Purpose: to evaluate the morphological changes in eye tissue after the influence of high‐frequency electric current welding (HFECW) with suprachoroidal approach in rabbit's eyes in order to induce chorio‐retinal adhesion as an alternative treatment for retinal tears. Methods: 54 adult rabbits were used. The study complied to the ARVO statement for use of animals in ophthalmic and visual research. In the treated group, the retina was coagulated 7–10 mm from the limbus through a U‐shaped scleral incision with suprachoroidal approach using 23‐gauge tip and modified HFECW generator EK‐300 M1 (E.O. Paton Electric Welding Institute, Kyiv, Ukraine) with parameters: 66 kHz HFECW, three modes of 10–12 Volts (V), 12–14 V and 14–16 V. The eyes were then enucleated after 1 hour and 3‐, 7‐, 14‐ and 30‐days. Tissue changes were analysed using haematoxylin–eosin staining and light microscopy, and compared to the control eyes. Results: In all treated eyes the monopolar HFECW induced an increased tissue adhesion in the area of electrode application, which strengthened with time. The retina responded by apparent destruction of rods, cones, loss of bipolar, amacrine, horizontal and ganglion cells, development of cysts and migration of RPEs. The choroid showed damage and migration of melanocytes. By 30 days, a ​​tissue thinning with partial cell regeneration and connective tissue degeneration were apparent. Amplification of the voltage from 10 to 16 V caused a shift from active exudation without significant tissue damage to acute retinal necrosis, respectively. The nearby lying retinal layers and vitreous remained intact. Conclusions: Application of HFECW with suprachoroidal approach induced chorio‐retinal adhesion in 1 hour after the treatment, which strengthened within first weeks after the surgery. Implementation of HFECW as an alternative method to treat retinal tears in eyes with retinal detachment could reduce the need for endotamponade and the risks of its possible complications.

Retinal detachment (RD), its rupture, concussion, hemorrhage require urgent ophthalmic surgical intervention without fail. Restoring the anatomical integrity of the detached retina, the speed of surgical intervention, the choice of access and method of surgery, the quality of the surgical instrument are directly causally related to visual acuity, the number and severity of postoperative complications. The best complex ophthalmosurgical solutions relieve vitreoretinal surgeons of the need for vitrectomy and postoperative tamponade, provide sufficient strength of the chorioretinal connection, cause little oedema in the surgical site, a minimal atrophy, and a quick repair process. An important objective indicator of the optimal choice of the tool, access and nature of the intervention is minimal damage of the retina neurolayer and a decrease in its thickness due to surgical impact. This publication is devoted to the second phase of an experiment on animals, which simulates an operation to restore the anatomical integrity of a detached retina. The parameters of high-frequency monopolar electrocoagulation (current 0.1 A, voltage 10–16 V, frequency 66 kHz, suprachoroidal access, instrument of the original design with a extreme part of sphere diameter of 25 G) remain unchanged. For the second phase of the experiment, 30 adult rabbits (60 eyes) were used, divided into three experimental groups (10 animals, 20 eyes each) according to the exposure voltage (I – 10–12 V, II – 12–14 V, III – 14–16 V) and euthanized 1 week, 2 weeks and 1 month after surgery. The experiment took into account the data of its first phase regarding the control (IV) group of animals, which included 6 intact rabbits (12 eyes), as well as observations 1 hour and 3 days after the operation. The morphological structure of rabbit eyes was studied with an emphasis on the processes of oedema, atrophy and thickness of the retina. Keywords: chorioretinal surgery, experimental ophthalmic surgery, retinal detachment, retinal thickness.

Retinal detachment is a pathological condition that leads to vision loss without timely surgical treatment. To restore the anatomical integrity of the detached retina, a number of surgical interventions (Scleral Buckling, Pars Plana Vitrectomy, a combined Pars Plana Vitrectomy/Scleral Buckling, Pneumatic Retinopexy, cryo-, laser-, and electropexy) and approaches to the damaged area are traditionally used, among which one of the new and promising are monopolar high-frequency electrocoagulation with suprachoroidal access. The advantages of this method and access are the possibility of manipulations on hard-to-reach structures of the eye (choroid, outer parts of the retina and macula), to introduce medical drugs into the suprachoroidal space without side effects. To carry out such an operation, we developed (manufactured and tested) a new surgical electrical instrument capable of restoring the anatomical integrity of a detached retina. The tool is a working electrode, which consists of a handle, a terminal (for connecting the electric cord to the active phase of the high-frequency electric current generator) and a working tip. The rounded tip is made of gold and ends in a sphere with a diameter of 25 G. The radius of the round is 29.0 mm, the diameter of the cross section is 0.5 mm. The tool allows you to reach the damaged area of the retina through both suprachoroidal and endovitreal accesses. The rounded shape of the working part of the tool repeats the anatomical curvature of the fundus of the eye. The materials chosen for the manufacture of the new tool take into account the need for its sterilization, electrical safety and ergonomics of work. Keywords: retinal detachment, high-frequency electrocoagulation, electric instrument for vitreoretinal surgery.

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