Method for marking of coagulation sites on a retina as well as a system for coagulating the retina

Abstract

A method for marking coagulation sites on a retina by application of a light source including projecting a serial spot sequence from a sequential, one-dimensional series of spots on the retina, wherein the individual spots indicate the coagulation sites; waiting for confirmation of the sequence of individual spots; after confirming, recalculating an automated sequence of steps having a further serial spot sequence and projecting them on the retina according to the first step; and subsequent repeating of the second and third steps. Also, a system for coagulating the retina, having an imaging diagnostic unit, a therapy beam for coagulating coagulation sites, a pilot beam for marking the coagulation sites by a spot sequence, a beam deflecting unit for generating the spot sequence and for positioning the therapy beam, an electronic control unit for controlling the above devices, a software interface, and an interactive interface.

Claims

1. A system for coagulating the retina; comprising: an imaging diagnostic unit; a therapy beam source generating a therapy beam that coagulates coagulation sites; a pilot beam source generating a pilot beam that marks the coagulation sites by a spot sequence; a beam deflecting unit that generates a spot sequence and that positions the therapy beam; a device for temperature determination that determines a temperature at the coagulation sites; an electronic control unit that is operably coupled to and controls the imaging diagnostic unit, the therapy beam source, the pilot beam source and the beam deflecting unit; and a software interface operably coupled to the electronic control unit; an interactive interface operably coupled to the electronic control unit; and an interrupter that, when activated, prevents at least one specific wavelength range of the therapy beam from impinging on the coagulation site; wherein the device for temperature determination determines the temperature at a selected coagulation site while the therapy beam is directed at said selected coagulation site; and wherein the device for temperature determination is connected to the interrupter indirectly via the control unit and the control unit controls the interrupter such that the interrupter interrupts the therapy beam if the temperature determined at a selected coagulation site exceeds a predetermined value, the predetermined value being selected to be wherein the retinal pigment epithelium is coagulated without damaging the overlying photoreceptors thereby sparing the photoreceptors and at least partially preserving light sensitivity at the selected coagulation site.

2. The system according to claim 1, wherein the imaging diagnostic unit comprises a laser slit lamp, a fundus camera, or a scanning laser ophthalmoscope.

3. The system according to claim 1, wherein the therapy beam source comprises a light source selected from the following light sources: LEDs, superluminescent diodes, gas discharge lamps and lasers.

4. The system, according to claim 3, wherein the therapy beam source generating a therapy beam that coagulates coagulation sites generates therapy beam pulse durations between 10 ms and 100 ms.

5. The system, according to claim 3, wherein the therapy beam source that coagulates coagulation sites generates therapy beam pulses by application of a microsecond laser.

6. The system, according to claim 3, wherein the therapy beam source comprises a multiwavelength laser producing laser energy in the visible range, in at least one of colors green, yellow, and red or in a near infrared.

7. The system, according to claim 3, wherein the therapy beam source that coagulates coagulation sites generates coagulation spots line by line or within a pattern.

8. The system, according to claim 1, wherein the therapy beam source generating the therapy beam includes a microsecond laser that emits micro-second laser pulses that coagulate the coagulation sites and wherein the beam deflecting unit generates the spot sequence and positions the therapy beam generates the spot sequence and positions the therapy beam line by line or within a pattern.

9. The system, according to claim 1, wherein the pilot beam source comprises a laser diode, which radiates in the red range.

10. The system, according to claim 1, wherein the beam deflecting unit coaxially projects the pilot beam and the therapy beam onto the retina.

11. The system, according to claim 1, wherein the beam deflecting unit comprises movable lenses, mirrors, or diffractive beam splitters in the beam path.

12. The system, according to claim 11, wherein the beam deflecting unit comprises lenses or mirrors that are controlled via motors; and wherein the motors comprise galvanometrically controlled mirrors, piezo scanners, or micromirror arrays.

13. The system, according to claim 1, wherein the interrupter comprises a device that deactivates the therapy beam.

14. The system, according to claim 13, wherein the interrupter comprises an aperture in an area through which the therapy beam passes.

15. The system, according to claim 1, further comprising a beam deflecting unit that generates the spot sequence and that positions the therapy beam line by line or within a pattern.

16. The system, according to claim 1, wherein the device for temperature determination comprises a detector that records pressure waves from the coagulation site.

17. The system, according to claim 1, wherein the therapy beam is emitted by a laser that emits micro-second laser pulses that coagulate the coagulation sites; and wherein the device for temperature determination comprises a detector that records pressure waves from the coagulation site and is connected to the interrupter indirectly via the control unit and further wherein the beam deflecting unit that generates the spot sequence and that positions the therapy beam generates the spot sequence and positions the therapy beam line by line or within a pattern.

18. The system, according to claim 1, wherein the system is adapted to irradiate every individual spot of the spot sequence by application of the therapy beam with an individual size, form, wavelength, and duration.

19. The system, according to claim 1, wherein the predetermined temperature is identical for all individual spots.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further details of the invention are described as follows by means of the attached figures:

(2) FIG. 1 shows a series of patterns of individual spots originating from one another through translation;

(3) FIG. 2 shows a series of patterns of individual spots originating from one another through rotation;

(4) FIG. 3 shows a series of patterns of individual spots originating through translation and change of the initial position as well as omission of a spot sequence;

(5) FIG. 4 shows two patterns of individual spots originating through translation and change of the length of the sequence;

(6) FIG. 5 shows a pattern of individual spots originating through translation, change of the starting point and length of the sequence;

(7) FIG. 6 shows a pattern of individual spots originating through translation and change of the distances between the individual spots;

(8) FIG. 7 shows patterns of individual spots originating through rotation of individual spots arranged on a circular arc;

(9) FIG. 8 shows patterns of individual spots originating through rotation of individual spots arranged as circle segment;

(10) FIG. 9 shows a pattern of coagulation sites originating through lateral change, change of size, change of the length of the sequence and the inner sequence distance;

(11) FIG. 10 shows a series of coagulation sites which are coagulated with different wavelengths;

(12) FIG. 11 shows a series of coagulation sites which are coagulated through different temperatures; and

(13) FIG. 12 depicts a system for coagulating the retina according to an example embodiment of the invention.

DETAILED DESCRIPTION

(14) FIG. 1 shows in the first depiction from the left the basic form of a sequential, one-dimensional series of individual spots, which serves as starting point for the additional depictions of FIG. 1 and their multiple applications, as described in the following.

(15) The series consists of eight individual spots which are arranged equidistantly to one another and run in vertical direction. The first individual spot is the depicted individual spot in the top position. Starting with said spot, the sequence is generated continuously from top to bottom in the depicted order.

(16) Starting from said basic form, a pattern of individual spotsdepicted in the second drawing from the leftarranged equidistantly to one another in a 716 matrix is obtained through a translation of the basic vertical series in the left drawing.

(17) Deviating from the basic form depicted in the first drawing from the left, the sequential, one-dimensional series can also exhibit a horizontal or other direction. Starting with the respective basic form, the patterns depicted in the additional drawings in FIG. 1 can be obtained. Thereby, the size of the matrix of individual spots arranged equidistantly to one another depends on the number of translations.

(18) The left drawing of FIG. 2 shows a shortened initial sequence with four individual spots when compared to the basic sequence in FIG. 1 with eight individual spots. The pattern in the second depiction from the left is obtained from the basic sequence in the left depiction in such a way that advancing from left to right one rotation each is achieved around a rotation center (not depicted) with an alternating sequence length between three and four individual spots, wherein the sequences with three individual spots are set in the gaps of the sequences with four individual spots. This is achieved in such a way that, in addition to the rotation, a translation of the initial individual spots is additionally executed in transverse direction.

(19) By contrast, the second drawing from the right in FIG. 2 shows a plain rotation between the first series of individual spots running in vertical direction and the second series slightly rotated counterclockwise as a result. The initial series as in FIG. 1 also exhibits eight individual spots, but the distance between the fourth and fifth individual spot is significantly greater. Said distance is chosen in such a way that no individual spots are present in a depicted circle. The rotation center is also the center of the depicted circle. A continuous and repeated rotation around the same angle of rotation indicated in the second drawing from the right in FIG. 2 results in the radial drawing on the right in FIG. 2.

(20) An irregular translation (which can also be called a modification of the initial position) is executed in the two left drawings in FIG. 3. Thereby, a vertical initial series of five individual spots is shown in the left drawing.

(21) The second drawing from the left shows a vertical initial series of six individual spots which similar to the two drawings on the right of FIG. 2 exhibits an increased distance between the upper half and the lower half (inner sequence distance) of the respective three individual spots.

(22) However, in the third drawing from the left in FIG. 3, a vertical series of seven individual spots is completed to a pattern through a consistent translation; however, said pattern is altered in respect of the form of the individual spots between the first and second (as well as the fifth and sixth) series relative to the third and fourth (as well as the seventh) series in such a way that the latter spot positions can be omitted by the operator, i.e., they do not constitute coagulation sites.

(23) The right drawing in FIG. 3 shows a special application, wherein the grey line represents a blood vessel. The operator omits those spot positions which would impinge on the blood vessel.

(24) In the two drawings on the left in FIG. 4, translations and changes in the sequence length with vertical symmetry of the spot sequence are superimposed. In the right drawing this leads to a pattern which represents a triangle with decreasing sequence length from left to right.

(25) In the drawing on the right in FIG. 4, a translation is also superimposed with a change of the sequence length of the spot sequence but the sequence length varies due to the absence of symmetry.

(26) FIG. 5 shows an irregular pattern which is obtained through the initial series of four vertical individual spots, as depicted on the very left, through varying the sequence length, translation, and change of the initial positions.

(27) FIG. 6 shows a pattern which is formed through translation of a basic form in vertical direction. Contrary to the previous patterns, the distances of the individual spots of the basic form are changed with every translation, resulting in a pattern in the form of a fanned out 66 matrix.

(28) The patterns in FIG. 7 and FIG. 8 are, in contrast to the previously described patterns, not based on the basic form of a sequential, one-dimensional series of individual spots in accordance with the drawing on the left in FIG. 1. Similar to the two drawings on the right in FIG. 2, no individual spots are present within the depicted circle.

(29) The drawing on the left in FIG. 7 shows the applied basic form as a circular arc of individual spots. Through a slight rotation, this basic form in the form of a circular arc results in the pattern depicted in the second drawing from the left, and a 180 rotation results in the pattern depicted in the third drawing from the left. Through multiple rotations in conjunction with the omission of spot positions by the operator, said basic form can be completed to a pattern in the form of a full circle.

(30) According to the drawing on the left in FIG. 8, a circular segment, wherein individual spots are arranged, is used as basic form in this embodiment. Starting with said basic form in the form of a circular segment, the pattern depicted in the second drawing from the left can be produced with a single rotation, and the third drawing from the left can be produced through multiple rotations. As can be seen in the drawing on the right in FIG. 8, the patterns can be reduced once again by the operator through omission of spot positions. Preferably, the inner arc forms the basic sequence in the circular segment. In order to fill the circular segment, the following sequence is produced on a greater radius, wherein, as a rule, the distance and the number of individual spots in the basic sequence are enlarged. This approach is advantageous because the innermost arc, i.e., the basic sequence, is placed near the macula where the demands are highest. Said demands decrease accordingly in the outward direction.

(31) The patterns shown in FIGS. 1 to 8 are only exemplary and can be modified arbitrarily for producing any desired pattern. This allows for a precise response to the individual case to be treated and for setting the patterns in such a way that coagulation occurs solely at the required coagulation points. The individual spots shown in FIGS. 1 to 8 are produced by the pilot beam, and the therapy beam will subsequently coagulate said sites.

(32) Based on a series of individual spots in horizontal direction, FIG. 9 shows a pattern, wherein the uppermost row was altered through modification of the sequence length as wells as the inner sequence distances. However, these are not the points marked by the pilot beam but the coagulation sites subsequently caused by the therapy beam. Hereby, the coagulation sites are varied according to the respective size of the coagulation site required for the individual case. Preferably, the diameters of such coagulation sites range from 50 to 500 m.

(33) In addition to a translation in vertical direction, a change of the diameter of the individual spots was also made between the lowest and second to lowest (and also between the second to lowest and second to highest) series of individual spots. However, between the second series from the top and the uppermost series, not only a partial change of the diameter of the individual spots was made (i.e., every other individual spot was reduced from the size in the second series from the top to a size according to the second series from the bottom) but also a sequence extension from four to seven individual spots as well as a change in the inner sequence distances was executed.

(34) FIG. 10 shows a grid of coagulation points with equal diameters which were irradiated with different wavelengths. Hereby, a wavelength of 577 nm was used for yellow light (550-580 nm), a wavelength of 532 nm for green light (514-550 nm), and a wavelength of 659 nm for red light (630-680 nm). The series from left to right is as follows: Yellow, green, red, green, yellow, green, red. Due to the different applied wavelengths, the primary absorption of energy in the retina takes place in different depths. As a result, coagulation occurs in the upper area of the retina due to the highest absorption of the blood pigment hemoglobin in the yellow spectral range. The highest absorption in the green wavelength range is caused by the photopigment melanin, resulting in coagulation in the medium depth of the retina. Red wavelengths cause the deepest penetration in the retina, resulting in the highest degree of coagulation.

(35) Due to the targeted irradiation of different coagulation sites with different wavelengths (colors), a depth modulation can be achieved. As a result, the individually required treatment can be taken into account.

(36) FIG. 11 shows the same row of coagulation sites as FIG. 10. However, in FIG. 11, a modulation with different coagulation temperatures instead of different light wavelengths is executed. Hereby, coagulation occurs monochromatic at a wavelength of, e.g., 532 nm (i.e., in the green wavelength range). Due to the different coagulation temperatures of, e.g., 45, 50, 60, different degrees of coagulation are achieved within the depicted coagulation sites. Thereby, the length of the arrows indicates the degree of coagulation in the retina, wherein long arrows represent a higher degree of coagulation than shorter arrows. This results in an equidistant, monochromatic coagulation degree-modulated laser coagulation or hyperthermia.

(37) Referring to FIG. 12, in an example embodiment, the system for coagulating the retina, having an imaging diagnostic unit 1, a therapy beam source 4 emitting a therapy beam for coagulating coagulation sites, a pilot beam source 5 emitting a pilot beam for marking the coagulation sites by means of a spot sequence, a beam deflecting unit 2 for generating the spot sequence and for positioning the therapy beam, an electronic control unit 8 for controlling the above devices, a software interface 9, and an interactive interface 10, is used for executing the method described above.

(38) By application of the imaging diagnostic unit, the operator can determine prior to executing the coagulation, at which concrete site of the retina said coagulation should be performed since the spot sequences marked by the pilot beam can now be observed. The therapy beam is used for coagulating the coagulation sites which were marked with the pilot beam beforehand. Therapy beam and pilot beam are controlled by beam deflecting unit 2 in such a way that the spot sequences of the pilot beam are projected onto the retina and that the therapy beam performs the coagulation on the marked individual spots after clearance through the confirmation by reception of the confirmation signal. The entire process is controlled by the control unit 8 which particularly controls the activation of the therapy beam source 4 as well as the beam deflection within the beam deflecting unit 2. The entire process is executed via a software interface 9. By use of the interactive interface 10, the confirmation by means of the confirmation signal is effected which is necessary for activating the therapy beam source 4 once the marking of the individual spots of the coagulation sites were indicated to the operator by use of the pilot beam.

(39) For example, the imaging diagnostic unit 1 is a laser slit lamp, a fundus camera, or a scanning laser ophthalmoscope.

(40) A number of therapy beam sources 4 light sources, such as LEDs, superluminescent diodes, gas discharge lamps, and particularly lasers are suited to emit the therapy beam. Thereby, a multiwavelength laser, which can emit different colors in the visible range, is used, for example. Particularly examples are the colors green, yellow, and red. Furthermore, it is also possible for the multiwavelength laser to emit light in the near infrared range. The different indicated wavelengths make it possible to reach different coagulation depths. Due to the photopigment melanin, the highest absorption takes place in the green wavelength range (from 514-550 nm); the highest absorption of the blood pigment hemoglobin is achieved in the yellow spectral range (550-580 nm); however, coagulation at a high tissue penetration takes place because of the red wavelengths (630-690 nm) or by means of a wavelength in the near infrared range (e.g., at 810 nm).

(41) For coagulating the retina, pulse durations between 10 ms and 100 ms, particularly between 20 ms and 50 ms, have proven successful for the therapy beam.

(42) Even though pulse durations below 20 ms ensure an almost painless treatment, the effect of the treatment must be expected to be inferior. By contrast, a superior treatment effect must be expected with pulse durations above 50 ms but which can lead to scarring of the treated sites.

(43) A high coagulation effect, wherein resulting scarring diminishes over time, is achieved with pulse durations between 20 ms and 50 ms. Therefore, pulse durations between 20 ms and 50 ms are recommended for the solution of coagulating the retina as described herein.

(44) A further embodiment of the invention provides for the pilot beam to be a laser diode which for example radiates in the red range. The resulting markings on the retina as already described above are easily identifiable by the operator.

(45) A further embodiment of the invention provides for the beam deflecting unit 2 to coaxially project the pilot beam and the therapy beam onto the retina. This ensures that the coagulation by means of the therapy beam takes place exactly at the position indicated beforehand by the pilot beam to the operator who cleared said position by entering of a confirmation signal. This ensures that the retina is not coagulated in sites which should not be coagulated, for example, because they still contain unimpaired tissue.

(46) A further embodiment of the invention provides for the beam deflecting unit 2 to exhibit movable lenses, mirrors, or diffractive beam splitters in the beam path. In prior art, these are well-known, reliable devices for beam deflection. Said lenses or mirrors are preferably controlled via motors; this particularly refers to galvanometrically controlled mirrors, piezo scanners, or micromirror arrays.

(47) A further advantageous development of the invention provides for the control unit 8 to be a microcontroller which exhibits at least one input interface and one output interface and which is programmable. This allows for previously determined values about the retina to be treated as well as the present ocular media to be entered into the control unit, which therefore knows the individually required data for the pending treatment and can adjust the respective series of individual spots to the present concrete conditions. As a result, it will not be necessary for the operator to periodically refuse clearance of the displayed series of individual spots and for the system to calculate and display to the operator an alternative series. Instead, every one of the displayed series can be cleared by the operator, leading to an accelerated treatment as well as increased reliability of the treatment.

(48) A further advantageous development of the invention provides also for an interrupter 3 which prevents at least one specific wavelength range of the therapy beam from impinging on the coagulation site. As already described above, the penetration of the radiation of the therapy beam, and therefore the coagulation, can be controlled through the use of different wavelengths. Therefore, the interrupter 3 specifies different penetration depths of the therapy beam at a predetermined individual spot or for an entire series of individual spots. In one example, said interrupter 3 is a filter which can be introduced into the therapy beam.

(49) A further advantageous development of the invention provides for the interrupter 3 to be a device which deactivates the therapy beam, particularly in the form of an aperture in the area through which the therapy beam passes. As a result, the coagulation can be altogether completed and not only selectively in one or different depths as is the case with the previously described filter.

(50) A further advantageous development of the invention additionally provides for a device for temperature determination 6 for determining the temperature at the coagulation site while the therapy beam is directed at said site. As already described above, the photoreceptor layer above the pigment epithelium to be treated can thereby be excluded from damage. Temperature determination is preferably effected by means of a detector 6 within the device for temperature determination, which records pressure waves from the coagulation site. Since the device for temperature determination is connected to the interrupter 3, the therapy beam can immediately be deactivated once the predetermined temperature is reached, resulting in the above-mentioned effect, i.e., the photoreceptor layer will not be damaged. Hereby, an indirect connection of the device for temperature determination 6 via the control unit can be provided in addition to the direct connection to the interrupter 3.

(51) A further advantageous development of the invention provides for the system to be prepared for irradiating every individual spot of the serial spot sequence through the therapy beam with an individual size, form, wavelength, and duration. This also serves the individual treatment of every site of the retina. By means of size and form, the treatment area at the respective site can be precisely adjusted to the desired size and form. By the wavelength adjustment, a specific depth of coagulation can be achieved within the retina, as already described above. As a result, a depth-modulated laser coagulation is possible for all coagulation sites. Through adjusting the duration, the temperature of the individual coagulation sites can be varied, resulting in the degree of coagulation of the retina. Therefore, a coagulation degree-modulated laser coagulation is possible for all coagulation sites. The size of the individual spots can be varied to a large extent; preferably the diameters are in a range between 50-1000 m. Thereby, the size of the individual spots can be modulated within a series of individual spots (which can be designed particularly as a straight line) or through a change of the sizes of the individual spots from line to line.