POTENTIALS OF MINI-INVASIVE ENDORHINOSURGERY TAKING INTO ACCOUNT THE ACTUAL BOUNDARIES OF THE FIELD OF VIEW OF MODERN ENDOSCOPES

Abstract

One of the predetermining factors to perform minimally invasive rhinosurgery successfully is the searching for optimal surgical access areas, the choice of which at present mostly depends on the visualization capabilities of endoscopic devices. The angular vision is one of the important factors for planning and performing endonasal interventions on the anterior maxillary sinus. A large viewing angle allows surgeons to expand the potentials of minimally invasive access, reduce the need to replace endoscopes with different angles during the intervention and improve the quality of the surgical procedure. The purpose of this study was to improve the method for selecting surgical access to the maxillary sinus, taking into the optical axis and the actual size of the field of view provided by the endoscope. The simulation of the process of selecting the optimal option for access to the maxillary sinus on the basis of our own method of predicting the visualization of the lumen in the sinus was performed. To determine the actual viewing angle of the endoscope, we compared the application of the standard methodology and the approach we elaborated. 3 endoscopes with a 70° optical axis orientation were examined; the studies were performed three times. We found that the results of determining the boundaries of the field of view according to our technique and to the method of Wang Q. et al. (2017) did not differ significantly, that indicates the comparable accuracy of both methods. With the declared identical characteristics of all three endoscopes, we revealed the magnitude of the field of view differed quite significantly (by a maximum of 8.7°). Moreover, the value of the viewing angle in all samples of endoscopes tested was greater than that provided by the manufacturer for standard endoscopes (60 °). The average duration of measuring the magnitude of the field of view of the endoscope by the method we proposed took 25.3 ± 3.2 s that was significantly faster than by the method of Wang Q. et al. (2017), 83.7 ± 2.0 s P≤0.05). We should also stress on the greater convenience of carrying out examinations according to our method. When assessing the potential of the maxillary sinus visualization, it is necessary to take into account not only the individual anatomical features of a patient, but also the actual optical characteristics of endoscopes. The device we designed for determining the boundaries of the field of view of endoscopes is easy to manufacture, requires less time for testing and enables to determine the actual viewing angles of the endoscope quicker and more effectively. Actual optical characteristics of endoscopes may differ from the standards.