fovea.

[0102] According to a possible embodiment, all light sources 210 of the light emitting module 21 are arranged to specifically irradiate the mid-peripheral region.

[0103] According to another embodiment which is illustrated on figure 3, the value of the maximum intensity Imax of the light sources 210 configured to irradiate the mid-peripheral retinal region is increased compared to the intensity of other light sources 210. For instance, in this embodiment, the plurality of light sources 210 comprises a first set 215 of light sources 210 with a first maximum intensity Imax and a second set 216 of light sources 210 with a second maximum intensity Imax. Light sources 210 from the first set 215 are arranged on the light emitting module 21 , in order to irradiate spots 120 on the fundus which have an angular eccentricity £ relative to the fovea comprised between 6 degrees and 12 degrees. Meanwhile, light sources 210 from the second set 216 irradiate other distinct regions of the fundus. According to this embodiment, the first maximum intensity Imax is at least 10%, at least 20%, at least 30%, at least 40% higher than the second maximum intensity Imax. An example of this embodiment is illustrated on figure 2.

[0104] Advantageously, increasing an efficiency of the treatment protocol on the subject 1 allows to shorten the irradiation period Tjrrneeded, and / or reduce the exposure of the subject 1 to risks of damage induces by the light and ensuring the device 2 stays below the recommended MEP, and / or improve the result obtained on the subject 1 using the device 2.

[0105] Increase in the efficiency of the treatment protocol is also achieved by using a dynamic irradiation pattern 12 that is configured to induce a motion based visual stimulus in the subject 1. Indeed, although an unperceivable intensity modulation is beneficial in order to reduce the overall quantity of light received by the subject 1 , which in turn lowers the requirements on the device 2 regarding the MEP, inducing a motion based visual stimulus, also called a motion perception, in the subject 1 is advantageous to increase the efficiency of the treatment protocol. This shortens the irradiation period Tjrrneeded, and / or reduces the exposure of the subject 1 to risks of damage induces by the light, for instance by reducing the maximum intensity I max required, and / or improve the result obtained on the subject 1 using the device 2.

[0106] Indeed, like the unperceivable intensity modulation, inducing a motion based stimulus reduces the overall amount of light received by the subject 1 during the irradiation period Tjrr.

[0107] Moreover, slow motions are known to activate an ON-pathway for the processing of the resulting visual stimulus, as reported in Luo-Li, G., Mazade, R., Zaidi, Q., Alonso, J.- M., & Freeman, A. W. (2018). Motion changes the response balance between ON and OFF visual pathways. Communications Biology, 1(1), 60. Stimulation of the ON and as well as of the OFF pathway can be measured through electrophysiology or psychophysics. Activation of the ON-pathway may be beneficiary for myopic subject 1 and may produce a myopia control effect. In particular, activation of the ON-pathway compared to the OFF- pathway in the subject 1 can be used to correct an imbalance between the ON and OFF pathways observed in myopic subject 1. Hence, inducing a motion based visual stimulus in the subject 1 can enhance the effectiveness of the treatment protocol, with the benefits listed above.

[0108] The motion refers to a motion, for instance a blinking or a spatial displacement, of the at least one light source 210 controlled by the controller 22. Such motion, i.e. motions that elicit a motion-based visual stimulus in the subject 1 , are well known. Here, these motions are generated through the modulation of the intensity of the light source(s) comprised in the light-emitting module 21.

[0109] Figure 5 represents an example of the intensity modulation as a function of time for a light source 210 controlled by the controller 22. For instance, the at least light one light source 210 is configured to blink during the irradiation period Tjrr. In this case, the controller 22 is configured to modulate the intensity of the at least one light source 210 periodically, so that the light source 210 would blink. By blinking, it is meant that the at least one light source 210 is configured to reach the maximum intensity I max after an onset transition period TON and the intensity minimum after an offset transition period TOFF. TO further activate the ON-pathway, the blinking advantageously has a sudden onset and a gradual offset. In other words, the onset transition period TON is shorter than the offset transition period TOFF. For instance, the onset transition period TON lasts between 0.01 millisecond and 1 millisecond, preferably between 0.5 millisecond and 1 millisecond, and the offset transition period TOFF lasts at least 8 milliseconds.

[0110] When the light emitting module 21 comprises a plurality of light sources 210 the motion induced visual stimulus can also refer to a spatial motion, wherein lights sources move across the subject’s visual field. For instance, in the case where the dynamic irradiation pattern 12 has rotational symmetry, the subject 1 sees a looming motion wherein light sources 210 are gradually turned on and off from the center of the irradiation pattern toward the outermost edges of the irradiation pattern. Alternatively, the subject 1 may see a receding motion, wherein light sources 210 are gradually turned on and off starting from the outermost edges of the dynamic irradiation pattern 12 toward the center. Another possible motion would be a drifting motion, wherein the subject 1 sees at least a light source 210 shifting between the right and left sides of his / her visual field. Other possible motions includes clockwise and counterclockwise motion, spiral motion, swinging motion, random motion... Throughout the irradiation period, the light emitting module 21 can also display several types of motions in succession to one another.

[0111] Advantageously, the motion-based visual stimulus is seen as slow by the subject 1 . The motion of the irradiated region on the fundus has a slow velocity. For instance, the velocity of the motion is under 10 degrees per second, or between 1 degree per second and 3 degrees per second. As the light sources 210 are turned on and off in a rhythmic manner, at a given moment, a defined region of the fundus 11 is irradiated according to a given irradiation pattern. This given irradiation pattern for this moment is defined by which light sources 210 are on, and which are off. The irradiation pattern changes during the irradiation period Tin, thanks to the controller 22 that modulates the intensity of the light source.

[0112] To induce such a spatial motion, light sources 210 of the light emitting are turned on and off in a synchronized and orderly manner by the controller 22. For instance, light sources 210 of the plurality of light sources 210 are organized according to groups 2171 , 2172, 2173, 2174, 2175, 2176, 2177. These groups 2171 , 2172, 2173, 2174, 2175, 2176, 2177 are illustrated on figure 7. The controller 22 then modulates an intensity I2171 , I2172, I2173, 12174, 12175, 12176, 12177 of each group in a synchronized manner, meaning all light sources 210 in a group are modulated in the same manner, timing-wise. However, light sources 210 in a group may have different maximum and minimum intensities.

[0113] In the first embodiment represented by figures 1 , 2, 6 and 7, light sources 210 in a given concentric ring 214 belong to a same group. In this illustration, the light emitting module 21 comprises seven groups 2171 , 2172, 2173, 2174, 2175, 2176, 2177 of light sources 210 which are numbered starting from the outermost ring, toward the center of the irradiation pattern. An example of the intensity modulations generated by the controller 22 for these groups is shown in figure 6. In order to induce the motion-based visual stimulus in the subject 1 starring the light emitting module 21 , here, a looming motion, light sources 210 are consecutively turned on then off, depending on their respective group.

[0114] A corresponding temporal evolution of the dynamic irradiation pattern 12 is shown on figure 7. This temporal evolution illustrates each group 2171 , 2172, 2173, 2174, 2175, 2176, 2177 of light sources 210 being turned on and off in succession.

[0115] Thanks to different aspects and / or their combination of the invention, the device 2 for myopia control makes it easier to stay below a safety threshold imposed by the maximum permissible exposure. Indeed, using a dynamic irradiation pattern 12 lowers the cumulated quantity of irradiation a given region of the fundus 11 is exposed to, through either spatial and / or time modulation of the spots 120. Furthermore, it may lower the overall quantity of irradiation received and / or the duration of the irradiation period Tin, thanks to a more efficient therapeutic effect on the subject 1.

[0116] The eye 10 safety of the subject 1 is also protected by targeting specific subregions of the fundus, wherein the MEP is higher.

[0117] Advantageously, using an OLED screen as the light emitting module 21 instead of laser diodes further protects the subject 1.

[0118] Additionally, the value of the maximum intensity Imax of the light sources 21 Ois adapted to the subject 1 , in order to stay below the MEP.

[0119] For instance, the device 2 for myopia control using red light irradiation can further comprise a processor 24 and an image capture device 23. The image capture device 23, for instance a color camera, is configured to acquire an image of the pupil of the subject 1. This image is then analyzed using the processor 24, using image processing algorithms to retrieve a pupil size, for instance, a diameter or a radius of the pupil. As the MEP is established using the pupil size, a corrected MEP is determined using the subject’s pupil size, instead of a default value.

[0120] An effective maximum intensity Imax of the light sources 210 is then adjusted by the controller 22 taking into account the corrected MEP provided by the processor 24.

[0121] The image capture device 23 and the processor 24 are also used to verify a positioning information of the subject 1. To do so, several images of the eye 10 of the subject 1 are acquired and processed by the processor 24 using appropriate image processing algorithms.

[0122] The light emitting module 21 can be controlled according to the positioning information provided by the subject 1 . For instance, the light emitting can be turned off as a whole if the positioning information is deemed incorrect, i.e. the subject 1 is not positioned properly, or is not starring at the fixation pattern 214. This limits the risk of unwanted irradiation and protects the safety of the subject 1 .

[0123] Advantageously, the positioning information of the subject 1 can be further used to assess a positioning of the gaze of the subject and thus provide a rough positioning of the center of the fovea while the subject 1 is looking at the light emitting module 21 during the irradiation period. This information can then used to determine a quantity of motion perceived by the subject 1 , the motion being induced by the dynamic irradiation pattern 12, thanks to the modulation of the intensity of the light source(s) on the light emitting module 21 . More specifically, the knowledge of the relative positioning between the fovea and the varying light source(s) during the irradiation period, makes it possible to quantify the motion perceived by the subject 1 , in a well-known manner. Indeed, said motion perception mechanism is well known, and despite a small degree of individual variability, certain patterns, here created through modulating light intensity of the light source(s), are known to elicit motion perception in a healthy subject.

[0124] This device 2 is meant to implement a method for myopia control using red light irradiation. Figure 8 illustrates this method. It comprises a step 100 of irradiating a region of the fundus 11 of an eye 10 of a subject 1 during an irradiation period Tjrrwith light having a first wavelength comprised between 600 nanometers and 680 nanometers, this region being irradiated according to a dynamic irradiation pattern 12 emitted by a light emitting module 21 comprising at least one light source 210 an intensity of said at least one light source 210 being modulated. Additionally, the method can comprise a step 101 of acquiring an image of the pupil of the subject 1 , which is then used to establish the corrected value of the MEP, as described above. Another additional step 102 corresponds to the acquisition of several images of the eye 10 of the subject 1. These images are then analyzed to determine if the subject 1 is properly positioned for the treatment protocol. In all cases, these additional steps are accompanied by a step 103 of adjusting the effective maximum intensity Imax of the light sources 210 using the controller 22.

Claims

CLAIMS

1. Device (2) for myopia control using red light irradiation, said device (2) being intended to be placed at a predetermined distance in front of an eye (10) of a subject (1), comprising:- a light emitting module (21) configured to irradiate a region of the fundus (11) of the eye (10) during an irradiation period (Tjrr) with an emitted light having a first wavelength comprised between 600 nanometers and 680 nanometers,- a controller (22) configured to control the light emitting module (21), characterized in that the light emitting module (21) comprises at least one light source (210) the controller (22) is configured to modulate an intensity of the at least one light source (210) in order for the light emitting module (21) to be configured to irradiate a region of the fundus (11) according to a dynamic irradiation pattern (12) during the irradiation period (Tjrr).

2. The device (2) according to claim 1 , wherein said dynamic irradiation pattern (12) is configured to induce a motion-based visual stimulus in the subject (1).

3. The device (2) according to any one of claim 1 or 2, wherein the controller (22) is configured to modulate the intensity of the at least one light source (210) periodically in order for the at least one light source (210) to perform blinking, the at least one light source (210) being configured to reach a maximum intensity I max after an onset transition period and an intensity minimum after an offset transition period.

4. The device (2) according to claim 3, wherein the onset transition period lasts at least 0.01 milliseconds and the offset transition lasts at least 8 milliseconds.

5. The device (2) according to any one of claims 1 to 4, wherein the light emitting module (21) comprises a plurality of light sources (210) each light source (210) being configured to irradiate a spot (120) of the region of the fundus (11).

6. The device (2) according claim 5, wherein the plurality of light sources (210) comprises a first set (215) of light sources (210) each having a first maximum intensity and a second set (216) of light sources (210) each having a second maximum intensity, light sources (210) in the first set (215) of light sources (210) are configured to irradiate spots (120) of the fundus having an angular eccentricity (E) relative to the fovea comprised between 6 degrees to 12 degrees, when the device(2) is placed at the predetermined distance, the first maximum intensity being at least 10% higher than the second maximum intensity.

7. The device (2) according to any one of claim 5 or 6, wherein a size of at least one light source (210) in the plurality of light sources (210) is determined according to the receptive field of the receptors comprised on the spot (120) said at least one light source (210) is configured to irradiate, the size of the at least one light source (210) increasing as a an angular eccentricity (E) relative to the fovea of the spot (120) said at least one light source (210) is configured to irradiate increases.

8. The device (2) according to any one of claims 5 to 7, wherein light sources (210) in the plurality of light sources (210) are arranged along concentric rings (214).

9. The device (2) according to any one of claims 5 to 8, the light emitting module (21) comprises groups of at least one light source (210) the controller (22) is configured to modulate an intensity of each group in a synchronized manner compared to one another, so that a position of the region irradiated by the light emitting module (21) moves across the fundus with a velocity under 10 degrees per second.

10. The device (2) according to claim 9, wherein the position of the region irradiated by the light emitting module (21) moves with a velocity comprised between 1 degree per second and 3 degrees per second.

11. The device (2) according to any one of claims 3 to 10, wherein a center of the dynamic irradiation pattern (12) is configured to irradiate a central region of the fundus (11) and wherein a fixation pattern (214) is placed at a center of the dynamic irradiation pattern (12).

12. The device (2) according to any one of claims 1 to 11 , wherein the device (2) further comprises a processor (24) and an image capture device (23), the processor (24) being configured to process images acquired by the image capture device (23) and being functionally connected to the controller (22), the controller (22) being configured to control the light emitting device (2) according to an information provided by the processor (24).

13. The device (2) according to any one of claims 1 to 12, wherein the light emitting module (21) comprises an OLED screen and / or a LED and / or a laser and / or a diffused light source (210) combined with physical filters and masks and / or a light source (210) combined with a screen with fluorescent dyes.

14. Method for myopia control using red light irradiation, said method comprisingthe following step:- Irradiating a region of the fundus (11) of an eye (10) of a subject (1) during an irradiation period (Tirr) with light having a first wavelength comprised between 600 nanometers and 680 nanometers, said region being irradiated according to a dynamic irradiation pattern (12) emitted by a light emitting module (21) comprising at least one light source (210) an intensity of said at least one light source (210) being modulated.

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