Ultrastructural changes in the retina after microinvasive 25G ultrasound vitrectomy (experimental study)

Current trends in the development of vitrectomy systems, particularly vitreous cutters, focus on reducing instrument gauge while maintaining high cutting efficiency and vitreous fragmentation capacity. Pneumatic guillotine vitreous cutters have several design limitations that constrain further improvement of their functional capabilities. The use of ultrasonic energy for vitreous fragmentation represents an alternative direction in the development of vitrectomy. The emergence of microinvasive ultrasonic 25-gauge (25G) vitreous cutters creates the need for a comprehensive assessment of their effect on ultrastructure of the retina. Objective. The study investigated ultrastructural changes in the retina of rabbits after experimental microinvasive ultrasonic and pneumatic guillotine 25G vitrectomy. Material and methods. Rabbits in the main study group underwent microinvasive ultrasonic and pneumatic guillotine 25G vitrectomy. The retina was examined using electron microscopy. The data obtained in the experimental group, in which microinvasive ultrasonic vitrectomy was used, were then compared with the results of the control group, in which 25G pneumatic guillotine vitrectomy was performed. Results. On days 1 and 7, signs of retinal changes were detected in the inner nuclear layer and nerve fiber layer: vacuolization and fragmentation of neuronal cytoplasm, vacuolization of mitochondria, and elements of the rough endoplasmic reticulum. On days 14 and 30, some structural changes persisted — although the severity of the changes decreased. The nature of the changes in the experimental group was comparable with that in the control group and could be attributed not only to the identical effect of fragmentation, but also to nonspecific surgical trauma, hydrodynamic effects of fluid flow, changes associated with preparation of the material for electron microscopic examination, and individual tissue responses. Conclusion. The ultrastructural changes in the experimental group were similar in nature and severity to those observed in the control group. Therefore, microinvasive ultrasonic 25G vitrectomy can be considered a safe technology for vitreous fragmentation, with an effect on the retinal ultrastructure comparable to that of the traditional guillotine fragmentation method.