Methods of mathematical modeling of fundus laser exposure for therapeutic effect evaluation

Shirokanev, A. S.; Kibitkina, A. S.; Ilyasova, Nataly; Degtyarev, A. A.

doi:10.18287/2412-6179-co-760

Cited by 7 publications

(4 citation statements)

References 10 publications

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“…Для минимизации повреждения фоторецепторов сетчатки необходимо снижать интенсивность лазерного воздействия, но это приведет к снижению эффективности лечения из-за недостаточного угнетения выработки VEGF и стимулирования продукции PEDF [5]. В то же время коагуляция сверх необходимой не даст пропорциональной прибавки площади термоактивированной сетчатки и приведет к преобладанию повреждающего эффекта над терапевтическим [7].…”

Section: актуальностьunclassified

“…Необходимый баланс между количеством коагулируемой и термоактивированной ткани сетчатки, а следовательно, баланс между VEGF и PEDF, будет соблюдаться в случае нанесения коагулятов, оптимальных как по интенсивности, так и по расположению [7].…”

Section: актуальностьunclassified

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Comparative quantitative assessment of the placement and intensity of laser spots for treating diabetic macular edema

Zamytskiy¹,

Золотарев²,

Карлова³

et al. 2021

Russian Journal of Clinical Ophthalmology

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Aim: to compare the uniformity and adequacy of the placement of laser spots after mono-impulse and pattern photocoagulation for diabetic macular edema (DME). Patients and Methods: fundus photographs of 83 patients (121 eyes) taken right after retinal photocoagulation for DME were analyzed. Group 1 included images of 63 eyes after pattern photocoagulation and group 2 included images of 58 eyes after mono-impulse photocoagulation. Laser burns of varying intensity based on LʹEsperance scale (including grade 0 burns that were not seen on fundus photos) were calculated. Grade 2 burns were considered optimal. The number of non-optimal laser burns placed on retinal hemorrhages, blood vessels, hard exudates or healthy retina was calculated. The uniformity of the position of laser spots was assessed by calculating the standard deviation from the average distance between laser spots. Results: the percentage of laser spots of optimal intensity was 31.85% in group 1 and 25.15% in group 2. The percentage of non-optimally placed laser spots was 24.34% in group 1 and 7.99% in group 2. The uniformity of the placement was good in both groups (8.16 pixels and 8.44 pixels, respectively), no significant difference was reported (p=0.0591). Conclusion: pattern photocoagulation is preferable for DME compared to mono-impulse photocoagulation to provide adequate intensity of laser burns. Meanwhile, mono-impulse regimen provides more precise placement of laser spots. However, both conventional techniques are not effective enough due many intrinsic drawback, i.e., many laser spots are non-optimal in terms of intensity or placement. In routine practice, these drawbacks are outweighed by the skills and experience of laser surgeon. Planned precise placement of laser spots and the introduction of techniques of more precise preventive adjustment of energy level for each laser spot will contribute to the maximum effect of photocoagulation for DME. Further studies on personalized precise laser photocoagulation will improve the quality and efficacy of the treatment of macular edema. Keywords: diabetic retinopathy, diabetic macular edema, mono-impulse photocoagulation, pattern photocoagulation, navigated photocoagulation. For citation: Zamytskiy E.A., Zolotarev A.V., Karlova E.V. et al. Comparative quantitative assessment of the placement and intensity of laser spots for treating diabetic macular edema. Russian Journal of Clinical Ophthalmology. 2021;21(2):58–62. DOI: 10.32364/2311-7729- 2021-21-2-58-62.

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Section: актуальностьunclassified

Comparative quantitative assessment of the placement and intensity of laser spots for treating diabetic macular edema

Zamytskiy¹,

Золотарев²,

Карлова³

et al. 2021

Russian Journal of Clinical Ophthalmology

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“…For this purpose, various algorithms for pattern recognition, object detection, and image segmentation [8][9][10][11] can be used. To cope with the second problem, mathematical modeling has been proposed to specify the laser exposure parameters [12]. Indeed, on the one hand, it is necessary to achieve a predetermined temperature in the area of a diabetic macular edema for the formation of a coagulum.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Fundus Laser Exposure for Estimating Safe Laser Coagulation Parameters in the Treatment of Diabetic Retinopathy

et al. 2021

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A personalized medical approach can make diabetic retinopathy treatment more effective. To select effective methods of treatment, deep analysis and diagnostic data of a patient’s fundus are required. For this purpose, flat optical coherence tomography images are used to restore the three-dimensional structure of the fundus. Heat propagation through this structure is simulated via numerical methods. The article proposes algorithms for smooth segmentation of the retina for 3D model reconstruction and mathematical modeling of laser exposure while considering various parameters. The experiment was based on a two-fold improvement in the number of intervals and the calculation of the root mean square deviation between the modeled temperature values and the corresponding coordinates shown for the convergence of the integro-interpolation method (balance method). By doubling the number of intervals for a specific spatial or temporal coordinate, a decrease in the root mean square deviation takes place between the simulated temperature values by a factor of 1.7–5.9. This modeling allows us to estimate the basic parameters required for the actual practice of diabetic retinopathy treatment while optimizing for efficiency and safety. Mathematical modeling is used to estimate retina heating caused by the spread of heat from the vascular layer, where the temperature rose to 45 °C in 0.2 ms. It was identified that the formation of two coagulates is possible when they are located at least 180 μm from each other. Moreover, the distance can be reduced to 160 μm with a 15 ms delay between imaging.

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“…Thus, it eliminates the tedious and complex process of finding the optimum incident angle by graphing method and makes the formula method the most straightforward choice for finding the optimum incident angle. This method of determining the optimal incident angle is expected to be used to evaluate the optimal laser exposure angle position [16,17]. The structure of this paper is as follows: In the second section, we analyze the modulation effect of the thickness of the parallel plate behind the wedge cavity on the spatial light intensity distribution and theoretically analyze the influence of the parallel plate on the value of the optimum incident angle.…”

Section: Introductionmentioning

confidence: 99%

A Convenient Way to Determine the Optimum Angle of Incidence of Fizeau Interferometer

Zheng

Lin

et al. 2021

Applied Sciences

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In a Fizeau interferometer, off-axis illumination will lead to fringe optimization. Primarily due to the unique structure of our interferometer, we first analyze the influence of the optical properties of the parallel plate as a part of the interferometer on the optimal incident angle. Generally, the incident angle determination is mainly based on the graphing method proposed by Langenbeck and the estimation formula proposed by Kajava. However, Langenbeck’s method is cumbersome, and the error of Kajava’s estimation formula is large. Based on the predecessors, this paper proposes a modified method of determining the optimal angle of incidence and further derives more accurate optimal angle expressions than Kajava’s. By simply substituting the wedge angle of the wedge cavity and the reflectivity of the cavity, the optimum incidence angle can be obtained immediately. Thus, it eliminates the tedious and complex process of finding the optimum incident angle by graphing method and makes the formula method the simplest method to find the optimum incident angle. Finally, the comparison of the interference intensity at the optimum incidence angle calculated by the improved method and normal incidence is given. It is found that the beam has a good suppression effect on the sub-peak when it is incident at the optimum incident angle calculated by the method in this paper.

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Methods of mathematical modeling of fundus laser exposure for therapeutic effect evaluation

Cited by 7 publications

References 10 publications

Comparative quantitative assessment of the placement and intensity of laser spots for treating diabetic macular edema

Comparative quantitative assessment of the placement and intensity of laser spots for treating diabetic macular edema

Modeling of Fundus Laser Exposure for Estimating Safe Laser Coagulation Parameters in the Treatment of Diabetic Retinopathy

A Convenient Way to Determine the Optimum Angle of Incidence of Fizeau Interferometer

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