Apparatus and method for obtaining an erg signal

Abstract

An apparatus for obtaining a retinal ERG signal from a target region of a retina, the apparatus comprising equipment for obtaining an electrical response signal from the target region and at least one light source configured to provide at least a stimulus light beam and a light-adapting background light beam, the stimulus light beam being configured to illuminate the target region to evoke the ERG signal, the light-adapting background light beam being configured to illuminate the retina at least in a region outside the target region for light-adapting the region outside the target region and suppressing the ERG signal transmitted from the region outside the target region.

Description

Technical Field

[0001] This invention generally relates to electroretinography (ERG). More specifically, this invention relates to obtaining enhanced focused ERG signals. Background Technology

[0002] Electroretinography (ERG) is a method of recording the electrical signals (electrical responses) of the retina when it is exposed to stimuli (such as flashes of light). This can be useful in various situations, such as diagnosing retinal diseases.

[0003] In existing technologies, devices that obtain focused ERG signals often produce combined signals, including response signals from the target region of the retina and interference response signals from regions outside the target region. The interference response signals are generated due to the scattering of stimulus light into the vicinity of the retina outside the target region.

[0004] Known devices for obtaining ERG signals have drawbacks, namely that the obtained ERG signals cannot adequately indicate the signal state of retinal neurons in the target region.

[0005] ERG can be used alone, and it has also been found that, due to the temperature dependence of retinal electrical signals, ERG signals obtained during retinal heating (such as photothermal retinal therapy) can be used to determine the temperature of the retina. Therefore, ERG signals obtained during retinal heating can indicate the temperature (or at least the temperature difference) occurring on the retina due to heating (such as laser heating). Furthermore, the temperature determination related to heating can be used, for example, to control retinal heating so that the retinal temperature is maintained at a desired level.

[0006] Because ERG signals cannot adequately indicate local retinal signals and photoadaptation caused by therapeutic lasers, the retinal temperature determined from the signals may be inaccurate.

[0007] In retinal heating applications, laser dots can be used to heat retinal tissue. Known laser dots used in the prior art include top-cap distributions, where the irradiance of the laser dot is approximately constant within a circular target area and drops to zero outside the circular target area. Summary of the Invention

[0008] The object of this invention is to at least alleviate some of the problems in the prior art. According to one aspect of the invention, an apparatus for obtaining retinal ERG signals from a target region of the retina is provided. The apparatus includes: equipment for obtaining an electroreactivity signal from the target region and at least one light source configured to provide at least one stimulation beam, configured to illuminate the target region to induce an ERG signal; and a light-adapting background beam configured to illuminate the retina in at least a region outside the target region, for light-adapting the region outside the target region and suppressing the resulting ERG signal.

[0009] According to one embodiment, a method for obtaining an ERG signal is also provided.

[0010] In another aspect, an apparatus is provided for heating at least a target area of ​​the retina, the apparatus comprising at least a heating light source for providing a heating beam to heat at least the target area, wherein the heating beam includes an irradiance profile including a lower irradiance region, wherein the brightness of the heated point is lower than that of the higher irradiance region.

[0011] In view of the utility of the embodiments of the present invention, an apparatus and method for obtaining ERG signals are provided, wherein the obtained ERG signals can be enhanced in the sense that the obtained signals can more accurately indicate the response of the stimulus / target tissue (rather than the surrounding tissue).

[0012] This invention can enhance the accuracy of the obtained ERG signal when the ERG method is used alone or when ERG is used during retinal heating, wherein the obtained ERG signal can be used more effectively to determine retinal temperature.

[0013] The inventors have discovered that in the prior art, devices attempting to record ERG signals during retinal heating produce erroneous results due to the source of the acquired ERG signals. The acquired signal not only indicates the ERG signal of the treated / target / heated retinal region, but also includes ERG signals generated in the periretinal region due to the scattering of stimulation light into areas near the retina outside the target region. Therefore, any further analysis based on this signal (such as determining the retinal temperature) is inaccurate.

[0014] The inventors also realized that in previous methods utilizing retinal heating, insufficient illumination of the fundus caused the heating laser to affect the obtained ERG signal through optical adaptation and retinal temperature rise, and these effects could not be distinguished from each other. Similarly, any further analysis based on the ERG signal would be inaccurate.

[0015] In embodiments of the invention, the obtained ERG signal can more accurately indicate the response of the target retinal region to the stimulation of the stimulus beam because the light-adapted background beam can suppress the ERG signal in retinal regions outside the target region by illuminating (and thus light-adapting) at least one retinal region outside the target region, reducing the ERG response caused by the scattered stimulus light. Furthermore, any further analysis involving the ERG signal may therefore be more accurate.

[0016] In one embodiment of the invention, the central background beam is bright enough that the photoadaptation effect of the heated laser is substantially negligible. Therefore, the obtained signal is only affected by the temperature increase caused by the heated laser, and not by changes in the photoadaptation state. In one embodiment, the brightness of the central background beam exceeds 50 lux, and the brightness in the fundus preferably exceeds 100 lux, so that the heated beam does not cause significant photoadaptation in the target area.

[0017] During retinal heating, the fundus is typically imaged so that, for example, the physician performing the retinal heating can monitor the eye and / or appropriately focus the heating, typically on a small portion of the retina. Embodiments of the present invention provide an optically adapted background beam that can provide an enhanced ERG signal; however, the inventors have noted that the optically adapted background beam can interfere with fundus imaging through backreflection artifacts. Therefore, one embodiment of the present invention provides an optically adapted background beam that essentially blocks fundus imaging, for example, by using an optical notch filter to block the imaging of the optically adapted background beam. Here, fundus imaging can be performed efficiently without interference from the optically adapted background beam because interfering reflections are blocked outside the imaging system; these interfering reflections are reflections of the optically adapted background beam, such as reflections scattered from the retinal lens surface, from the surface of the eye, and / or from inside the eye.

[0018] In one implementation, the light-adapted background beam includes polarized light, and a polarizer is used to block the light-adapted background beam for fundus imaging.

[0019] In another implementation, the light-adaptive background beam is modulated with an on / off waveform, and the camera sensor of the imaging module is synchronized to be exposed essentially only when the light-adaptive background beam is off, in order to prevent the light-adaptive background beam from reaching the imaging system.

[0020] In one embodiment involving retinal heating, the stimulation beam may be equal to or smaller in size than the heating beam used to heat the region, which, when directed to a final location associated with the retina, at least corresponds to the target region. Optionally, the stimulation beam may have a beam area such that, when directed to the final location associated with the retina, the stimulation beam area is approximately 50% to 90% of the heating beam area, preferably approximately 70% to 80% (e.g., diameter and concentric with the heating beam / point). The temperature rise in retinal tissue induced by the heating beam is likely to be highest at the center of the heating beam region and decrease towards the edges of the heating beam. It is advantageous to induce an ERG signal in the retina with the stimulation beam, particularly at the center of the heating beam (and therefore at the center of the target region), such that the ERG signal indicates that the temperature of the target region follows the highest temperature rise.

[0021] In one embodiment, the stimulation beam can be modulated using pulsed flashes. In another embodiment, the stimulation can be a square wave. In a third embodiment, the stimulation beam can be modulated using white noise.

[0022] The light-adaptive background beam can be adapted to illuminate an area on the eye, from substantially at the periphery of the target area or from near the periphery of the target area to or beyond the ocular equator. A light-adaptive background beam that substantially illuminates the retinal area reaching from substantially at the periphery of the target area or from near the periphery of the target area (defined by the periphery of the heated area) to or beyond the ocular equator can more effectively suppress / prevent ERG signals that may originate from areas of the eye outside the target area.

[0023] The light-adaptive background beam may include a lower illuminance region or a no-illuminance region corresponding to the stimulus beam, such that when the stimulus beam and the light-adaptive background beam are directed relative to the eye to their final position, the lower illuminance region or no-illuminance region substantially coincides with the stimulus beam. Therefore, the lower illuminance region or no-illuminance region substantially corresponds to the target region. The lower illuminance region may, for example, include an illuminance at least 50% lower than that of the light-adaptive background beam in other regions, and this illuminance may also preferably be at least 70% lower, or more preferably at least 90% lower. This "dark spot" at, for example, the center of the light-adaptive background beam allows the target region to be at a lower light-adaptive level relative to the peripheral regions, and therefore, since the target region is more sensitive to light than the peripheral regions, light scattering artifacts in the obtained ERG signal can be reduced.

[0024] In another further aspect, the invention also relates to an apparatus for heating a heating region or target region of the retina, the apparatus comprising a heating light source configured to provide a heating beam including an irradiance profile of a heating point, the heating point including a lower irradiance region substantially at the center of the heating point, wherein the irradiance is lower than that of a higher irradiance region at the edge of the heating point.

[0025] Preferably, a region of lower irradiance (e.g., no irradiance) is provided at the center of the heating beam, such that the heating beam (or at least the portion of the heating beam with higher irradiance than the center point) is annular.

[0026] The inventors believe that the top-hat distribution of laser dots in the prior art may be disadvantageous, at least in the context of long-pulse retinal laser treatment, because the temperature rise in the retina is highest at the center of the heated beam and decreases towards the edges of the target area. It has been recognized that, in cases where consistent treatment is required within the target area, i.e., consistent elevation of the retinal tissue, a more uniform heat distribution provided by the heated beam may be advantageous.

[0027] The lower illuminance region may, for example, comprise an irradiance of the heating beam that is at least 50% lower than that of other regions, and preferably at least 70% lower, or more preferably at least 90% lower. With this type of heating beam, the temperature distribution of the heating beam may be more uniform, and / or a lower temperature rise may be provided at the center of the heating region. The annular heating point can also be used in devices that obtain ERG signals during retinal heating, and in devices that also provide a light-adapted background beam, as described elsewhere in this application. However, the annular heating point can be used in any retinal heating application.

[0028] Irradiance can increase substantially linearly or parabolically, for example, between a first, lower irradiance value at the center of the heating point and a second, higher irradiance value at the edge of the heating point.

[0029] The irradiance at the edge of the heating point can be 5% to 100% higher than that at the center of the heating point, and advantageously 20-50% higher.

[0030] The area of ​​lower irradiance can be defined by a circle with a diameter of 0.1 to 1 mm and can be provided essentially at the center of the heating point.

[0031] In some implementations, the irradiance profile can be selected based on the temperature rise of the retinal tissue in a defined target region, optionally by determining the difference between the temperature rise at the edge of the target region and the temperature rise at the center of the target region.

[0032] In embodiments involving retinal heating and ERG stimulation, heating of the target region refers to heating at least the target region illuminated by the stimulation beam. Heating may also extend to, for example, a region larger than the target region illuminated by the stimulation beam.

[0033] The exemplary embodiments presented herein should not be construed as limiting the applicability of the appended claims. The verb "comprising" is used herein as an open-ended limitation, not excluding the presence of features not mentioned. Unless otherwise expressly stated, the features recited in the appended claims can be freely combined with each other.

[0034] Novel features considered characteristic of the invention are specifically set forth in the appended claims. However, the invention itself, both in its structure and its method of operation, as well as its additional objects and advantages, will be best understood from the following detailed description of specific embodiments when read in conjunction with the accompanying drawings.

[0035] Those skilled in the art will understand that the various considerations for implementing the apparatus presented can be flexibly applied to the implementation of the method, and vice versa. Attached Figure Description

[0036] Next, exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings, wherein:

[0037] Figure 1 An exemplary apparatus according to one embodiment of the present invention is shown.

[0038] Figure 2 The diagram illustrates the temperature rise on the retina using a heated beam with a conventionally shaped heating point and a ring-shaped heating point. The center of the heating point has two different sized areas of lower irradiation or no irradiation.

[0039] Figure 3 An exemplary device for retinal heating according to one embodiment of the present invention is schematically depicted. Detailed Implementation

[0040] Figure 1 An apparatus for obtaining retinal ERG signals is shown according to one embodiment of the present invention. Figure 1 The device shown is connected to a retinal heating system and an imaging system. The device includes at least one light source. The at least one light source is configured to provide at least one stimulation beam to illuminate a target area of ​​the retina to stimulate the target area and induce a focused ERG signal. The device also includes at least one light source configured to provide a light-adapted background beam to illuminate at least an area of ​​the retina outside the target area.

[0041] In a preferred embodiment of the invention, a central background beam may optionally be provided for illuminating a target area at least on the retina. The provided beam can be generated using a separate light source, and for example, in one embodiment, the light-adapted background beam and the central background beam may be provided by the same light source. This light source is preferably individually controllable.

[0042] exist Figure 1 In this embodiment, the stimulation beam is provided by a stimulation light source LED3. The stimulation beam is used to illuminate a target area of ​​at least the retina, where the target area is the region from which ERG signals are to be obtained, and optionally, the area to be heated / to be heated during retinal heating. In the absence of retinal heating, the target area stimulated / irradiated by the stimulation beam can directly refer to the area irradiated by the stimulation beam; in embodiments involving retinal heating, the target area can refer to the heated area, in which case the area irradiated by the stimulation beam may not correspond to the entire target area. The stimulation beam is used to excite / induce ERG signals in the target area. The stimulation beam light source LED3 can be a light-emitting diode (LED) light source configured to provide a stimulation beam with a wavelength of 500 to 600 nanometers, for example, about 555 nanometers. Red and green cone cells have similar sensitivity at a wavelength of 555 nanometers; therefore, a stimulation beam exhibiting a wavelength close to this can similarly stimulate both cell types. The stimulation beam can include white light, which can stimulate all retinal cone cells equally.

[0043] In one embodiment of retinal heating, the stimulation beam may be the same size as or smaller than the heating beam used to heat at least the target area. For example, the stimulation beam may have 50% to 90% of the beam / spot diameter, such as approximately 75% of the treatment beam diameter.

[0044] The stimulation light source LED3 can be configured to provide a modulated stimulation beam. Therefore, the stimulation beam may not be provided as a continuous beam, but may include a sequence, such as pulsed flashes, pseudo-random waveforms, or square waves. Modulation can be implemented at frequencies, for example, between 4 and 40 Hz, advantageously between 10 and 25 Hz.

[0045] Figure 1 An adaptive background beam provided by an adaptive background light source LED1 is shown. This adaptive background beam is configured to illuminate at least a region of the retina outside the target region, and is configured to suppress or minimize ERG signals from outside the target region by illuminating this region of the retina. The adaptive background beam is advantageous in embodiments providing retinal heating, and in embodiments configured to obtain ERG signals without retinal heating.

[0046] The light-adaptive background beam may include a lower illumination region or a no-illumination region corresponding to the stimulus beam, such that when the stimulus beam and the light-adaptive background beam are directed relative to the eye to their final position, the lower illumination region or no-illumination region substantially coincides with the stimulus beam. The target area (the area illuminated by the stimulus beam and / or the area heated by the heating beam) may not be illuminated by the light-adaptive background beam (or at least less illuminated than the surrounding area). The no-illumination region may, for example, correspond to a circular area with a diameter of 3 mm (e.g., in a system where the stimulus beam diameter is 3 mm).

[0047] The light-adapting background light source LED1 can be an LED light source. The light-adapting background light source LED1 may also include a bandpass filter. The bandwidth of the light-adapting background beam can be reduced to, for example, 10 nanometers.

[0048] Figure 1 The illustrated device is connected to a fundus imaging system IS (which may also be implemented as part of the device in some embodiments). For example, the fundus imaging system IS may be a biological microscope, a fundus camera, or a scanning laser fundusoscope. The fundus imaging system may include a first imaging module IM1 and a second imaging module IM2, as well as one or more filters, such as a second filter F2 and a third filter F3.

[0049] Back reflections from surfaces along the beam path, such as the retinal lens and the surface of the eyeball, can cause significant imaging artifacts when reflected onto the imaging optics. Therefore, it may be advantageous to configure the device so that back reflections are essentially eliminated or at least reduced in retinal imaging. This can be achieved in many ways, where the back reflection beam is essentially blocked from reaching the imaging system.

[0050] In one embodiment, the light-adapted background beam can be blocked by an optical filter from passing through the fundus imaging system for imaging, thereby blocking the light-adapted background beam from performing fundus imaging. This optical filter can be an optical notch filter (band-stop filter), and can be... Figure 1 The second filter F2 in the process.

[0051] In one embodiment, an optically adapted background beam can be generated using polarized light, and fundus imaging can be performed by using a polarizer that blocks the optically adapted background beam for imaging. This optical polarizer can be... Figure 1 The second filter F2 in the process.

[0052] In a further implementation, back reflections in imaging can be eliminated by modulating the light-adapter background beam with a fast on / off waveform and synchronizing the imaging module camera exposure so that the camera sensor is exposed only when the light-adapter background beam is in the off position.

[0053] exist Figure 1 In the device, a central background beam is provided by a central background light source LED 2. The central background beam is configured to illuminate at least the target area of ​​the retina and maintain the light adaptation level of the target area. The central background beam may be concentric with the target area and may be limited to illuminating essentially only the target area. The central background light source LED 2 may be an LED light source. The central background beam may include white light and / or have a brightness greater than 100 lux in the fundus.

[0054] In other embodiments, the central background beam may be provided by the same light source used to provide the light-adaptive background beam, or the central background beam may be provided by the same light source used to provide the stimulation beam. For example, the stimulation light source LED3 may be configured to provide a stimulation beam in which the beam maintains a low intensity between successive stimulation light pulses to provide a central background beam between stimulation pulses.

[0055] When used in conjunction with retinal heating, the brightness of the central background beam can be configured to decrease as the heating laser or other heating equipment is turned on, in order to maintain stable illumination in the target area.

[0056] In embodiments of the invention, where infrared imaging is used for fundus imaging, a central background beam may not be required.

[0057] The device may also include equipment for acquiring an ERG signal, i.e., equipment for acquiring a response signal of a target region to stimulation provided by a stimulation beam. The ERG signal can be an electrical response that can be recorded / collected or acquired by one or more ERG electrodes. The electrodes may include one or more ocular electrodes and one or more reference electrodes. The ERG signal can be acquired as a voltage that varies over time between at least two electrodes.

[0058] The device may include or be connected to a fundus lens L6. The fundus lens L6 can guide the provided light beam to the fundus. For example, the fundus lens L6 may be an inverted fundus lens with a field of view greater than 120 degrees.

[0059] In one implementation, the fundus lens can be integrated into the device, so there is no need to place the lens on the cornea.

[0060] In one embodiment, the device includes a fundus lens, and an ocular electrode may be integrated into the fundus lens.

[0061] The heating system that can be used with this device, or that may be part of this device, may include at least one heat source, such as a heating laser LF, configured to increase the temperature of the target region of the fundus. The heating light source LF may be configured to provide a heated beam directed to the target region.

[0062] The heating beam can include wavelengths in the near-infrared region. The wavelength of the light contained in the heating beam can be 700 to 1000 nanometers, and the heating beam can be provided by a fiber-coupled diode laser (LF).

[0063] In one embodiment, the heated beam has a uniform irradiance profile and a dot diameter of 1 to 6 millimeters in the fundus.

[0064] One embodiment of the invention also provides an apparatus for retinal heating, comprising a heating light source configured to provide a heating beam including a region of lower irradiance (e.g., no irradiance) at the center of the heating beam, such that the heating beam (or at least a portion of the heating beam having higher irradiance than the center point) is annular in shape. The annular heating point is advantageous for apparatuses that obtain ERG signals during retinal heating, but can also be used to provide improved retinal heating without providing ERG stimulation. The annular heating point will be used in conjunction with… Figure 2 The relevant parts will be discussed in more detail.

[0065] In one implementation, the heating beam may include or be associated with the aiming beam, the beam / spot size and irradiance profile of which are substantially equivalent to those of the heating beam. Optionally, when the heating beam is activated, the power of the aiming beam may be configured to be reduced to maintain substantially stable irradiance over the target area.

[0066] In addition, other heating systems or heating equipment can also be connected and used with devices related to retinal heating. For example, the heating system can be implemented using ultrasound.

[0067] Considering Figure 1 The functionality of the illustrated apparatus and other related components is described below, along with a use case scenario. The four beams discussed above can be directed onto the same channel and projected onto the conjugate plane CP1. Therefore, four optical channels may be involved, corresponding to the stimulation beam, the light-adapting background beam, the central background beam, and the heating beam. The heating beam can be guided onto the first mask M1 by the first lens L1. The light-adapting background beam can be guided onto the second mask M2 by the second lens L2. The central background beam can be guided onto the third mask M3 by the third lens L3. The stimulation beam can be guided onto the fourth mask M4 by the fourth lens L4.

[0068] The fundus lens L6 projects the light distribution at CP1 onto the fundus. The first imaging module IM1 is configured such that CP1 is projected onto a camera sensor, or the surgeon's eye can focus on CP1 through the eyepiece of a biological microscope. The light beam through the fifth lens L5 is directed to the eye by the first mirror M1. The first mirror M1 can be placed directly in front of the first optical module IM1 (e.g., a biological microscope), so that the left eye can see the fundus to the left of the first mirror M1, and the right eye can see the fundus to the right of the first mirror M1. The fifth lens L5 projects the images from masks M1, M2, M3, and M4 onto the conjugate plane CP1; that is, the light distribution emitted through the masks is imaged onto CP1. Beam distributors BS1, BS2, and BS3 combine the beams from the fiber output LF of the heated laser and the light sources LED1, LED2, and LED3.

[0069] exist Figure 1 In this design, masks M1, M2, M3, and M4 are apertures through which light rays are projected onto the conjugate plane CP1. The mask can also be a plastic mirror or a digital micromirror device, in which case light is reflected from the mask rather than passed through it. In some embodiments, the mask can be used to achieve light adaptation to any dark spots or low-irradiance or no-irradiance areas in the background beam and / or heated beam.

[0070] The first filter F1 can be used to narrow the spectrum of the light-adapted background beam provided by the light-adapted background light source LED1. The passband of F1 can be 10 nm. The second filter F2 can be an optical notch filter with a 25 nm stopband centered at 530 nm, which can be used to prevent the light-adapted background beam from entering the second imaging module IM2. The third filter F3 can be an infrared cut-off filter to prevent laser light from being introduced into the imaging module IM2. The second imaging module IM2 can include a beam splitter to split the imaging light into two channels, one for the camera system and the other for the eyepiece.

[0071] In some implementations involving retinal heating, it may be advantageous for a portion of the treatment area to be at a lower temperature relative to the peripheral region. This is often the case when it is desirable to provide lower heat to a specific area of ​​the retina, such as the fovea. In these implementations, the irradiance profile can be designed to produce a lower temperature rise at the center than at the periphery. This can be achieved by having a lower irradiance region at the location of the heating point, corresponding to the location of the target area of ​​the retina where less heat is to be provided. For example, the lower irradiance region could be a circular area with a diameter of 0.5 mm, where the irradiance at the center of the laser point on the fundus is essentially zero.

[0072] Figure 2This illustrates the temperature rise (in degrees Celsius) on the retina of a heated beam using a conventionally shaped top-cap heating point (solid line, with a diameter of 0 mm for dark spots or lower illumination areas) and a ring-shaped heating point (dashed line). The heating point has two lower illumination or no illumination areas of different sizes at its center. The temperature rise is shown as a function of distance from the center of the heating point.

[0073] Figure 2 The 2A spot diameter is 3.3 mm, and the annular spot has essentially no-irradiance areas (dark spots) with diameters of 0.5 mm and 1 mm. Figure 2 Figure 2B shows a heating point with a diameter of 4 mm, a heating point with an irradiance profile centered on a zero-irradiance region (sudden change in irradiance) with a diameter of 0.5 mm, and a heating point with an irradiance profile where the laser power linearly increases from a relative value of 0.7 to 1 as the point moves from its center towards its edge. When the distance from the center is greater than 2 mm, i.e., the point diameter is 4 mm, the irradiance drops to zero.

[0074] Figure 2 The results show that using a ring-shaped heating point results in a more uniform temperature rise over the heated retinal area. The ring shape avoids the high temperature peaks (as seen with a circular heating point) at the center of the heating point (or area). Then, using a heating point with one or more lower irradiation areas, the irradiance profile on the retina may be more uniform. Providing a more uniform heat distribution with heating points that include lower irradiation areas may facilitate delivering more even heat to different parts of the treatment area (i.e., the target area of ​​the retina). Figure 2 As shown in section 2B, as the irradiance gradually increases from the center to the edge of the heating point (e.g., linearly), the temperature rise in the tissue may be more uniform than with other annular heating points according to the invention. In some cases, a more uniform temperature distribution may be required, while in others, it may be advantageous to obtain a temperature distribution on the retina in which the temperature at the center of the heated area is lower than at the edge. This can be used, for example, when the heating treatment is concentrated in the fovea, to ensure that the entrance to the fovea is not damaged by excessively high temperatures.

[0075] In specific use cases, smaller circles of different sizes defining low-irradiance or no-irradiance regions can be used to obtain the desired temperature distribution. For example, the diameter of the smaller circle can be approximately 5% to 50% of the diameter of the heating point, preferably 10% to 20%. The low-irradiance region can, for example, be essentially defined by a circle with a diameter of 0.1 to 1 mm.

[0076] The change in irradiance can be considered to occur gradually, such that the irradiance gradient around a region can be considered as a smaller circle defining the annular shape. Advantageously, the irradiance can increase substantially linearly between a first, lower irradiance value at the center of the heating point and a second, higher irradiance value at the edge of the heating point.

[0077] Irradiance can increase linearly between a minimum or first value at the center and a higher (preferably the highest) second value at the periphery / edge. This produces a more uniform temperature distribution in the fundus compared to a uniform irradiance profile. Advantageously, irradiance can be configured to be 5% to 100% higher at the periphery than at the center, and more advantageously 20% to 50% higher at the periphery than at the center.

[0078] The diameter of the heating point can be selected according to the pathological condition being treated; for example, it could be 4 millimeters. The irradiance value of a 4-millimeter diameter heating (laser) point could be 1 to 10 watts per square centimeter at the center of the heating point.

[0079] Since the temperature rise in retinal tissue caused by heating (such as laser irradiation) can vary greatly among different patients, it may be beneficial to perform personalized heating laser power calibration for each patient, in which subtherapeutic heating irradiation is applied, the resulting temperature rise in the target area of ​​retinal tissue is determined (e.g., by ERG method), and the heating power during treatment is optimized to produce the desired temperature rise in retinal tissue based on the temperature rise and laser power used in the subtherapeutic heating irradiation.

[0080] For example, customized heating points can be achieved through optimization methods, making them brighter at the edges than at the center. In one implementation, the irradiance profile can be optimized using finite element method thermal modeling to determine the heat distribution of the heating points achieved by a given irradiance profile.

[0081] A set of different irradiance profiles can be tested, and an irradiance profile that provides the desired heat distribution in the target area can be selected. The lateral temperature distribution of the target / heated area is influenced by physiological parameters, such as choroidal perfusion rate. In a computational model with a range of naturally occurring physiological parameters, an irradiance profile can be selected to produce the optimal uniform temperature distribution.

[0082] Methods for providing a selected or desired irradiance profile may involve computer-implemented simulations or calculations, such as thermal modeling using the aforementioned finite element method, to determine an optimized or selected irradiance profile of the heated beam that meets predetermined criteria, such as providing a uniformity curve for selected heating points.

[0083] In one implementation, a calibration procedure can be used to determine the heating power for retinal heating at the treatment level, maintaining the shape of the irradiance profile unchanged between patients. However, in some implementations, the heating power and / or the shape of the irradiance profile can be optimized for the treated patient and retinal region based on a calibration protocol to optimize the irradiance profile of the heating point.

[0084] The calibration protocol may include determining the retinal temperature from two retinal regions, which may be the center of the target area and a ring covering the outer periphery of the target area. The increase in heating power between the center and the periphery can be determined based on the determined temperatures at the center of the treatment area and the edge of the ring-shaped treatment area.

[0085] In one exemplary embodiment, the desired irradiance profile can be achieved by illuminating the digital micromirror device with a uniform laser spot and projecting an image of the digital micromirror device onto the retina through a fundus lens. The irradiance profile can be encoded on the digital micromirror device by adjusting the relative time of each micromirror in its off and on states.

[0086] Figure 3 An exemplary device 300 for heating a target area of ​​the retina of an eye 302 is shown. The device 300 includes heating at least a light source LF for providing a heating beam to heat at least the target area, wherein the heating beam includes providing an irradiance profile of a heating point comprising a low-irradiance area.

[0087] The device 300 may also include a stimulation light source LED 3, configured to provide a stimulation beam. The stimulation beam can be used to illuminate an area from which at least an ERG signal is to be obtained, which may correspond to a target area that is heated / to be heated during retinal heating. The device may also include an optical element 304, which may correspond to the optical elements described elsewhere herein.

[0088] In one embodiment, the irradiance profile of the heating point can be, for example, derived from... Figure 1 The mask corresponding to M1 in the image is used for control, where M1 can be a graded neutral density filter that reflects the desired irradiance profile, or a digital micromirror device that reflects the desired irradiance profile.

[0089] The present invention has been described above with reference to the embodiments described above, and several advantages of the present invention have been demonstrated. It is clear that the present invention is not limited to these embodiments, but includes all possible embodiments within the spirit and scope of the inventive concept and the following patent claims.

[0090] Unless otherwise expressly stated, the features described in the dependent claims can be freely combined with each other.

Claims

1. An apparatus for obtaining a retinal ERG signal from a target region of the retina, the apparatus comprising equipment for obtaining an electroreactivity signal from the target region and a heating system for at least heating the target region, wherein, The heating system includes a heating light source for providing a heating beam to at least heat the target area, and the device further includes at least one light source configured to provide... - A stimulation beam, configured to illuminate the target region to induce ERG signals. - An optically adapted background beam, configured to illuminate the retina at least in areas outside the target area, for optically adapting to areas outside the target area and suppressing ERG signals transmitted from areas outside the target area, and - A central background beam is configured to illuminate at least the target area of ​​the retina to maintain the light adaptation level of the target area.

2. The apparatus according to claim 1, wherein, The light-adapting background beam is adapted to illuminate a region on the fundus from or near the periphery of the target area to or beyond the ocular equator.

3. The apparatus according to any one of the preceding claims, wherein, To prevent the light-adaptive background beam from reaching the fundus imaging system.

4. The apparatus according to claim 3, wherein, An optical notch filter is used to block the light-adapted background beam for fundus imaging.

5. The apparatus according to claim 3, wherein, The light-adapted background beam includes polarized light, and a polarizer is used to block the light-adapted background beam for fundus imaging.

6. The apparatus according to claim 3, wherein, The light-adaptive background beam is modulated with an on / off waveform, and the camera sensor of the imaging module is synchronized to be exposed only when the light-adaptive background beam is off.

7. The apparatus according to claim 1, wherein, The light-adaptive background beam includes a lower illuminance region or a no-illuminance region corresponding to the stimulus beam, such that when the stimulus beam and the light-adaptive background beam are guided to their final positions relative to the eye, the lower illuminance region or the no-illuminance region coincides with the stimulus beam, wherein the lower illuminance region includes at least 50% lower irradiance than the light-adaptive background beam in other regions.

8. The apparatus according to claim 1, wherein, The heating beam has a circular, uniform irradiance profile and a diameter of 1 to 6 millimeters at the fundus.

9. The apparatus according to claim 1, wherein, The size of the stimulation beam is equal to or smaller than that of the heating beam used to heat at least the target area.

10. The apparatus according to claim 1, wherein, The heating source is configured to provide an aiming beam with a beam size and irradiance profile equal to that of the heating beam.

11. The apparatus according to claim 10, wherein, The power of the aiming beam is configured to decrease when the heating beam is turned on, in order to maintain stable illumination in the target area.

12. The apparatus according to claim 1, wherein, The brightness of the central background beam is configured to decrease as the heating system is turned on in order to maintain a stable illuminance in the target area.

13. The apparatus according to claim 1, wherein, The brightness of the central background beam exceeds 50 lux.

14. The apparatus according to claim 13, wherein, The brightness of the central background beam exceeds 100 lux.

15. A method for obtaining an ERG signal, the method comprising at least: Direct the stimulation beam to the target area of ​​the retina. Heat the target area. The light-adapted background beam is directed at least to a retinal region outside the target region to suppress ERG signals transmitted from the retinal region outside the target region by light-adapting the retina at least in a region outside the target region. The central background beam is directed at least to the target area to maintain the light adaptation level of the target area, and At least one signal related to the ERG signal of the retina is obtained.

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