EP1954228A2

EP1954228A2 - Device and method for photocoagulation of the retina

Info

Publication number: EP1954228A2
Application number: EP06791741A
Authority: EP
Inventors: Martin Wiechmann; Manfred Dick; Diego Zimare; Regina SCHÜTT
Original assignee: Carl Zeiss Meditec AG
Current assignee: Carl Zeiss Meditec AG
Priority date: 2005-11-23
Filing date: 2006-08-30
Publication date: 2008-08-13
Also published as: DE102005055885A1; WO2007059814A3; DE102005055885B4; US20140288537A1; JP4938787B2; US20080300581A1; WO2007059814A2; JP2009516552A

Abstract

The invention relates to a device and a method for photocoagulation of the retina, comprising a radiation source (10) and an optical application system (20), wherein the optical application system has a display unit for displaying areas of the retina (5) with sub-threshold coagulation.

Description

Device and method for photocoagulation of the retina

The invention relates to a device and a method for photocoagulation of the retina.

Light coagulation was first used in the late 1940s by the focused light of an axial high pressure lamp to treat various diseases of the retina, such as diabetic retinopathy. By absorption of the laser beam, especially in the pigment epithelium, a retinal layer bearing a dark dye, the retina is heated and coagulated. This focuses the metabolism on the still healthy areas of the retina. In addition, biochemical cofactors are stimulated. The course of the disease is significantly slowed down or stopped.

Mostly lasers are used today as a light source. Previous systems for photocoagulation of the retina are based on the visual control of so-called coagulation herds. The radiation dose of the laser is set so high that a visually recognizable discoloration of the retina arises. In the process, the receptors and nerve fibers in the coagulation focus are destroyed. However, a smaller dose is already sufficient for the therapeutic effect. Residual vision could be maintained at lower doses - attempts to provide systems that provide feedback on the dose introduced to control so-called sub-threshold coagulation have not yet been translated into stable solutions. Subliminally coagulated areas of the retina can not be recognized ophthalmoscopically. A visualization subliminally coagulating Retinal areas is only possible with expensive procedures, such as fluorescein angiography.

The object of the present invention is therefore to provide a device and a method for photocoagulating the retina, which informs about subliminally coagulated regions of the retina and their position.

The object is achieved by a device for photocoagulation of the retina comprising a radiation source and an optical application system, wherein the optical application system has a display device for displaying subliminally coagulated regions of the retina. In particular, lasers may be considered as the radiation source. Argon lasers, diode lasers, diode-pumped solid-state lasers, diode-pumped semiconductor lasers, Yag lasers, excimer lasers, etc. are preferably used. The lasers can be pulsed or used as CW lasers. In addition, other light sources are conceivable, such as, for example, focused light of a xenon lamp, light-emitting diodes (LEDs), superluminescent diodes (SLDs), etc.

As an optical application system, any device that can direct or direct radiation of the radiation source is suitable. Such an optical application system may preferably be an optical system which may comprise diaphragms with corresponding profiles. Particularly preferably, microstructured coatings can also be included on a glass substrate of the optical application system. The optical application system can also comprise optical waveguides, controllable elements such as, for example, small transmissive LCD panels, micromirror elements, diaphragms, deflecting mirrors, magnification and / or reduction optics, optics with free-form surfaces, diffractive optics, GRIN optics (graphics). serves / index), preferably at the end of the Lichtleitphase (similar to an adapter), active elements such as a Digital Mirror Device (DMD), etc. By the optical application system, the beam of the radiation source can be aligned and imaged in a predefined spatially distributed intensity profile.

Particularly preferably, the device also comprises a display device. With this display device, the result of the photocoagulation can be checked - particularly preferably optically checked. It is therefore possible by means of this display device that the result of the photocoagulation is checked optically - by visual inspection or by the provision of markings. For example, a permanent, visible alteration of the retina in the areas in which it has been treated can be provided as a presentation device. This can be achieved, for example, by at least partially producing visual coagulation in the treated areas. In this case, the organic substances present in the irradiated areas are changed in such a way that these areas can be recognized ophthalmoscopically. In particular, an insertion of markings into an ophthalmoscope, preferably a projection on the retina, and particularly preferably a display on a screen, is used as the display device.

Subliminally coagulated areas are areas in which the intensity of the laser is sufficient to provide a visual coagulation-like therapeutic effect in the pigment epithelium, but not to make these areas ophthalmoscopically identifiable. It can therefore no longer be recognized ophthalmoscopically after treatment, which areas have been treated. The retina is in in which subliminal coagulation is present, partially functional.

Preferably, the presentation device has a beam modification device, by way of which a beam of the radiation source can be set in a predefined, spatially distributed intensity profile over the projected area of the beam on the retinae plane.

As a result, the homogeneous coagulation spot, which is usually large in the prior art, receives a spatially distributed intensity profile. Only in one or a few places does the intensity suffice for visual coagulation. In the remaining area, coagulation remains subliminal, preferably with a fixed relationship to the visually recognizable area. The subliminal coagulation is not visible ophthalmoscopically, the receptors and nerve fibers are not or only partially destroyed. Only at this or a few places where there is visual coagulation, the receptors and nerve fibers are completely destroyed. These locations are for dose control.

The retinal photocoagulation device according to the present invention particularly preferably comprises a beam modification device. Such a beam modification device is used to set the beam of the radiation source in a predefined spatially distributed intensity profile over the projected area of the beam on the retina plane. Such a beam modification device may comprise the above-described optical elements.

The beam of the radiation source is, for example, a light beam or laser beam emerging from the radiation source is aligned by the optical application system and undergoes the necessary modifications by the beam modification device, through which the desired intensity profile can then be imaged.

At the retina level on which the beam which has passed through the optical application system or the beam modification device is supposed to act, a predefined spatially distributed intensity profile is then imaged. This spatially distributed intensity profile is defined over the projected area of the beam on the retinal level. In this way, a beam is applied not only uniformly largely homogeneous to the retina, but has a distribution of intensity. Such a distribution can either be present directly or can be formed dynamically over the irradiation time.

Preferably, the spatially distributed intensity profile is adjustable so that visual coagulation can be generated on the retinal level at least in one area.

The spatially distributed intensity profile produces differently strong coagulations in the retina. These are preferably only partially ophthalmoscopically recognizable. That is, there is partly a subliminal and partly a visual coagulation. The areas which are recognizable ophthalmoscopically ideally identify the areas which are not recognizable ophthalmoscopically. This is achieved, for example, in that the visually coagulated areas form a circular ring in which the subliminally coagulated areas are located. Preferably, the intensity profile has two different maximum maxima. If the area of the retina which is subjected to the highest maximum visibly coagulates, this is preferably Signal to the surgeon that the area of the retina is sufficiently coagulated. When the area to which the second highest maximum is applied coagulates, this is preferably a signal for the surgeon to stop irradiation to the retina as soon as possible. Preferably, the intensity distribution is adjustable. Particularly preferably, the ratio of the different intensities of the intensity profile is mutually variable. Particularly preferably, the ratio of the intensities of the beam, which are to cause a visual or subliminal coagulation, adjustable. As a result, the intensity profile can be adapted to different retinas in such a way that during an operation the areas which are intended to coagulate subliminally are irradiated with an optimal intensity. The fact that the intensity of the beam, which is to cause a visual coagulation, is independently adjustable, the irradiation duration, which will be observed by the surgeon, optimally adjusted. The subliminal coagulation can be so safely reproduced.

Visual coagulation can be recognized ophthalmoscopically. In the areas of the retina where there is visual coagulation, the receptors and nerve fibers are destroyed. A therapeutic effect is achieved. The surgeon can ophthalmoscopically recognize without further aids, which areas have been treated. However, the functioning of the retina is destroyed in visually coagulated areas.

In a preferred exemplary embodiment of the present invention, the intensity profile comprises one or more defined maxima which, in the sum, have an area of less than 20%, preferably less than 10%, particularly preferably less than 20%. less than 5% of the area covered by the projected area of the beam at the retinal level.

Particularly preferably, the intensity profile comprises maxima defined with it which have a higher intensity than the remaining area covered by the beam of the radiation source. The area occupied by the maxima with respect to the total irradiated area through the beam is less than 20%, preferably less than 10%, and with particular preference less than 5%. In this way, only a small portion of the irradiated retina is injured to provide optical evidence of coagulation, while the remainder of the area is only subliminally coagulated and thus still retains certain visual capabilities. By restricting the areas irradiated with the maxima, the proportion of the retina which has not been completely destroyed by the coagulation within the irradiated area can thus be predetermined. If several maxima are included in the intensity profile, the area is formed by the sum of the corresponding maxima.

By choosing more than one maximum, the center of the beam area of the specific corner points of the irradiated area, which is directed onto the retina, can preferably be marked - in this way a visual examination of the already irradiated area of the retina is possible. Thus, for example, four maxima can be displayed at the same distance on the outer edge of the irradiation surface designed as a circular surface, which then visualize the irradiation in this special area.

In a further preferred embodiment of the present invention, the intensity of the at least one ximums in a fixed ratio to the intensity of the remaining range of the intensity profile adjustable.

As a result of this largely fixed ratio to the intensity of the maximum to the remaining region of the intensity profile, a defined relationship between the degree of coagulation achieved between the regions irradiated with maxima and the remaining region is preferably predefined. In this way, it is possible to apply a uniform predetermined dose of radiation to the retina, which causes subliminal coagulation. The now occurring visual coagulation points, which are generated by the maxima, thus serve to prove that a predetermined dose has acted evenly on the rest of the irradiated area.

In a further preferred embodiment of the present invention, the intensity of the maxima for visually visible coagulation is sufficient, while the intensity of the residual range of the intensity profile is less than 80%, preferably less than 60%, particularly preferably less than 50% of the intensity of the maxima.

The intensity of the maxima is preferably selected so that they are sufficient for visual control of the coagulation, while the intensity of the remaining region of the intensity profile is irradiated less intensively. As a result of this difference in the irradiation intensity, an irradiation can be visually checked or detected, with a fixed relationship with regard to the irradiation intensity being valid for the region outside the maximum. In this way, in the case of irradiation with a preselected ratio between the maximum and the rest, it can be assumed that when the optical coagulation has been reached, the remaining region has been irradiated with a special (optically not directly verifiable) dose is. This ratio can also be adapted individually to the circumstances of the particular patient, so that in one patient a different relationship is taken than is required in another patient. This ratio can be determined in a preliminary study as a test. This is particularly preferably done in a calibration mode before the actual treatment. The ratios thus obtained between the maximum, on the one hand, and the dose for irradiating the remaining surface, on the other hand, is then preferably maintained in a patient-specific manner. Such a calibration is particularly preferably carried out in a retinal area, which is not particularly decisive for the actual vision.

In a further preferred embodiment of the present invention, different maxima have mutually different predefined intensities.

The formation of different maxima with different predefined irradiation intensities makes it possible to adapt the irradiation even more precisely. Thus, by the choice of, for example, three maxima, a treatment can be oriented such that the radiation is set after the visual appearance of two maxima - the occurrence of a maximum is thus an indication for the surgeon that the dose can still be increased, while the The presence of three maxima is the sign for the surgeon to end the treatment at the latest. By choosing corresponding gradations between the maxima, an additional optical aid for the progress of the irradiation of the corresponding area can thus be given. In a further preferred embodiment of the present invention, the intensity profile can be generated statically or dynamically.

The generation of an intensity profile can be done either statically or dynamically. A static realization of the intensity profile can be effected, for example, by means of corresponding optics, lens systems or free-form surfaces, via which the intensity of the beam is kept constant over the entire time of the treatment. It can also be a series of very short pulses, which are shaped by appropriate optics in their intensity profile.

Likewise, it is conceivable to generate the intensity profile dynamically. A dynamic generation of an intensity profile can take place, for example, by a temporal course of the intensity of the beam, so that an increased dosage and thus a corresponding profile can be applied by increasing the intensity in specific areas of the area projected onto the retina by the beam. For example, it is also possible to change the intensity profile of an irradiation over time by means of scanners or diaphragms, diffractive optics or digital mirror devices, so that a higher intensity profile is applied only at specific predefined areas than in the other areas.

In a further preferred embodiment of the present invention, the beam modification device comprises a diaphragm with a defined profile.

Through an aperture with a defined profile can be achieved by switching on the aperture or by partial absorption of the Beam within the aperture a corresponding intensity profile can be specified. In this case, microstructured coatings on, for example, a glass substrate are particularly preferred. By means of such coatings, it is possible to generate specific intensity profiles by absorption of the beam or masking of partial beams.

In a further preferred embodiment of the present invention, the maxima are adjustable on a concentric ring around the center of the projected area of the beam on the retina plane.

Due to the spatial configuration of the maxima on the projected area, geometrically easily detectable figures can be represented, which not only visualize the achievement of optical coagulation during optical inspection, but at the same time still mark the area in which the non-visible irradiation of the remaining area took place Has. It is thus possible, for example, to represent by circular segments or a full circle the area in which coagulation has taken place. Likewise, it is possible by means of different maxima on a circle pointwise to mark the area that has been irradiated in total. For example, by marking three maxima on a circumference can thus be already reliably specify in which (residual) area irradiation has taken place.

Particularly preferably, a concentric ring is chosen around the center of the irradiation surface. In addition, it is also possible to realize wedge-shaped figures.

In a further preferred exemplary embodiment of the present invention, the maxima can be generated temporally variable in a calibration mode. Particularly preferably, by varying the intensity of the irradiation in a calibration mode before the actual treatment, it can be recognized at which power density the coagulation threshold is exceeded. The subsequent coagulations for the treatment of the other retina are then carried out in the subliminal area with a homogeneous spot or irradiated area. Thus, only in calibration mode, for example, a wedge-shaped intensity attenuation is pivoted into the beam path. This can preferably be realized as a gray wedge, a dielectric coating, a micro-optically diffractive or refractive element or else with the aid of active elements such as digital mirror devices (DMD), etc. This calibration step can preferably be carried out repeatedly at different points in the device according to the invention. Particularly preferably, the calibration step is always carried out at the beginning of a treatment and, if necessary, repeated at intervals, for example, in the case of significantly differently absorbing retinal realms. Most preferably, the calibration is performed on functionally less important retinal areas, while the pure subliminal coagulation treatment is performed in functionally important retinal areas.

By this device according to the invention the retinal treatment with the security of a calibration is made possible, which also designed the surgeon the degree of subliminal coagulation on the power setting selectable. Such a possibility of calibrating the device according to the invention thus provides a device for coagulation which offers particularly gentle irradiation and treatment of the retina. Preferably, the device comprises a display device, by which at least one mark can be displayed. Subliminally coagulated areas are not visible to an operator. By providing a marker, an operator can see the locations of those areas. As a result, areas of the retina can be marked so that the markers serve a surgeon during an operation as a thought support.

When using the device according to the invention for photocoagulation of the retina such that coagulation is sufficient for visual coagulation only at one or a few points of the coagulation spot, the presentation device can be represented by the at least one marker can be used for additional representation of coagulation spots. Therefore, an ophthalmoscopic surgeon can better recognize at what points of the retina coagulation occurs during and after treatment. As a result, the surgeon does not lose track of the treated areas of the retina during treatment. Otherwise there would be a risk that the surgeon will treat individual sites several times, or leave areas that need to be treated untreated. If the treatment is performed in several sessions, or several surgeons work one after another, it is even better for the surgeon to keep track of the treated areas. This eliminates the requirement that a surgeon remembers the treated areas and notes them on a form after the procedure.

The display device used is preferably a computer animation. In a computer animation, markers can be displayed at a certain distance from each other. You can use a 3D computer graphic or a 2D computer graphic. A 2D computer graphics will preferably created as a vector graphic. This consists of geometric shapes, and is therefore scalable. A 2D computer graphic could also be available as a raster graphic. Raster graphics consist of points that can be scaled with quality losses. More complicated images can be described even better with raster graphics.

Preferably, the positions of the subliminal coagulating laser spots are detected by a camera during coagulation, fed to a computer which registers the image of the coagulated retina at the time of laser triggering with a previously separately obtained image of the retina and there the position of the laser coagulation and its spot diameter stores. This position can either be displayed on a separate screen, faded into the application system, or projected onto the retina.

It is also preferable to supply the coordinates of the laser scanner to a computer, which determines therefrom the position of the laser photocoagulation.

Preferably, the presentation device comprises an output device. As output device, it is possible to use devices which are suitable for visualizing markings. The output of the markings can be temporary or permanent. Preferably, the output device is adapted to display markers in different colors. Particularly preferred are dispensing devices that can display markers in three dimensions. Also particularly preferred are dispensing devices that can move markings. The output device used is preferably a screen, preferably a color screen. As screens, for example, cathode ray tube screens, liquid crystal screens or plasma screens may be used. me be used. As an output device and means for generating holograms, printers or plotters can be used.

As an output device, an ophthalmoscope is preferably used, are inserted in the markers. The markers can be displayed both in a direct ophthalmoscope and in an indirect ophthalmoscope. A direct ophthalmoscope contains an illumination system, an observation system and correction lenses, and is arranged so that an examiner can view a patient's eye directly without an intermediate image being produced.

Preferably, the markers are faded into an indirect ophthalmoscope. In an indirect ophthalmoscope, an intermediate image is created, which is viewed by the examiner. In this case, the retina is observed with a light source, which is directed at a distance of approx. 50 cm from the patient's eye, and a magnifying glass, which is held approx. 2 to 10 cm away from the patient's eye.

Preferably, the markers are projected onto the retina. An operator can ophthalmoscopically view the markers together with the retina in this manner.

Markings are preferably easily recognizable. As markers, for example, light points can be applied. It can be used differently shaped, differently colored, three-dimensional, flashing or moving markings.

A three-dimensional display of the markings is preferably achieved by the display of two fields or a pair of images in a stereoscopic arrangement or with stereo images. scopic image information reached. In the following, for simplicity, only the term "fields" will be used, but this also means a pair of images in stereoscopic arrangement or with stereoscopic image information, each of which is made accessible to an eye Beam paths of a slit lamp or an ophthalmoscope, or by viewing the fields with an aid that makes each of the two fields accessible to a particular eye, can be achieved, for example, the color filters, Polfiltern or the alternate covering of an eye If the markings are projected onto the retina, the focal position of the projected markings is preferably adapted to the curved retina.

Preferably, a mark of a first type identifies a portion of the retina that has been treated with the beam of the radiation source. This makes it easy for the surgeon to keep track of treated areas.

As a marker of a first type, a marker as described above can be used.

The presentation device is preferably set up to mark areas of the retina intended to be treated with the beam with a marking of a second type. The surgeon can thus easily obtain an overview of the sites of the retina whose treatment is planned.

As a marker of a second type, a mark can also be used as described above. If markings gene of different types are used simultaneously, the markers preferably differ significantly from each other. This can be achieved, for example, by choosing different colors, shapes, size, geometry, or time-varying visual features. It is also possible for a marker of the second type to be shown flashing and to be displayed permanently as a marker of the first type in the same way after the treatment. Similarly, a marker of a second type could be displayed rotated when the corresponding area of the retina has been treated.

In particular, it is preferred if the presentation device is set up to deposit the marking with a background image. As a result, the position of the marker can be uniquely determined.

The background image should facilitate the orientation of the surgeon via the markers. This is preferably achieved by the use of a clearly structured background image, which divides the background into individual areas, or a representation of a retina. For this purpose, for example, a photo, a graphic, a movie or an animation can be set. Preferably, the background image makes the markings stand out clearly. For this background image and markers can be provided for example in complementary colors. Preferably, different background images are alternately shown behind the marks.

It is particularly preferable to use a coordinate system as the background image. Thus, the location of the individual markers is determined clearly in a simple manner. As a coordinate system, for example, a Cartesian coordinate system or a polar coordinate system could be selected.

Particularly preferred is the use of a Fundusaufnähme as a background image. This makes it particularly easy for a surgeon to mentally transfer the markings to the actual fundus image present to him.

As a Fundusaufnähme preferably a recording of the retina of the patient to be treated is used. It could also be used a recording of another retina. This would allow the surgeon to compare the retina of the patient being treated with another retina. Preferably, the images of different retinas are shown sequentially.

Particularly preferably, the background image is three-dimensional. This allows the background image to be adapted to the retina. The position of the markings can be reproduced so precisely. For the surgeon, it is so easy to transfer the markings into reality.

A three-dimensional background image is an image that additionally provides the observer with depth information for each point of the image. Preferably, a three-dimensional background image consists of two fields, which can be viewed directly or with suitable aids so that each is only perceived by one eye. A preferred

Possibility to view the image with tools is to color the two photos differently and to look at them with color filter glasses. The colors and color filters are chosen so that each one field through a color filter can be seen. Another way to make each eye a particular field visible is the polarization filter technique. In this case, the two fields are preferably projected onto the same position with projectors. In each case, 90 ° twisted polarizer films are located in front of the projection objectives. The observer views the projected image through polarizing glasses in which polarizer sheets are provided accordingly. Preferably, 3D images are viewed with a shutter glasses. For example, a monitor alternately displays the image for the right and left eyes. The eyewear covers accordingly alternately the right and left eye.

Most preferably, the background image is a live image. This allows the surgeon to consider changes that occur during surgery along with the markers.

As a live image, the current image of the retina of the patient is preferably shown.

Preferably, the display means is arranged to display a number of the areas of the retina which have been treated with the beam of the radiation source. The surgeon can quickly visualize how many areas of the retina he has treated.

This number is preferably displayed in a corner. As a result, the appearance of the markings is little affected.

This number is preferably displayed as a number or as a tick list. The number is preferably displayed in ascending order. But it is also possible at the beginning of the operation, the number of display planned treatment areas and count down during the operation.

It is expedient if the presentation device is set up to show markers and their processing online. This way, an operator can obtain information about the current status at any time during the operation.

In this case, the information that a marking is to be set is passed directly to the presentation device when treating the retina.

For example, to determine which areas to mark, a computer can get the information that a beam has been directed at the retina. Together with this information, the location and direction of the beam could be specified. From these three pieces of information, the computer can determine the point at which there is a coagulation point in the retina. The computer can then cause the display device to show a mark here.

The areas to be marked can also be determined by a camera which detects the retina during the treatment and a computer which recognizes the treated areas on the basis of the captured images. The camera could for example be attached to a laser slit lamp or a slit lamp with laser link.

In this case, it is particularly preferred if the device is provided with a memory device for storing the markings, the fundus recording and / or the coordinate system. With a new treatment, the markers can be displayed again. For example, semiconductor memories such as flash memories, magnetic memories such as hard disks, or optical memories such as CDs may be used as the storage medium.

The object is also achieved by a method for photocoagulating the retina, wherein a display device represents subliminally coagulated areas of the retina.

The presentation device preferably has a beam modification device, by means of which a beam of a radiation source with a distributed intensity profile is directed onto the retina, whereby a visually recognizable coagulation becomes recognizable only in regions of a maximum of the intensity profile.

Preferably, the presentation means marks subliminally coagulated areas of the retina.

The presentation device preferably has a camera through which regions of the retina that are treated with the beam of the radiation source can be detected. Thus, the treated areas are easily detectable.

The camera used is preferably a device that can capture images as still images or moving images.

The camera is preferably a still camera. The camera preferably images the retina at the time the retina is treated with the radiation source beam. As a result, exactly the information that is of interest to a surgeon is captured. As a camera, for example, a digital camera or an analog camera can be used. The use of a digital camera has the part that the images can be processed immediately by a computer. The use of an analog camera has the advantage that the images on a photo film are particularly well captured.

Particularly preferably, the camera is a movie camera. With the film camera, the retina is preferably taken from the beginning to the end of an operation. This ensures even better that all treatments of the retina have an image during surgery. Preferably, an electronic camera is used as the camera. As a result, the captured images can be captured with high quality. Particularly preferred as a camera, a video camera is used. As a result, the images can be recorded inexpensively.

Preferably, the presentation device has a computer, by means of which the regions of the retina which have been treated with the beam of the radiation source can be marked in a coordinate system or a fundus recording. In a computer computer, the information that a region of the retina has been treated with the beam of the radiation source, for example in the form of an image or by specifying coordinates. This information can then be processed and output by a computer. For output, a computer can mark the areas in a coordinate system or on a fundus image. The computer used is preferably an electronic circuit, particularly preferably a computer.

Preferably, the computer is set up such that markings can be faded into the observation beam path of an operator. Thus, the markers are displayed in a particularly comfortable way an operator. The observation Beam path of an operator, in which the markers are displayed, is preferably in a slit lamp, particularly preferably in an ophthalmoscope. In a slit lamp, a marker can be displayed in a particularly simple manner. The insertion into an ophthalmoscope is particularly expedient, since ophthalmoscopes are usually used in laser surgery.

The invention will now be illustrated with reference to figures, in which further advantageous embodiments are shown. In the figures shows:

Fig. 1 is a schematic plan view of a projected

Area and graphs for intensity distribution;

FIG. 2 shows an exemplary embodiment of an intensity profile according to the invention on a projected area; FIG.

3 is a schematic representation of an embodiment of a device according to the invention for photocoagulation;

4 shows a further embodiment of the photocoagulation device according to the invention;

5 shows a further embodiment of a beam modification device according to the invention;

6 shows a schematic representation of a diagram with an intensity profile and two examples of projected areas;

7 is a schematic representation of markings of the first and second type and FIG Fig. 8 is a schematic representation of an embodiment of a device according to the invention for photocoagulation.

In FIG. 1, A represents a projected area 12, on which an intensity maximum 16 is included. The homogeneous intensity profile of the laser spot thus has a region of higher intensity 16, which can be visually recognized during coagulation. FIG. A shows the intensity distribution in the plan view of the projected area 12 on a retinal level. The dark maximum 16 indicates a high radiation intensity.

Figure Bl shows the intensity profile along a section through the spot shown in Figure A along the indicated centerline. The intensity is low and constant in this cross section over a large area and increases in the region of the maximum 16. The image Bl is an ideal distribution of intensity, as it should be displayed on the retina.

In reality, due to the thermal conduction in the retina or retina, it may be advisable to calculate an intensity distribution deviating from this ideal case, which is then realized as a result of an intensity distribution on the retina after the thermal compensation effects. It may thus be necessary, for example, to set a corresponding maximum adjacent to a minimum which remains below the desired irradiation intensity, since thermal compensation effects are also taken into account, which still have an effect from the desired maximum. The retina is now destroyed only at the point of maximum 16. This site is for dose control. In the remaining area of the irradiated surface 12, coagulation remains subliminal, ie the retina remains largely functional.

FIG. 2 shows a projected area 12 on which a plurality of intensity maxima 16.1 to 16.4 are depicted. The intensity maxima 16.1 to 16.4 are arranged along the circular projected area 12 at the periphery thereof. These maxima 16.1 to 16.4 thus not only signal the achievement of the irradiation intensity but also the location at which the projected area was applied. Here, too, the area of subliminal coagulation (dashed line) dominates, while the individual maxima 16i occupy only a small part of the area. It is also possible to select three maxima which also visualize the area of the projected area 12 arranged on the circle plane. It is also conceivable that a maximum is arranged substantially continuously in the form of a ring, wherein the ring is preferably arranged around the center of the projected surface 12. The four dots depicted in Fig. 2 could thus constitute such a ring when joined together on a circle. In this way, the actual location of the coagulation after the treatment can be well recognized, although the subliminal coagulation can not be visualized. This simplifies subsequent post-treatment and localization of already coagulated areas. Preferably, the maximum can thus be realized as a ring or in the form of a donut profile. Especially with smaller spots this will allow a better localization. FIG. 3 shows a schematic structure of a device for photocoagulation 1. The photocoagulation device 1 comprises an optical waveguide 21 and an optical application system 20. The optical application system 20 comprises a first lens 22.1, a diaphragm 23 and a second lens 22.2.

A radiation source 10 is coupled to the optical waveguide 21 and emits a beam 11. This beam 11 is passed through the optical application system 20 and projected by the first lens 22.1 on the aperture 23. There, the beam 11 passes through and is focused by the second lens 22.2 on the retina or retina 5. On the panel 23, which in this case comprises a microstructured coating on a glass substrate, is thereby incorporated in the US Pat

In the laser zoom, an appropriate profile is introduced near an intermediate image plane of the laser beamed onto the retina. The beam is shaped in accordance with the profile specified here or stamped with a corresponding intensity profile. Preferably, the aperture 23 is interchangeable, so that different profiles in shape and transmission profile can be specified. The aperture 23 may also include controllable elements, such as small transmissive LCD panels, which allow a high degree of flexibility in the design of shape and intensity ratios. In this case, preferably, the intermediate image plane can be widened again, so that the LCD panels are not destroyed by the laser intensity. It is also possible to use micromirror elements such as Digital Mirror Devices (DMD). In this case, the optical beam path is preferably unfolded, since these elements operate in reflection. The optical application system 20 is here preferably designed as a zoom system. The beam 11 is thus characterized by the imprinted on the aperture 23 in the profile corresponding intensity distribution applied to the retina 5.

FIG. 4 shows a further exemplary embodiment of the photocoagulation device according to the invention. Here, an optical waveguide 21 is provided, via which the beam 11 is rectified by a lens 22 and is directed onto a free-form surface 24, which is formed as a deflection mirror. Thus, a corresponding profile is predetermined on the free-form surface, which has the now deflected beam 11 and thus causes an intensity profile 15 on the retina 5, as is indicated by the reference numeral 15 in FIG. 4 by way of example. The optics with free-form surfaces thus provide a further possibility for generating different intensity profiles. The deflecting mirror could also be designed switchable. A subsequent magnification / reduction optics could continuously change the scale and thus turn the profile on and off. Any other than round boundary would also be possible with this method.

FIG. 5 shows a further embodiment of a possible beam modification device 25. An optical waveguide 21 has a GRIN optic 26 formed at its end as an adapter. GRIN stands here as an abbreviation for "Grader / Index" or "Gradient / Index". In this optical element, the refractive index is location-dependent. For a GRIN lens, the refractive index changes continuously as a function of the path in the medium. In the GRIN optics 26 in FIG. 5, two small maxima are thus formed, which are arranged in section around the center of the then irradiated surface. The intensity distribution is thus transformed at the end of the fiber into the desired intensity distribution by the GRIN optics 26. This intensity distribution can then be further imaged by the previous optical system and thus transferred to the retina 5.

FIG. 6 shows an exemplary embodiment in which, in an initial calibration step, a wedge-shaped intensity profile over the beam cross-section is applied to the retina. In the diagram, the intensity distribution and this wedge-shaped intensity curve is shown, which drops over the diameter of the applied spot from 100% to 50% intensity. Illustrated in Figures A and B are projected areas 12a and 12b, which represent two different results on two different retinas. In Figure A, it can be seen that the coagulated area, which can be visually recognized, is about 50% of the area. This area is shown in dashed lines and can be seen on the left side in FIG. The right side is not recognizable coagulated. Considering that the intensity dropped from the left side of the intensity profile acting on the projected area 12a from 100% to 50% on the right side, it can be concluded that the visible coagulation occurred at intensities greater than 75% of the preselected intensity. In order to choose a value at which no visible coagulation occurs, the operator will want to select a value of less than 75%.

In the further irradiated projected area 12b, approximately 80% are coagulated along the wedge-shaped intensity distribution. Only 20% after that are not coagulated. The surgeon can therefore read that in his wedge-shaped intensity curve of 100% to 50% in this case only an intensity of less than 60% may be chosen so that no visible coagulation occurs. By means of this intensity profile, which is wedge-shaped over the beam cross-section and is applied to the retina, it can be detected in a patient-specific manner at which power density the coagulation threshold is exceeded. The subsequent coagulations are then carried out in the subliminal range with a homogeneous spot. Only in the calibration mode, a wedge-shaped intensity attenuator is pivoted into the beam path. This can be done for example as a gray wedge, dielectric gradient coating, micro-optically diffractive or refractive element or with the help of active elements such as Digital Mirror Devices (DMD). The calibration step is preferably carried out at the beginning of a treatment and can be repeated if necessary, for example, in the case of a significantly different absorbing retinal area. The calibration is preferably carried out in functionally less important retinal areas, while the pure subliminal treatment is preferably used in functionally important retinal areas.

The advantage of this embodiment of the invention is thus the subliminally coagulating, therapeutically effective retinal treatment with the security of a previously performed calibration, which is also configured selectable by the surgeon in the applied degree of subliminal coagulation on the previously selected power setting.

With the solution presented here, a device and a method has thus been provided, with which retinal coagulation can be carried out more gently, so that the retina can largely retain its function at the irradiated areas through the treatment and the corresponding feedback via visually recognizable coagulation centers , Figure 7 shows a schematic representation of markings of a first and a second type. The markings of a first type characterize areas of the retina which have been treated with a laser. The markers of a second type identify areas of the retina intended for treatment. The markers are displayed to an ophthalmologist during surgery through an ophthalmoscope.

The representation shown in FIG. 7a corresponds to an image which is displayed to a surgeon at the beginning of an operation. The representation shown in Figure 7b corresponds to an image displayed during an operation. The representation shown in FIG. 7c corresponds to an image which is displayed to an operator at the end of an operation.

FIG. 7a shows a polar coordinate system 31. The polar coordinate system 31 identifies different regions of the retina of a patient to be treated. On the polar coordinate system, markers of a second type are twelve

Distributed triangles. The triangles are shown here only as an outline. The surgeon would see them through the ophthalmoscope as red triangles. To the left of the coordinate system, two adjacent numbers are shown. The left number represents the number of treated areas and the right number represents the total areas to be treated. Here is the number "0" on the left and the number "12" on the right. Since FIG. 7a shows the image at the beginning of the operation, no treated areas are displayed here, but only twelve areas intended for treatment.

In contrast to FIG. 7a, FIG. 7b shows only five red triangles. At the points of the coordinate system where the remaining triangles are shown in FIG. 7a are here black filled squares can be seen as markings of the second type. The black-filled squares can be seen through the ophthalmoscope in the color green. To the left of the coordinate system, the numbers "7" and "12" are shown. In the state shown in Fig. 7b, 7 out of 12 areas intended for treatment have been treated.

Differing from FIG. 7b, FIG. 7c shows squares filled with black at the points where the triangles are to be seen in FIG. 7b. Further, in Figure 7c, to the left of the coordinate system, the number "12" is displayed twice, and in the state shown in Figure 7c, all twelve areas which were to be treated have been treated.

In each case one of the triangles shown in FIGS. 7a and 7b is displayed flashing to the operator. The blinking triangle indicates a portion of the retina next scheduled for treatment in a pre-planned order of treatment.

Displaying these markers allows the surgeon to see clearly during the surgery which areas have already been treated. He can also see which areas are still to be treated and which area is next for treatment. By displaying the numbers to the left of the polar coordinate system, the surgeon can quickly get an overview of the surgical progress. For the two markings, the colors red and green have been chosen, since they are well to decide from each other. The red triangle that marks the area next to treatment blinks because it is so conspicuous. Moreover, this is a way to make it clear that the area marked thereby belongs to the group of untreated areas heard, and still highlight it. For the polar coordinate system 30, the color black has been chosen because it is so clearly visible, but does not distract the surgeon's attention from the red triangles 27 and the green squares 28.

Figure 8 shows a schematic representation of an embodiment of a device according to the invention for photocoagulation. On the right side, an eye of a patient 32 is shown. An eye of an operator or a treating physician 38 is directed onto the retina or retina 5 of the eye 32 via an observation beam path 39. Via a first deflection device 34, a laser 10 is directed onto the retina 5. Via a second deflection device 36, a camera 35 is directed to the retina 5. The camera 35 is here attached to a not shown laser slit lamp or a slit lamp with laser link. The camera 35 is connected to a computer 37. The computer 37 has a connection to the observation beam 39.

The retina 5 is observed by the camera 35 during the operation or the treatment via the second deflection device 36. This will create a live image of the retina. The live image is forwarded to the computer 37. Based on this information, the computer 37 automatically detects the location of treated areas of the retina or the treatment point or treated areas at the time of irradiation with the laser 10 and the laser shot. The detected position of the treatment point or the location of the treatment is then marked or drawn in a coordinate system or a standard orientation system or a fundus recording of the patient. This is realized in this embodiment by the fact that the standard Orientation system for the retina is superimposed live with a fundus image of the patient.

By the computer 37, the marking or the point or the marking in the observation beam 39 of the treating physician 38 is superimposed or reflected. In addition, the coordinate system or standard orientation system is superimposed in the observation beam path 39. In addition, the current number of shots 30 and further treatment parameters are displayed in a corner of the visual field.

In the treatment shown here already treated areas have been read into the computer 37 and superimposed with the live Fundusaufnähme or a new Fundusaufnähme. Areas of the retina 5, which were intended for a treatment, or laser herds that have been planned prior to treatment with the help of a Fundusaufnahme be superimposed during surgery or treatment in the observation beam path. For later treatments, additional treatment points are displayed in the fundus image. To distinguish the markers for different treatments and for treatment planning, the markers are color-coded and have different shapes. Marks for treatment planning are shown as red crosses. Areas treated during treatment are marked with green circles. Areas treated in previous operations are marked with black dots.

After the treatment, the markings or the recorded treatment pattern or the treatment locations are stored by the computer 37 in a patient database. The fact that the treated places are saved, they can be recalled at a later treatment and re-displayed. An operator can thus obtain an overview of all treatments performed on one eye 32. A change of the surgeon is easily possible in this way.

The fact that a marked Fundusaufnähme or a marked standard orientation system is carried along with the current Fundusbild, receives an operator constantly feedback on the location of the treated areas or the positions of the already set shots. The surgeon has an up-to-date overview of previously treated areas at any time.

The detection of the treated areas with a camera 35 is an efficient and inexpensive solution for the detection of the treated areas. In addition, the collected data can be easily forwarded to a computer 37.

The insertion of the markings in the observation beam path 39 of an eye of an operator 38 is particularly convenient for the surgeon. He can see the markings when looking at the retina 5 at the same time.

LIST OF REFERENCE NUMBERS

Device for photocoagulation Retina Radiation source Beam Projected area Intensity profile Maximum intensity Optical application system Fiber optic lens Lens Iris Free-form surface Beam modification device GRIN optics Red triangle Red flashing triangle Green square Number of treated / treated areas Polar coordinate system Eye of a patient First deflection device Second deflection device Calculator Eye of an operator Observation beam

Claims

claims

1. Device (1) for photocoagulating the retina (5) comprising a radiation source (10) and an optical application system (20) characterized in that the optical application system (20) has a display device for displaying subliminally coagulated areas of the retina (5) ,

2. Apparatus according to claim 1, characterized in that the display device comprises a beam modification device (23, 24, 25) via which a beam (11) of the radiation source (10) in a predefined spatially distributed intensity profile (15) over the projected Surface (12) of the beam (11) is adjustable on the Netzhautebene.

3. A device according to claim 2, characterized in that the spatially distributed intensity profile is adjustable so that on the Netzhautebene at least in one area a visual coagulation can be generated.

4. Device according to claim 2 or 3, wherein the intensity profile (15) comprises one or more defined maxima (16) which, in sum, have an area of less than 20%, preferably less than 10%, particularly preferably less than 5%. the area formed by the projected area (12) of the beam (11) at the retina level.

5. Apparatus according to claim 4, wherein the intensity of the at least one maximum (16) in a nem fixed ratio to the intensity of the remaining range of the intensity profile (15) is adjustable.

6. Apparatus according to claim 5, wherein the intensity of the maxima (16) to visually visible

Coagulation is sufficient, while the intensity of the residual range of the intensity profile is less than 80%, the intensity of the maxima (16).

7. Device according to one of claims 4 to 6, wherein different maxima (16) from each other have different predefined intensities.

8. Device according to one of claims 2 to 7, wherein the intensity profile (15) is statically or dynamically generated.

9. Device according to one of claims 2 to 8, wherein the beam modification device (23) comprises a diaphragm with a defined profile.

10. Device according to one of claims 4 to 9, wherein the maxima (16) on a concentric ring around the center of the projected areas (12) of the beam (11) are adjustable on the retina level.

11. Device according to one of claims 4 to 10, wherein the maxima (16) can be generated temporally variable in a calibration mode.

12. Device according to one of the preceding claims, wherein at least one marking (27, 28) can be represented by the display device.

13. Device according to claim 12, wherein a region of the retina (5) which has been treated with the beam (11) of the radiation source (10) can be identified by a marking of a first type (29).

14. Device according to one of claims 12 to 13, wherein the display device is adapted to areas of the retina (5), which are intended to be treated with the beam (11), with a marking of a second type (28 ).

15. Device according to one of claims 12 to 14, wherein the display device is arranged to deposit the mark with a background image.

16. The apparatus of claim 15, wherein the background image is a coordinate system (31).

17. The device of claim 15, wherein the background image is a fundus image.

18. Device according to one of claims 15 to 17, wherein the background image is three-dimensional.

A device according to any of claims 15, 17 or 18, wherein the background image is a live image.

20. Device according to one of the preceding claims, wherein the display device is adapted to display a number of areas of the retina (5), which have been treated with the beam (11) of the radiation source (10).

21. Device according to one of the preceding claims, wherein the display device is adapted to show marks (27, 28, 29) and their processing online.

22. Device according to one of the preceding claims, wherein the device with a memory means for storing the markings (27, 28, 29), the Fundusaufnahme and / or the coordinate system (31) is provided.

23. Device according to one of the preceding claims, wherein the display device comprises a camera (35) through which regions of the retina (5) which are treated with the beam (11) of the radiation source (10) can be detected.

24. Device according to one of the preceding claims, wherein the display device comprises a computer (37) through which the areas of the retina (5) which have been treated with the beam (11) of the radiation source (10), in a coordinate system (31 ) or a Fundusaufnahme are markable.

25. Device according to one of the preceding claims, wherein the computer (37) is set up such that markings (27, 28, 29) can be faded into the observation beam path (39) of an operator.

26. A method of photocoagulating the retina, wherein a display means is subliminally coagulated areas of the retina.

27. Method for photocoagulating the retina, wherein a beam of a radiation source having a distributed intensity profile is directed to the retina, whereby a visually recognizable coagulation is recognizable only in areas of a maximum of the intensity profile.

28. A method of photocoagulating the retina, wherein the display means marks subliminally coagulated areas of the retina.