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.

Introduction. Retinal detachment (RD) is a common pathological condition that without timely surgical treatment leads to vision loss. The patients with significant RD undergo one of three retreatment procedures: Pneumatic Retinopexy, Scleral Buckling, and/or Pars Plana Vitrectomy. Techniques and tools for these procedures have been developed, but the methods themselves still have a significant number of complications. A possible alternative to their further improvement may be a fundamentally new method of treatment, coagulation of the retina with high-frequency electric current (HFEC), for which significant improvement of the tool is still possible. The purpose of the study was to determine a safer method of RD treating and to improve medical tools for restoring anatomical integrity and repositioning a detached retina under two conditions: firstly, obtaining a reliable chorioretinal adhesion, and secondly, minimizing the number of incidental effects of surgical intervention. Materials and methods. The bibliosemantic method, the system analysis method, an experiment on laboratory animals (rabbits) with RD simulation and its coagulation by HFEC, tissue biopsy of operated animals after their euthanasia on the 7th day after surgery, and the production of histological micro-preparations were used. Results. To fulfill the conditions for improving the method, a chorioretinal high-frequency electrocoagulation operation with suprachoroidal access, a modified EK-300M1 generator (Kyiv, Ukraine) with an electrode with a gold hemispherical tip of 25 gauge and electrical generation parameters of 66 kHz, 10‒16 V, 0.1 A was proposed, which causes chorioretinal adhesion in the place where the electrode is used. The method of calculating the parameters of heat transfer from the electrocoagulation tool to the tissues and fluids of the eye was selected: it was proposed to use the Fourier-Kirchhoff and Newton-Richmann equations. Destructive phenomena in the retina from the thermal effect of tissue coagulation in the form of the destruction of rods, cones, the development of cysts, the loss of bipolar, amacrine, horizontal and ganglion cells were noted. Atrophic changes in the retina were minimal at a voltage of 10‒12 V. Conclusions. The problem of improving the methods of restoring the anatomical position of the retinal layers has been relevant for many decades, but it does not lead to a significant reduction in the number of complications. The proposed method and tool for its application causes the creation of a reliable chorioretinal adhesion in a short period of time after surgical intervention with minimal thermal tissue damage. The use of the method of chorioretinal high-frequency electrocoagulation with suprachoroidal access is recommended in conditions of urgent restoration of vision, but not recommended for the prevention of retinal detachment in retinopathies. Keywords: retinal detachment, chorioretinal adhesion, high-frequency electrocoagulation, suprachoroidal access.

Retinal detachment (RD) is a condition that requires urgent ophthalmic surgery. Existing methods of RD vitreoretinal correction cause numerous complications and bring inconvenience to patients due to the need for vitrectomy and postoperative tamponade. Therefore, methods of RD surgical treatment are promising, which allow forming a strong chorioretinal adhesion in a short period of time after surgery, but damage the retina as little as possible. With this aim, in an experiment on rabbits, we studied the consequences of damage and features of retinal repair after high-frequency monopolar electrocoagulation (at a current of 0.1 A, 10–16 V and 66 kHz) by suprachoroidal access with an instrument of original design with a terminal sphere 25 G. For the experiment, 24 adult rabbits (48 eyes) were used, which were divided into three experimental groups (6 animals each, 12 eyes each) according to the exposure voltage (I – 10÷12 V, II – 12÷14 V, III – 14 ÷16 V) and one control (IV) group, which included 6 intact rabbits (12 eyes). Micropreparations obtained by us after euthanasia of animals early after surgery (after 1 hour and 3 days) showed us morphological changes in the eye tissues in places of direct contact with the electrode, remote and transitional areas. Edema processes prevailed among these changes. However, during this period, we could not investigate the processes of atrophy, which are also important for the recovery of acuity and visual fields after the recovery of RD. It was decided to monitor the animals for an additional period (until the end of the first month of the experiment), for which it will be necessary to increase the group of laboratory animals during the continuation of the experiment.