https://doi.org/10.31288/oftalmolzh201358388

Determination of electric current threshold parameters for high-frequency electric welding of the retina in experiment and based on two-dimensional numerical simulation depending on the intraocular contents (vitreous, perftordekalin, air)

Umanets M1, Pasyechnikova N1, Naumenko V1, Ptashchenko F2

 1SI «Filatov Institute of Eye Diseases and Tissue Therapy of Medical Sciences of Ukraine»

2 Odessa National Maritime Academy, Department of Physics and Chemistry

Introduction. High-frequency electric welding (HFEW) is used in vitreoretinal surgery for retinopexy and haemostasis. Parameters of electric current may depend on the tamponade of the vitreous cavity.

Purpose. To determine threshold parameters of the electric current of HFEW of the retina in depending on the intraocular content (vitreous, perfluorodecalin) and give reasons for preference on the basis of two-dimensional numerical simulation. 

Material and methods. 4 Chinchilla adults healthy rabbit (8 eyes) were chosen for the experiment The main group (3 rabbits, 6 eyes) — HFEW in the right eye was performed after vitrectomy with perfluorodecalin tamponade of vitreous cavity, and on the left eye — air tamponade. Control group (1 rabbit, 2 eyes) — HFEW of the retina was performed in the presence of vitreous. Numerical simulation of the electrical heating of the retina was carried out by finite element software module PDE Toolbx in the package MATLAB.

Results. In cases with perfluorodecalin or air vitreal cavity tamponade to reach the threshold coagulation retinal changes during (HFEW) it is necessary to increase the electric current voltage by 6 V, in comparison with the control. This is because the electric current passes beside the retina and the vitreous body, heating it close to the edge of electric probe (there is no current flows through perfluorodecalin or air). It can be considered the most important factor affecting the dynamics of the heating of the retina. And so, the relatively high conductivity vitreous explains the fact that a high frequency electric welding of retina occurs at lower voltages in the presence of a vitreous than with tamponade by perfluorodecalin or air. It was proved by numerical model which calculates the passage processes in the electric current in the conductors and the redistribution of heat in the tissues of the eye.

Key words: retina, high-frequency electric welding, threshold parameters of electric current, determination

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