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

2020 ◽  
Vol 44 (5) ◽  
pp. 809-820
Author(s):  
A.S. Shirokanev ◽  
A.S. Kibitkina ◽  
N.Y. Ilyasova ◽  
A.A. Degtyarev

When laser coagulation of eye retina is carried out, the laser beam is directed to target retinal areas selected by an ophthalmologist. The exposure to laser light produces a photocoagulate. When using laser coagulation, the main problem is selecting both the laser exposure areas that would cover all pathological zones and the laser exposure parameters to prevent retina damage. Any patient has an individual fundus structure. The individual structure of pathological and anatomical elements must be taken into account to achieve the desired therapeutic effect. The formation of coagulates in all hemorrhage-affected areas results in the desired therapeutic effect. The vascular layer must be heated to a sufficient temperature to form a coagulate. Such an effect can be predicted using mathematical modeling of laser exposure. In this paper, we consider methods of mathematical modeling of laser exposure based on the solution of a heat equation. The methods are compared in terms of their computational complexity and solution stability. An analysis of the possibility of predicting the therapeutic effect using methods of mathematical modeling of laser exposure is carried out.

2021 ◽  
Vol 24 (5) ◽  
pp. 89-101
Author(s):  
A. S. Shirokanev

Introduction. Diabetes mellitus is a common endocrine disease that can lead to retinal vascular damage caused by the spread of macular edema and the development of diabetic retinopathy. Currently, diabetic retinopathy is treated using retinal laser coagulation. However, since even modern systems do not demonstrate sufficient treatment efficacy, methods for providing laser coagulation support on the basis of patient data analysis are required.Aim. This paper aims to develop and study a method for estimating a safe distance between coagulates via the mathematical modeling of coagulation in order to provide laser coagulation support.Materials and methods. The problem of thermal conductivity is numerically modeled for laser action in a multilayer medium.Results. A method for estimating a safe distance between coagulates has been developed via the mathematical modeling of the thermal conductivity problem. An algorithm was established for reconstructing a three-dimensional fundus structure from OCT images. It was demonstrated that the convergence rate of the integro-interpolation method is higher than that of the finite difference method. The study revealed that the retina heats up to 45 ºС due to heat redistribution from the epithelial layer, as well as laser exposure. According to the study results, the developed method yields a safe distance of 180 µm. By increasing the delay between laser pulses by more than 10 ms, this distance can be reduced to 160 μm.Conclusion. The developed method can calculate distance corresponding to that used in medical practice. Besides safe distance, the use of this method will allow other laser coagulation parameters to be determined non-invasively: laser power and pulse duration recommended to achieve a therapeutic effect. These estimates can be used to automatically produce a preliminary laser coagulation plan to support diabetic retinopathy treatment.


2018 ◽  
Vol 8 (5) ◽  
pp. 1471-1482 ◽  
Author(s):  
Fei Xiong ◽  
Kunliang Liu ◽  
Sha Liu ◽  
Jianjun Chen ◽  
Jinghan Liu ◽  
...  

Author(s):  
Sergey V. BELIKOV ◽  
Andrey P. GOYDIN ◽  
Oleg L. FABRIKANTOV ◽  
Pavel L. VOLODIN

Relevance of the study . Blindness and hypovision due to retinopathy of prematurity dominate in the structure of the causes of visual impairment from childhood in both developed and developing countries, despite all the achievements of science and practical medicine. A huge role in preventing blindness from retinopathy of prematurity belongs to the effectiveness of treatment. The most discussed topic among global ophthalmology community is readings and the time of laser coagulation of the eye retina. Aim of the study . To evaluate the advantages and disadvantages of laser coagulation various methods in retinopathy of prematurity, to determine the most optimal method in the treatment of active phases of the disease. Materials and methods . We consider retinopathy of prematurity modern methods of diagnosis and treatment, also we carry out advantages and disadvantages comparative analysis. We consider the organization statistics of ophthalmic care for premature infants in the Tambov Region and the long-term treatment results of premature infants with retinopathy of prematurity. Results and discussion . The generally accepted standard methodology applied for screening examination, is the reverse binocular ophthalmoscopy (possible in humidicrib) when medication dilate pupils. If necessary, an examination is carried out using the retinal pediatric camera “RetCam Shuttle” (Clarity Medical Systems Inc., USA), which allows to document and save the survey results in a database. To date, timely and sufficient laser coagulation of the avascular zone of the retina is the only proven effective method of active retinopathy of prematurity treatment. The most modern method of retinal laser coagulation is the technology of pattern scanning laser coagulation, which automated the procedure for applying coagulants. The main trends in the retinopathy of prematurity treatment are earlier implementation of laser coagulation and over dosed coagulation, according to the ETROP recommendations. When using a pattern laser system, laser pulses are delivered in sequence at the highest speed. The result of the use of this technology is a high accuracy of coagulation, so that the eye retina receives the least energy impact, compared with the classical laser coagulation. Conclusion. 1. Timely and adequate laser coagulation of the avascular areas of the eye retina reduces the risk of severe anatomical and functional outcomes of active retinopathy of prematurity. 2. The use of the technology of transpupillary scanning pattern laser coagulation of the eye retina (PASCAL) can significantly reduce the duration of laser exposure and anesthesia for a premature baby, improve the efficiency and safety of treatment.


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