Breadth and Depth: Three-Dimensional Endoscopic Field of View: Two-Dimensional Versus Three-Dimensional Endoscopic Field of View

The use of three-dimensional endoscope in transnasal skull base surgery: A single-center experience from China

Objective

The development of skull base surgery in the past decade has been influenced by advances in visualization techniques; recently, due to such improvements, 3D endoscopes have been widely used. Herein, we address its effect for transnasal endoscopic skull base surgery.

Methods

A total of 63 patients who under endoscopic endonasal surgery (EES) with 3-D endoscope were retrospectively reviewed, including pituitary adenomas, craniopharyngiomas, meningiomas, Rathke’s cleft cysts, and chordomas. According to different lesions, transsellar approach (24 cases), transsphenoidal–transtuberculum approach (14 cases), transclival approach (6 cases), and transpterygoid approach (19 cases) were selected.

Results

Total removal of tumors was achieved in 56 patients (88.9%) and subtotal removal in 7 cases (11.1%). Complications included diabetes insipidus in seven patients (11.1%), cerebrospinal fluid (CSF) leakage in two patients (3.2%), major vascular injury occurred in one patient (1.6%), cranial nerve injury in nine patients (14.3%), and meningitis in two patients (3.2%). There was no mortality in the series. All patients recovered and were back to normal daily life, and no tumor recurrence or delayed CSF leakage was detected during the follow-up (2–13 months, mean 7.59 months).

Conclusions

Via 3D EES, it improved depth perception and preserved important neurovascular tissue when tumors were removed, which is important for improving the operative prognosis.

Video Learning of Surgical Procedures: A Randomized Comparison of Microscopic, 2- and 3-Dimensional Endoscopic Ear Surgery Techniques

BACKGROUND

Video learning of surgical procedures helps trainees gain an initial understanding of the complex anatomy and the surgical procedure. Because no comparative studies have yet examined which microsurgical approach to the middle ear is most suitable for video learning, the authors investigated objective and subjective outcomes for medical trainees observing microscopic, 2-dimensional (2D) endoscopic, and 3- dimensional (3D) endoscopic ear surgeries.

METHODS

Sixty-two medical students (min. 3rd year) from the University Hospital of Bern watched three standardized videos of a type I tympanoplasty surgery recording, conducted with a microscope, a 2D endoscope, and a 3D endoscope, respectively. The authors measured participants' learning outcome, eye movements, cognitive load, and subjective preferences.

RESULTS

Of the 62 participants included in the study, 14 were male (22.58%), and mean age was 24.44 years (range: 21-29). Learning outcome was highest after watching the 3D endoscopic video (mean [SD], 59.48% [20.57%]). Differences in score were statistically significant: 2D endoscopic video (mean difference: -6.56%, 95% CI: -13.02 to -0.10%), microscopic video (mean difference: -13.82%, 95% CI: -20.27 to -7.36%). Participants showed lowest average eye fixation duration when watching the 3D endoscopic video (mean [SD], 307 ms [109 ms]), with statistically significant differences to the 2D endoscopic video (mean difference: -139 ms, 95% CI: -185 to -93 ms), and the microscopic video (mean difference: -264 ms, 95% CI: -310 to -218 ms). Participants reported lowest cognitive load for the 2D and 3D endoscopic videos. Ratings on discomfort, usability, naturalness, depth perception, and image quality were in favor of the 3D endoscopic video.

CONCLUSION

The 3D endoscopic technique offers many advantages for video learning in terms of knowledge gain, visual field exploration, and subjective evaluation. To optimize learning effects in trainees, the authors recommend the use of endoscopes in middle ear surgery and, if available, using 3D technology.

High sensitivity curvature sensor based on the long period fiber grating inscribed in the two-mode fiber

The optical fiber curvature sensor is an important device that is widely used in the field of medical instruments. In this paper, we proposed a high sensitivity curvature sensor based on a long period fiber grating (LPFG), which is inscribed in the two-mode fiber (TMF) by CO₂ laser pulses. Unlike the traditional LPFG in the single-mode fiber, TMF-LPFG couples the high-order mode LP₁₁ in the core with the modes in the cladding. From the experiment results, the wavelength shifts to the short-wave direction as the sensor bends. This sensor offers a high curvature sensitivity of -23.67nm/m^-1 in the range of 1.137-4.684m^-1 and -18.95nm/m^-1 in the range of 4.766-6.132m^-1, respectively. Moreover, this sensor has the advantage of low transmission loss, which is less than -4dB.