RU2611887C1 - Method for selecting parameters of laser treatment of retinal diseases - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to ophthalmology, and can be used for selection of parameters of laser treatment of retinal diseases. Laser test applicates Nd:YAG are applied by laser on retina in tested zone, identical in thickness and pigment distribution to zone of planned performance of laser coagulation. A series of ophthalmoscopically visualisable laser applicates are applied using wavelength 561 nm, pulse duration 100 ms, duty cycle 100 ms, power from 70 to 100 mW. After that, three series of ophthalmoscopically non-visualisable laser applicates are applied with reduction of pulse duration first by 50%, then by 90%, then simultaneously with 90% reduction of pulse duration, power is reduced by 20%. Immediately after impact optic coherent tomography of tested zone is performed. Obtained scans are used to determine tested laser applicates with minimal parameters, producing therapeutic effect.

EFFECT: method makes it possible to increase accuracy and objectivity of selecting parameters of laser coagulation of retina with absence of side effects and allergic reactions in carrying out test examination and, thus increase efficiency of laser treatment of retinal diseases.

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Description

The invention relates to medicine, namely to ophthalmology, and is intended to select the parameters of laser treatment of retinal diseases.

Depending on the type of tissue and wavelength, laser radiation can be uniformly absorbed by chromophores and water, or discretely by pigment granules. During absorption, the energy of laser radiation is transformed by absorbing structures into internal energy (thermal). Depending on the exposure time, these effects can occur not only in adsorbing structures. During and after exposure, heat spreads around the absorbent volume, as a result of which the temperature of the surrounding tissues rises significantly and undesirable side effects develop. The transition from local to widespread thermal damage occurs when the exposure time exceeds the relaxation time required for thermal damage to the structures. During prolonged exposure, heat transfer and relatively uniform heating of adjacent tissues occur, leading to the development of nonspecific necrosis. If the pulse duration is shorter than the temperature relaxation time, a spatial limitation can be achieved because the temperature increase outside the damaged structure occurs in such a small volume that it cannot lead to the development of any significant collateral damage. However, for short pulses, a high temperature in the damaged structure is necessary to achieve damage. When a high temperature gradient is reached, thermomechanical mechanisms, such as the explosive effect, begin to compete with purely temperature effects (Roider J. Laser treatment of retinal diseases by subthreshold laser effects // Semin. Ophthalmol. - 1999. - 14, N1. - P. 19-26).

A number of authors have proved that laser coagulation, capturing only the outer layers of the retina, without capturing the inner nuclear layer, leads to proliferation of TEC and glial cells, as well as closure of leakage sites (Wallow IHL, Bindlei CD Focal photocoagulation of diabetic macula edema: a clinicopatologic case report / / Retina. - 1988 .-- 8. - P. 261-269).

Roider J. (Roider J. et al. Subthreshold (retinal pigment epithelium) photocoagulation in macular diseases: a pilot study // Brit. J. Ophthalmol. - 2000. - 84, N1. - P. 40-47) proposed a concept, based on the properties of repetitive short pulses. A specific combination of the duration of the pulses, their number, energy and repetition time leads to the achievement of a sufficient level of temperature in the damaged structure and to obtain the expected damaging effect. The concept is based on two reasonable assumptions.

Each single pulse will lead to a large increase in temperature for a short time, which will cause thermal damage to the absorbent structure. During interpulse time, the temperature quickly drops to the level of body temperature. Heat diffusion smoothes out significant temporal thermal modulations, and the increase in temperature outside the adsorption volume is limited by depth modulation. If the exposure parameters are selected properly, a short significant temperature deviation in the damaged structure will cause its complete damage after exposure and will be achieved by a certain number of sub-damaging pulses. In contrast, a slight increase in the temperature of the surrounding tissue will not lead to the development of damage. Even if thermomechanical effects cannot be excluded, an increase in temperature as a result of each single impulse leads to the development of mechanical effects, the intensity of which is below the damaging level.

энергии непрерывного импульса, приводящего к легкому побледнению пигментного эпителия сетчатки (ПЭС) (Lanzeta P., Dorin G., Pirracchio A., Bandello F. // Theoretical bases of non-ophthalmoscopically visible endpoint photocoagulation // Semin. Ophthalmol. - 2001. - 16, N1. - P. 8-11). Этот метод имеет ряд недостатков: субъективность оценки, различное распределение пигмента и толщины сетчатки в зоне подбора энергии и зоне операции.The prior art method of selecting parameters for laser treatment of retinal diseases, which consists in the fact that when conducting laser coagulation of the retina (LKS), the energy of each pulse in the series corresponds to

energy of a continuous pulse, leading to a slight pallor of retinal pigment epithelium (PES) (Lanzeta P., Dorin G., Pirracchio A., Bandello F. // Theoretical bases of non-ophthalmoscopically visible endpoint photocoagulation // Semin. Ophthalmol. - 2001. - 16, N1. - P. 8-11). This method has several disadvantages: subjectivity of the assessment, different distribution of pigment and retinal thickness in the energy selection zone and the operation zone.

Also known from the prior art is a method of selecting parameters for laser treatment of retinal diseases, which consists in the fact that prior to the operation (laser coagulation of the retina) a series of test applicates is applied in the lower temporal arcade region with different pulse powers. Test burns are not visible during or immediately after the procedure, and also, usually after 2 hours. 2 hours after the test intervention, fluorescence angiography (FAG) is performed. Then, based on the data of the “test” phage, the pulse power required for treatment is selected. Laser coagulation of the retina is performed using the selected minimum energy power, causing damage to the TEC, identified by phage. Damage to PES was defined as bright hyperfluorescence 2 hours after the test intervention. This method is more objective, but longer.

Unfortunately, the proposed methods for the selection of LC parameters allow an assessment of the results only a few hours after applying a series of trial coagulates, which significantly increases the treatment time. In addition, the conduct of phage is limited by burdened allergic history in patients.

Further, from the prior art there is a known method for selecting parameters for laser treatment of retinal diseases, which consists in the fact that prior to the LKS operation, a series of test applicates are applied, identified by the method of microfluorescence angioscopy, based on the use of a bandpass filter that transmits radiation in the area of fluorescein luminescence, after which , based on the data of microfluorescence angioscopy, choose the pulse power necessary for treatment (Pasechnikova N.V. Laser treatment for eye pathology on the bottom. Kyiv, 2007, 206 pp.). But when using this filter, only pathological zones are visible where the choroid is visible through the TEC. When conducting the study, it must be taken into account that the brightness of the fundus is not constant during the phases of the dye circulation. The accumulation of fluorescein with moisture in the anterior chamber of the eye is also important for artifacts. Visually, the rest of the fundus looks black, which limits the ability to see anatomical landmarks when conducting LKS, there is a greater likelihood of adverse events (edema, hemorrhage, retinal detachment, dystophic changes).

The prior art method for selecting parameters for laser treatment of retinal diseases, which consists in applying laser test Nd: YAG laser applicates to the retina in the test area, which is identical in thickness and pigment distribution to the area of the planned laser coagulation, identifies test applicates and selects the minimum laser coagulation parameters, giving a therapeutic effect, while test applicants are identified using the phenomenon of autofluorescence to assess selective damage to the TEC with K (Framme C. et al Autofluorescence imaging after selective RPE laser treatment in macular diseases and clinical outcome: a pilot study, Br J Ophthalmol, 2002, 86, p 1099-1106..). Retinal autofluorescence more clearly shows changes in retinal pigment epithelium (RPE). The principle of autofluorescence is based on the ability of lipofuscin granules, which accumulate in PES cells, to fluorescence. Lipofuscin, also called the “old age pigment”, which is a fragment of the metabolism of the outer segments of the photoreceptors, by its chemical nature is a lipid-protein complex, the autofluorescence of which occurs when irradiated with light with a short wavelength. Since energy is absorbed during laser irradiation by PES melanosomes, laser irradiation significantly changes the autofluorescence pattern. However, the use of autofluorescence has significant limitations: a pronounced decrease in the phenomenon of autofluorescence manifests itself in the region of the macula (due to macular pigment), which makes it impossible to determine central coagulates; certain difficulties arise when it is not possible to register the phenomenon of autofluorescence due to thinning of the retina and extensive edema.

Thus, there is a need for a method of selecting parameters for laser treatment of retinal diseases, excluding the introduction of fluorophores, while sufficiently accurate, objective, allowing you to select the optimal parameters for the treatment of retinal diseases.

In accordance with this, the technical result is to increase the accuracy and objectivity of the choice of LKS parameters in the absence of adverse and allergic reactions during the test study.

To solve this problem, in a method for selecting parameters for laser treatment of retinal diseases, including applying laser test Nd: YAG laser applicates to the retina in the test area, which is identical in thickness and pigment distribution to the zone of the planned laser coagulation, identifying test applicates and choosing the minimum parameters giving therapeutic effect, first a series of ophthalmoscopically visualized laser applications is applied using a wavelength of 561 nm, a pulse duration of 100 ms, a duty cycle of 100 ms , power from 70 to 100 mW, then apply three series of ophthalmoscopically non-visualizable laser applicates, reducing the pulse duration first by 50%, then by 90%, then simultaneously with the pulse duration reduced by 90%, reduce the power by 20%, and then immediately identification of test applicates using optical coherence tomography of the test area, and test laser applicates with minimal parameters giving a therapeutic effect are determined from the scans obtained.

The method is as follows.

In FIG. 1-3 are the steps of the proposed method. A series of laser applicates is applied to the retina in an area identical to the damage zone (by thickness, blood supply and pigment distribution), using a focused Nd: YAG laser beam using a laser unit (we used VISULAS TRION Karl Zeis Jena (Germany)). First, a series of ophthalmoscopically visualized laser applicates is applied (wavelength 561 nm, pulse duration 100 ms, duty cycle 100 ms, power from 70 to 100 mW) (Fig. 1 - phage image, for clarity), starting with the visualized applied applicate (pale white ) 1 degree according to L'Esperance (1). Then, the application time is reduced by 50%, causing an ophthalmoscopically non-visualizable effect on the tissue (2), then this time is reduced by 90% (3), after which, in addition to the exposure time reduced by 90%, the power is reduced by 20% (4).

Using OCT scans obtained immediately after a series of these interventions (Fig. 2a), test coagulation applications were determined that were not visualized during and after the LKS procedure (2), (3), (4). Given that OCT is a highly informative diagnostic method that allows real-time cross-sectional imaging with a resolution of 1 to 10 μm, it is possible to obtain high-precision cross-sections of the studied tissues by visualizing the rays reflected from the obstacle and measuring the intensity of scattered or reflected light from interstitial microstructures and process the image of choriocapillaries and retinal pigment epithelium with the possibility of analyzing reflectivity (identifying areas of hypo- and hyperreflectivity). From the obtained radiation parameters, the minimal ones giving a therapeutic effect were chosen, which were used in the course of further operations - (2 ') (Fig. 1). The ratio of therapeutic and damaging effects is estimated by the width (1), (2), (3) of the displayed laser applicate (Fig. 3) on OCT scans: ophthalmologically non-visualized applicates with minimal parameters giving a therapeutic effect, at least one third of the thickness and not more than half the thickness of ophthalmoscopically visualized laser applicates (1). In FIG. 3 applicate with optimal parameters is applicate (3).

Additional OCT scans performed 2 hours after the application of test interventions (Fig. 2b) and three days later (2c) clearly reflect the dynamics of the laser damaging and therapeutic effects.

Our proposed method for selecting parameters for laser treatment of retinal diseases allows laser coagulation of the edema region, minimizing damage caused by laser radiation, and thereby reduce the possible delayed complications and destructiveness of laser intervention. The choice of power within the specified range depends on the intensity of retinal pigmentation and the thickness of the retinal edema.

Example. Patient K., age 74 years. Received in the ophthalmology department of GBUZ MO MONIKI in May 2015.

Complaints: the appearance of "fog", blurred vision, floating blurred right eye from December 2014

Anamnesis: Visual acuity of the right eye decreased suddenly in the morning after waking up. It was treated on an outpatient basis with a slight positive effect.

Concomitant diseases: Hypertension III, arterial hypertension 2 tbsp .; Coronary heart disease, postinfarction cardiosclerosis (2010).

Initial Inspection Data:

Visual acuity: Vis OD = 0.4 n / a IOP 21 mmHg (according to Maklakov). Vis OS = 0.7 n / a IOP 21 mmHg (according to Maklakov).

Diagnosis: Thrombosis of the superior temporal branch of the central retinal vein of the right eye (at the site of arteriovenous intersection) diffuse macular edema, initial age-related cataract of both eyes.

Ophthalmoscopically: on the fundus of the right eye, the optic nerve disc is pale pink, the borders are clear, excavation is 0.4, retinal edema in the affected sector, expansion and tortuosity of the upper temporal branch of the central respiratory tract, multiple intraretinal hemorrhages with the capture of the parafeal zone (Fig. 4). On OCT of the retina of the left eye: diffuse edema is differentiated with single small cystic cavities, an area of more than 8D of the disk, the thickness of the retina in the central zone is 319 μm, the maximum height of the edema in the zone of damage to the vessel is 425 μm (Fig. 5).

According to the phage, an increase in venous perfusion time, pronounced areas of hyperfluorescence due to sweating, there are also areas of hypofluorescence corresponding to more than 12D disc ZN, corresponding to impaired perfusion of the choriocapillary layer (Fig. 6).

In accordance with the proposed method, the patient was applied with laser test Nd: YAG laser applications on the retina in the test area, which is identical in thickness and pigment distribution to the area of the planned laser coagulation — in the area of the inferior temporal branch of the CVC. First, a series of ophthalmoscopically visualized laser applications (grade 1 according to L’Esperance) was applied using a wavelength of 561 nm, a pulse duration of 100 ms, a duty cycle of 100 ms, and a power of 80 mW. Then, three series of ophthalmoscopically non-visualizable laser applications were applied, reducing the pulse duration first by 50%, then by 90%, then simultaneously reducing the pulse duration by 90%, reducing power by 20%. Immediately after that, we identified (Fig. 7) the test applicates (1), (2), (3), (4) using optical coherence tomography of the test area, and from the scans we determined the test laser applicates with the minimum parameters (3), giving a therapeutic effect (A - fragment of the control image of phage, B - fragment of the OCT scan). The patient underwent laser coagulation according to the proposed method with the selection of individual doses of laser exposure: 1,500 coagulation applications with a diameter of 50-300 microns, with a distance between them of 100-300 microns, a laser with a wavelength of 561 nm, a pulse duration of 10 ms, and power were applied to the edema zone 80 mW. The postoperative period without complications. There are no complaints.

According to OCT (Fig. 8): when comparing with the previous study, a significant decrease in edema was revealed by area and volume, the thickness of the retina in the central zone was 272 μm (47 μm less), the maximum height of edema in the zone of vessel damage was 363 μm, and the macular volume amounted to 8.75 μm ³ . At discharge, Vis OS = 0.8 n / k. IOP 20 mmHg When observing the patient in the following months, the indicators of visual acuity, field of view, OCT and phage remained stable.

Thus, the proposed method improves the accuracy and objectivity of the choice of parameters of FS in the absence of adverse and allergic reactions during the test study and, thus, increase the efficiency of laser treatment of retinal diseases.

Claims (1)

The method of selecting parameters for laser treatment of retinal diseases, which consists in applying laser test Nd: YAG laser applicates to the retina in the test area, identical in thickness and pigment distribution to the area of the planned laser coagulation, and selecting the minimum parameters giving a therapeutic effect, characterized in that at first a series of ophthalmoscopically visualized laser applications is applied using a wavelength of 561 nm, a pulse duration of 100 ms, a duty cycle of 100 ms, a power of 70 to 100 mW, then There are three series of ophthalmoscopically non-visualizable laser applications, decreasing the pulse duration first by 50%, then by 90%, then simultaneously with the pulse duration reduced by 90%, reduce the power by 20%, after which optical coherence tomography of the test area is carried out immediately, and Received scans are determined by test laser applicates with minimal parameters that give a therapeutic effect.

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