Elsevier

The Lancet

Volume 351, Issue 9098, 24 January 1998, Pages 248-251
The Lancet

Articles
Randomised study of influence of two-dimensional versus three-dimensional imaging on performance of laparoscopic cholecystectomy

https://doi.org/10.1016/S0140-6736(97)08005-7Get rights and content

Summary

Background

Several three-dimensional video-endoscopic systems have been introduced to enhance depth perception during minimum-access surgery. However, there is no conclusive evidence of benefit, and these systems are more expensive than conventional two-dimensional systems. We undertook a prospective randomised comparison of two-dimensional and three-dimensional imaging in elective laparoscopic cholecystectomy for symptomatic gallstone disease.

Methods

The operations were done by four specialist registrars as part of their higher surgical training. 60 operations were randomised for execution by either two-dimensional or three-dimensional imaging display (30 by each method). The degree of difficulty of the operation was graded by a consultant surgeon on a standard grading system. The primary endpoints were execution time and the errors made during the procedure. The secondary endpoints were subjective assessment of the image quality and adverse effects on the surgeon.

Findings

There was no difference between the two-dimensional and three-dimensional display groups in median execution time (3160 [IQR 2735–4335 vs 3100 [2379–3710] s; p=0·2) or error rate (six vs six). Surgeons reported adverse symptoms immediately after the operations with both systems. The scores for visual strain, headache, and facial discomfort were higher with the three-dimensional system.

Interpretation

With the current technology, three-dimensional systems based on sequential imaging show no advantage over two-dimensional systems in the conduct of laparoscopic cholecystectomy.

Introduction

In minimum-access surgery (MAS), the image-display system is the visual interface between the surgeon and the operative field. Conventional video-endoscopic systems provide the surgeon with a two-dimensional magnified image at a much lower resolution than that of human eye. For controlled endoscopic manipulations, the surgeon has to reconstruct a three-dimensional picture from a two-dimensional image and to adjust the speed of instrument movement with the degree of magnification. This adjustment entails intense perceptual and mental processing, which has to be sustained throughout the operation. These limitations of current image-display systems help to explain the poorer task performance in MAS than with direct normal vision.1, 2

During the past 5 years, three-dimensional imaging systems have been introduced in an attempt to improve depth perception during MAS. Most are based on rapid sequential imaging, alternating between the two eyes by means of optical shutters (active or passive), thus presenting two slightly different images in an alternating sequence to each of the eyes separated by a few milliseconds. This arrangement differs from normal stereoscopic vision, which entails coinstantaneous images on each retina with the image falling on different sectors of the two retinas (retinal disparity), eyeball convergence, accommodation, and input from the vestibular system.

Several reports and reviews have suggested that the three-dimensional systems improve task efficiency in endoscopic manipulations,3, 4, 5, 6 whereas other studies found no difference between three-dimensional and two-dimensional systems.7 The reported benefit in clinical practice has been based on subjective impression rather than objective data and there have been no randomised studies.4, 5, 6 We have addressed this issue by a prospective randomised comparison of two-dimensional and three-dimensional imaging during elective laparoscopic cholecystectomy.

Section snippets

Methods

The patients recruited for the study had symptomatic gallstone disease and were admitted to the Professorial Unit at Ninewells Hospital for elective laparoscopic cholecystectomy. Patients who had acute cholecystitis or who had undergone major upper abdominal surgery previously were excluded from the study (figure).

Four specialist registrars carried out the operations as part of the usual supervised higher surgical training programme. Before the trial, each participating registrar had done at

Results

The two groups of patients were similar in terms of age (mean 52 years [range 27–87] for two-dimensional group vs 58 years [30–77] for three-dimensional group) and sex (eight men, 22 women vs seven men, 23 women). The operations were rated as difficulty grade 1 in 11 patients in the two-dimensional group and 13 in the three-dimensional group; grade 2 in nine and ten, respectively; and grade 3 in ten and seven, respectively.

The execution times for the component tasks and the entire operation did

Discussion

We found that the performance of laparoscopic cholecystectomy is not affected by use of three-dimensional imaging rather than conventional two-dimensional systems. This finding can be explained by the nature of the surgical task, the limitations of stereoscopy in visual displays, and by surgeon-related factors such as structured endoscopic training, experience in open surgery and MAS, and adaptation to two-dimensional imaging.

The operative field has many monocular depth cues, such as

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