Abstract:
The present invention relates to a drugen treatment method and a method for controlling a drugen treatment device. The present invention provides a drugen treatment method comprising the steps of: confirming a location of drugen in a fundus of a patient; determining a treatment area by including a location on which the drugen exists; and removing the drugen by transferring energy to the treatment area.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the invention 
         [0002]    The present invention relates to a drugen treatment method and a method for controlling a drugen treatment device, and more specifically, to a drugen treatment method and a method for controlling a drugen treatment device that remove drugen by transferring energy to an area with drugen accumulations. 
         [0003]    2. Related Art 
         [0004]    A retina is a sensitive neural layer that is positioned on the fundus area of an eyeball to sense light. The macula is present at the center of the retina and neural cells called photoreceptors are collected at the macula. The photoreceptors are structured to emit light when illuminated and the macula with dense photoreceptors plays a critical role to view objects and maintain the central view. 
         [0005]      FIG. 1  is a cross-sectional view schematically illustrating the cross-sectional structure of a fundus. As shown in  FIG. 1 , a photoreceptor P including a plurality of cell layers is provided on the fundus area. At a lower side of the photoreceptor P are positioned the retinal pigmented epithelium cell (RPE cell) R and the Bruch&#39;s membrane B, and at a lower side of the Bruch&#39;s membrane is positioned the choroid C where a blood vessel passes. The choroid C supplies oxygen and nutrients to the inside of the retina through the Bruch&#39;s membrane B, and the RPE cell R supports the photoreceptor P while delivering the oxygen and nutrients supplied through the Bruch&#39;s membrane B to the photoreceptor P. 
         [0006]    As aging proceeds, wastes created in the retina are primarily accumulated in a space between the RPE cell R and the Bruch&#39;s membrane B or inside the Bruch&#39;s membrane B. The wastes are called drugen D. As drugen D are accumulated between the RPE cell R and the Bruch&#39;s membrane B, the RPE cell layer is separated from the Bruch&#39;s membrane B, thus causing dry age related macular degeneration. Further, as drugen D are accumulated, an inflammation occurs, secreting vascular endothelial growth factor (VEGF). This prompts the growth of new blood vessels. The new blood vessels grow into the retina, penetrating the weakened Bruch&#39;s membrane B, and thus, serious wet age related macular degeneration may develop. In a worse case, the vision may be lost. 
         [0007]    A widely used treatment method for such retina-related disease is antiangiogenic therapy to prevent the formation of new blood vessels. This method is to inject an anti-VEFG to suppress the abnormally growing VEGF, thereby stopping the vessel formation process. However, such treatment merely suppresses the growth of additional vessels and fails to completely respond to the same because drugen are still present between the RPE cell and the Bruch&#39;s membrane. Accordingly, continuous treatment should be followed to prevent the formation of more vessels. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention addresses the above issues and aims to provide a treatment method for fully removing the drugen left between the RPE cell and the Bruch&#39;s membrane. 
         [0009]    To achieve the above objects, according to the present invention, there is provided a drugen treatment method comprising identifying a position of drugen located in a patient&#39;s fundus, determining a treatment area including the position where the drugen are located, and transferring energy to the treatment area to remove the drugen. 
         [0010]    Here, the energy transferred to the treatment area may improve functions by which fundus tissues in the treatment area discharge the drugen to a choroid. Specifically, the energy transferred to the treatment area may improve a function by which a retinal pigment epithelium (RPE) cell adjacent to the drugen discharges a waste between the RPE cell and a Bruch&#39;s membrane to an outside of the Bruch&#39;s membrane. 
         [0011]    Here, transferring the energy to the treatment area is configured to transfer the energy to an RPE cell adjacent to the drugen. Transferring the energy to the treatment area is configured to transfer the energy by radiating light to the treatment area. Here, the amount of the radiated light absorbed by the choroid in the treatment area may be smaller than the amount of the radiated light absorbed by the RPE cell and larger than the amount of the radiated light absorbed by the photoreceptor. Specifically, the radiated light may have a wavelength of 510 nm to 590 nm. 
         [0012]    The radiated light may selectively increase a temperature of the RPE cell in the treatment area. In particular, a width at which a temperature of the choroid in the treatment area is increased by the radiated may be smaller than a width at which the temperature of the RPE cell is increased and may be larger than a width at which the photoreceptor is increased. Specifically, the radiated light may be pulse-type laser, and the laser may have a pulse width of 5 microseconds or less. 
         [0013]    Here, the step of transferring the energy to the treatment area may do thermal damage to the RPE cell in such a level as to induce regeneration of the RPE cell. The step of transferring the energy to the treatment area may be to terminate the energy transfer based on a signal generated from the treatment area. 
         [0014]    The step of determining the treatment area may be to set a boundary of the treatment area to an outside of a boundary where the drugen are located to be formed to be larger than the area where the drugen are located. Specifically, the step of determining the treatment area may be to determine to include the RPE cell located two to fifteen cells away from the boundary of the area where the drugen are located. 
         [0015]    On the other hand, the objects of the present invention may also be achieved by a method for controlling a drugen treatment device comprising determining a treatment area based on a position of drugen present in a fundus, transferring energy to the treatment area, and terminating the energy transfer based on a signal sensed in the treatment area. 
         [0016]    According to the present invention, in addition to restricting the lesion from further getting worse, drugen, the cause of the lesion, may be removed to enable complete treatment and restoration of the lesion. 
         [0017]    Further, the treatment method goes on in a non-invasive way using light, thus minimizing the patient&#39;s pain or resistance to the treatment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a cross-sectional view schematically illustrating a cross-sectional structure of a fundus; 
           [0019]      FIG. 2  is a view schematically illustrating the characteristics of light radiated to an RPE layer in a retina; 
           [0020]      FIG. 3  is a picture illustrating an example in which an RPE cell layer and the choroid are thermally damaged and then cultured; 
           [0021]      FIG. 4  is a graph illustrating a temperature distribution of a fundus tissue according to light pulse widths; 
           [0022]      FIG. 5  is a graph illustrating a temperature variation of a fundus tissue upon radiation of pulse-type light; 
           [0023]      FIG. 6  is a cross-sectional view illustrating an example in which a fundus tissue absorbs laser to create a variation; 
           [0024]      FIG. 7  is a block diagram schematically illustrating a drugen treatment device according to an embodiment of the present invention; 
           [0025]      FIG. 8  is a flowchart illustrating a drugen treatment method according to an embodiment of the present invention; and 
           [0026]      FIG. 9  is a view schematically illustrating the step of determining a treatment area in  FIG. 8 . 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0027]    Hereinafter, a drugen treatment method and method for controlling a drugen treatment device according to an embodiment of the present invention are described with reference to the drawings. In the following description, the locational relationship between the elements is shown primarily with respect to the drawings. The views in the drawings may be exaggerated as necessary or to simplify the structure of the present invention for ease of description. Accordingly, the present invention is not limited thereto, and other various devices may be added or changes or omissions may be made to the present invention. 
         [0028]    As described above, a fundus tissue includes a photoreceptor P including a multi-layered structure of optic nerves, an RPE cell layer R, and a Bruch&#39;s membrane B forming a boundary with the choroid C. The RPE cell layer R supplies oxygen and nutrients from the vessel of the choroid C to the photoreceptor P through the Bruch&#39;s membrane B and discharges wastes created from the photoreceptor P through the Bruch&#39;s membrane B to the vessel of the choroid C. 
         [0029]    Separation is rendered to arise between the RPE cell layer R and the Bruch&#39;s membrane B by the drugen that are accumulated between the RPE cell layer R and the Bruch&#39;s membrane B or in the inside of the Bruch&#39;s membrane B as the fundus tissue is aged. Accordingly, an insufficient amount of nutrients and oxygen is supplied to the RPE cell layer R and the photoreceptor P positioned with the drugen D accumulations, deteriorating various functions (a main cause of dry age related macular degeneration). Further, the deficiency of oxygen arising due to the drugen may induce the formation of new blood cells which then penetrate into the RPE cell layer and the Bruch&#39;s membrane, causing a high chance of the occurrence of wet age related macular degeneration. 
         [0030]    Accordingly, according to the present invention, there is provided a drugen treatment method for removing the drugen by applying energy to the area where the drugen are accumulated. Here, the energy provided to the area with the drugen D accumulations may be light energy. Various types of light may come in use. According to the instant embodiment, a laser beam with good wavelength selectivity is put to use. However, other various light sources, such as a laser, a laser diode, an LED, and a lamp, may be used. 
         [0031]    As shown in  FIG. 2 , light of a wavelength with good absorption characteristics may be applied to the RPE cell layer containing pigment such as a melanosome M, and light with poor absorption may be applied to the photoreceptor. In such case, damage to the photoreceptor may be minimized. 
         [0032]    A test result shows that light with a wavelength of 510 nm to 590 nm is nearly not absorbed by the photoreceptor P and is rather substantially transmitted. The light of the wavelength is absorbed by the RPE cell layer R by 50% or more, and part of the light passing through the RPE cell layer R is absorbed by the choroid C. Such nature is shown more noticeable for light with a wavelength of 520 nm to 540 nm. 
         [0033]    As such, as the area with the drugen D accumulations is energized, the fundus tissues adjacent to the drugen are rendered to present improved characteristics in a predetermined time, discharging the drugen present between the RPE cell layer and the Bruch&#39;s membrane or inside the Bruch&#39;s membrane towards the choroid. This is considered to come from an improvement in the pumping characteristics, i.e., transportation, of the RPE cell layer. 
         [0034]    The RPE cell is an excellent self-regeneratable tissue. This may also be verified from the result obtained by culturing the RPE cell layer and choroid thermally damaged by selective light radiation, as shown in  FIG. 3 . Accordingly, as the RPE cell layer is damaged by radiating a wavelength of light with good tissue selectivity, the RPE cell layer actively proceeds with the self-regeneration process, restoring the various functions deteriorated due to aging. By such regeneration process, the RPE cell layer R has an improved pumping characteristic, thus making better the characteristic that the drugen D is discharged to the outside of the Bruch&#39;s membrane B. 
         [0035]    Here, as shown in  FIG. 4 , the fundus tissue may experience different temperature rise characteristics depending on pulse widths of light radiation as shown in  FIG. 4 . Although the photoreceptor P absorbs little light, a photoreceptor P adjacent to the RPE cell layer R with good light absorption characteristic may go through a temperature rise due to the heat transferred from the RPE cell layer. Thus, what may be used is light having a pulse width that may minimize damage to the photoreceptor P while selectively raising the temperature of the RPE cell layer to cause thermal damage thereto, and the pulse width of the light (the pulse width is the duration when one pulse of pulse-type light is radiated) may be not more than 5 us. Such characteristics may be more noticeable when the pulse width is not more than 2 us, and the light with a wavelength of 520 nm to 540 nm, when it has a pulse width of substantially 1.7 us, has been observed to present such characteristics better. In this case, the RPE cell layer R experiences a largest temperature rise, and the temperature of the choroid C is subjected to a steady rise. However, the photoreceptor P, even though positioned adjacent to the RPE cell layer R, experiences little rise in temperature. 
         [0036]      FIG. 5  is a graph illustrating a temperature variation of the RPE cell layer and the photoreceptor when illuminated with pulse laser. As shown in  FIG. 5 , the RPE cell layer R, when radiated with light, presents a temperature rise high enough to cause thermal damage thereto for each pulse. By contrast, the photoreceptor P, although showing a tiny temperature variation for each pulse, fails to reach a level at which damage occurs. As such, the present invention may induce the regeneration of the RPE cell without damaging the photoreceptor through selective retina treatment. 
         [0037]    As set forth above, energy provided may be of level at which the adjacent photoreceptor P is prevented from damage and the incurred thermal damage is done so that the 
         [0038]    RPE cell R may go on with self-regeneration. Thus, the supply of energy to the spot where the drugen D are accumulated may be terminated based on a predetermined signal generated from the tissue. 
         [0039]    Here, the signal generated from the tissue may mean various signals. The signal may be a signal created by the thermal damage by the energy provided, and such signal may be in various forms such as an optical signal, a sound wave-wise signal, or an electrical signal. What may be used among them may be a signal generated by a micro cavitation (mc) created as the melanosome M of the RPE cell R, upon light radiation, absorbs the energy and thus the temperature rises. As shown in  FIG. 6 , the RPE cell radiated with light is expanded due to the creation of the micro cavitation as the temperature rises. Whether the micro cavitation occurs may be sensed by analysis of light reflected, and use of the same enables the sensing of whether the RPE cell R is thermally damaged and then the control as to whether to provide energy. 
         [0040]    By the above-described method, when energy is applied to the area where the drugen D are created, adjacent tissues, such as the RPE cell layer R or the Bruch&#39;s membrane B, present improved discharge characteristics, thus enabling the elimination of the drugen D towards the choroid. In such case, the energy may be selectively provided to the RPE cell layer at the corresponding position, so that the pumping capability of the RPE cell layer may be improved by the vigorous self-regeneration capability of the RPE cell while preventing damage to the adjacent photoreceptor. 
         [0041]    Now described in further detail are a drugen treatment method and drugen treatment device for implementing the same, using the above description with reference to  FIGS. 7 and 8 . 
         [0042]      FIG. 7  is a block diagram schematically illustrating a drugen treatment device according to an embodiment of the present invention.  FIG. 8  is a flowchart illustrating a drugen treatment method according to an embodiment of the present invention. 
         [0043]    As shown in  FIG. 7 , the drugen treatment device may include a test unit  10 , a control unit  20 , a light source  30 , a beam delivery unit  40 , and a signal detection unit  50 . 
         [0044]    The test unit  10  may be a device for identifying the position of drugen D. Various fundus picturing devices that may detect the position of drugen may be used as the test unit  10 . The test unit  10  may be provided integrally with the drugen treatment device or separately from the drugen treatment device. 
         [0045]    The control unit  20  may set a treatment area based on the information on the position of drugen identified by the test unit  10 . The control unit  20  may be configured to control the content of driving the light source  30  and the beam delivery unit  40  and may adjust the output and radiation pattern of light radiated to the treatment area. 
         [0046]    The light source  30  generate light energy to be transferred to the treatment area. In this case, the light source  30  radiates a wavelength of light that has a high absorption characteristic to the RPE cell layer R to induce thermal damage to the RPE cell layer R and that has a pulse width at which the photoreceptor P may be prevented from damage, thereby enabling SRT treatment. As an example, in the present embodiment, the light generated may have a wavelength of 510 nm to 590 nm, more specifically, 527 nm, and a pulse width of 5 us or less, more specifically, 1.7 us. 
         [0047]    The beam delivery unit  40  is a component that transfers light generated from the light source  30  to the treatment area. The beam delivery unit  40  may include a plurality of scanners constituted of reflecting mirrors and various optic components. The beam delivery unit  40  is controlled by the control unit  20  and enables light to be radiated to a preset position of the treatment area according to a preset pattern. 
         [0048]    Meanwhile, the signal detection unit  50  may detect a signal transferred from the treatment area. When the light is radiated to the treatment area by the beam delivery unit  40 , the tissue of the treatment area is varied by the transferred energy, and accordingly, various forms of signals may be presented. The signal detection unit  50  may identify whether the treatment area experiences a tissue variation by detecting the signals. In the instant embodiment, it may be configured so that the occurrence of micro cavitation in the RPE cell R may be detected through sound wave information reflected or phase information on the reflected light when light is radiated. 
         [0049]    Although the drugen treatment device  1  according to the present invention has been schematically described, this is merely an exemplary configuration for describing the present invention, and various changes may be made thereto. 
         [0050]    In connection with  FIG. 8 , a drugen treatment method and method for controlling the treatment device using the drugen treatment device  1  of  FIG. 7  are described. First, the step of detecting the position of drugen to treat the drugen D is performed (S 10 ). This step is performed by the test unit  10 , such as the above-described fundus picturing device or fundus tomography device, and an image captured by the test unit  10  may be analyzed to detect the position L1 of the drugen distributed in the fundus. 
         [0051]    When the position L1 of the drugen is detected, the step of determining a treatment area L2 may be conducted (S 20 ). The treatment area L2 may be determined to include the position L1 of the drugen. The tissues involving the discharge of the drugen D are involved in tissues at exactly the same position as the drugen as well as tissues positioned adjacent thereto. Accordingly, the step of determining the treatment area, as shown in  FIG. 9 , may be set to be larger than the area where the drugen are positioned by setting a boundary of the treatment area L2 to be outside the boundary of the area where the drugen is located. 
         [0052]    The boundary of the treatment area L2 may be set to be 10 um to 200 um or more away from the boundary of the area where the drugen is positioned. As another example, the boundary of the treatment area may be set to include the position where two through up to 15 RPE cells are positioned apart from the boundary of the area where the drugen are positioned. 
         [0053]    Meanwhile, when the treatment area is determined, the step of transferring energy to the treatment area is performed (S 30 ). In the step of transferring energy to the treatment area, the wavelength, pulse width, and radiation pattern of light may be determined by the control of the control unit  20 , and the light source  30  and the beam delivery unit  40  may be driven corresponding to the same, thereby transferring energy. Here, as described above, light that has a wavelength of 510 nm to 590 nm, specifically, 527 nm, and a pulse width of 5 microseconds or less, specifically, 1.7 microseconds, may be radiated. 
         [0054]    As such, when the energy is transferred to the treatment area, the energy, by its wavelength nature, is absorbed primarily by the RPE cell layer R, so that the RPE cell layer R goes through a temperature rise and resultantly thermal damage. In this step, the light is partially absorbed by the choroid C as well as by the RPE cell layer that may then thus experience a temperature rise. However, the light may substantially pass through the photoreceptor P rather than being absorbed. 
         [0055]    While the instant step goes on, the signal detection unit  50  may be configured to measure and detect a signal generated from the fundus by the continuous energy transfer. The signal here may be a signal generated by the thermal damage that is done to the fundus tissue by the transferred energy, specifically, a signal generated by a micro cavitation that may be created by the evaporation of the melanosome M inside the RPE cell layer R. In the energy transfer step, when radiating pulses of light to the same spot, the light output may be controlled to be increased for each pulse and be radiated in order to facilitate to reach the time of generation of the signal. 
         [0056]    Upon sensing a signal originating from a tissue variation while energy is transferred to a particular spot of the treatment area, the control unit  20  may adjust the energy transferred to the treatment area based on the signal (S 40 ). For example, when the micro cavitation is identified as occurring, control may be performed so that the RPE cell R at the position may be considered to have been thermally damaged sufficiently to perform a regeneration process, pausing the energy supply. Or, when the micro cavitation is identified as occurring, control may be conducted so that a predetermined radiation pattern of light is radiated from the time that the micro cavitation is identified and is then terminated. 
         [0057]    It may be considered that the treatment is done at one spot through the above steps, and the radiation position may be changed to a next spot in the treatment area using the beam delivery unit, and the above-described treatment steps may then be repeatedly performed. 
         [0058]    The above-described drugen treatment method may lead to improvements in functions of tissues adjacent to the position with the drugen accumulations, i.e., the RPE cell and Bruch&#39;s membrane, so that the drugen may be discharged to the choroid, thus enabling the removal of the drugen in the retina. Accordingly, fundamental treatment may be done for patients with dry age related macular degeneration while effectively cutting off the likelihood of developing to wet age related macular degeneration. 
         [0059]    Although the present invention has been described in connection with embodiments thereof, the present invention is not limited thereto and various changes may be made thereto without departing from the scope of the present invention defined in the following claims.