Object: proliferative diabetic retinopathy, rhegmatogenous retinal detachment, macular hole. Purpose: improve the technique of pars plana vitrectomy in patients with vitreoretinal pathology by studying experimentally structural changes in the chorioretinal complex and intraocular bleeding time during vitrectomy with the use of irrigating solutions having different temperatures. Methods: ophthalmologic (visometry, slit lamp biomicroscopy, fundus ophthalmoscopy), optical and electron microscopy, contact thermometry, statistical analysis. The temperature was monitored using a thermoelectric device which consists of hardware and software complex of temperature registration (TRITON 9004ТС-А), a measuring polytetrafluoroethylene probe of 23 Ga in diameter made on the basis of L-type thermocouples and computer with software for visualization and registration of temperature indices in real-time. Operation mode designed by the Institute of Thermoelectricity of the NAS of Ukraine and MES of Ukraine under the cooperation agreement with SI «The Filatov Institute of Eye Diseases and Tissue Therapy of the NAMS of Ukraine». Cooling of irrigation solution was performed using cold accumulators cooled to the required temperature. The experimental part 200 eyes (100 rabbits). In vivo experiment in rabbits showed that hypothermia levels during vitrectomy depended on the temperature of the solution used for vitreous cavity irrigation. In addition, in vivo experiment demonstrated that irrigation solution of 5° С or 22° С used in vitreoretinal surgery resulted in a drop of intraocular temperature to deep hypothermia levels while the use of 36° С irrigation solution during vitrectomy resulted in a decrease in temperature to mild hypothermia levels. When using irrigation solution of 5° С, 22° С and 36° С, the mean midvitreous cavity temperature decreased to 10.9° С, 25.8° С and 36.4° С, respectively. Rates of structural changes in the rabbit chorioretinal complex after long-term vitrectomy depend on the temperature of irrigation solution used during vitrectomy as well as on the duration of vitreous cavity irrigation. Vitrectomy with continuous cooling of the rabbit vitreous cavity using solutions with the temperature of 5° С, unlike those with the temperature of 22° С and 36° С, resulted in postoperative changes in the structure of the retina in a form of uneven edema in both the inner and outer retinal layers as well as in destructive changes in the inner retinal layers, based on light and electron microscopy. In a rabbit model of intraocular bleeding, use of irrigation solution of 36° С (i.e., conditions of mild hypothermia) resulted in shorter intraocular bleeding during the vitrectomy compared to the standard use of irrigation solutions (22° С). Experiments were followed by clinical studies on the effect of the irrigation solution temperature on the mean midvitreous cavity temperature in patients during vitrectomy. Taking into the account the fact that intraocular temperature in rabbits differs from that in the human eye, local hypothermia in patients was induced by irrigation solutions of 34° С (for creating the conditions of mild hypothermia), 24° С (as standard operation theater conditions), and 10° С (for creating the conditions of deep hypothermia). At the present, standard vitreoretinal surgery is performed under conditions of artificial uncontrolled local hypothermia with room-temperature irrigation solutions used during vitrectomy and with no temperature monitoring. It was found that after vitrectomy using 34° С, 24° С and 10° С irrigation solutions, there was a drop in the midvitreous cavity temperature to 1.09° С, 3.58° С and 9.33° С, respectively. There was a rise in the temperature of the midvitreous cavity temperature after completion of irrigation. Thus, the growth rate of the midvitreous cavity temperature was 0.23° С/min, 0.31° С/min and 0.21° С/min for irrigation solution with the temperature of 34° С, 24° С and 10° С, respectively. The effect of the irrigation solution temperature on the duration of intraocular bleeding and structure of the chorioretinal complex in experiment and on the intraocular fluid temperature in patients and its high recovery rates was found to be significant, which substantiates the relevance of monitoring the temperature of the irrigation solution and avoiding the use of low-temperature solutions during continuous pars plana vitrectomy. The results of the work were introduced into the practice of a clinical highly specialized center of eye microsurgery with a block of eye trauma and acute pathology of the visual organs of the Municipal Non-Profit Organization «Vinnitsa Regional Clinical Hospital named after M. I. Pirogov» of the Vinnytsia Regional Council; and the surgical department № 2 full-time subdivision of the Municipal Non-Profit Organization «Starobilsk District Territorial Medical Association» of the Starobilsk District Council. Scope – medicine, ophthalmology.
