Improve Depth Perception Research Articles

Head to Head Comparison between Different 3-Dimensional Echocardiographic Rendering Tools in the Imaging of Percutaneous Edge-to-Edge Mitral Valve Repair.

MitraClip (MC) is the most common percutaneous treatment for severe mitral regurgitation (MR). An accurate two-dimensional and three-dimensional echocardiographic (3DTEE) imaging is mandatory for the optimal procedural result. Recently transillumination 3DTEE rendering (3DTr) has been introduced integrating a virtual light source into the dataset and with the addition of glass effect (3DGl) allows to adjust tissue transparency improving depth perception and anatomical structure delineation in comparison with the standard 3DTEE (3DSt). The aim of this retrospective study in 30 patients undergoing MC, was to compare 3DSt, 3DTr, and 3DGl in mitral valve (MV) evaluation and procedural result assessment. 3DTEE acquisitions obtained before and after MC were processed with 3DSt, 3DTr, and 3DGl rendering. Each reconstruction was scored for quality and for ability to recognize MV anatomy, MR origin, clip position, dimension and grasping. Imaging quality was judged good or optimal in 52%, 76%, and 96% in 3DSt, 3DTr, and 3DGl reconstructions respectively. In 26/30 patients a diagnostic incremental value was found with 3DTr vs. 3DSt and in 15/26 with 3DGl vs. 3DTr and 3DSt. Only 3DGl with perpendicular cropping of the clip allowed to visualize and measure the grasped portion of each mitral leaflets. 3DTEE imaging during MC may be improved by 3DTr and 3DGl providing a better evaluation of MV, of leaflet grasping and of residual MR jets after MC.

Dichoptic Perceptual Training and Sensory Eye Dominance Plasticity in Normal Vision

PurposeWe introduce a set of dichoptic training tasks that differ in terms of (1) the presence of external noise and (2) the visual feature implicated (motion, orientation), examining the generality of training effects between the different training and test cues and their capacity for driving changes in sensory eye dominance and stereoscopic depth perception.MethodsWe randomly assigned 116 normal-sighted observers to five groups (four training groups and one no training group). All groups completed both pre- and posttests, during which they were tested on dichoptic motion and orientation tasks under noisy and noise-free conditions, as well as a binocular phase combination task and two depth tasks to index sensory eye dominance and binocular function. Training groups received visual training on one of the four dichoptic tasks over 3 consecutive days.ResultsTraining under noise-free conditions supported generalization of learning to noise-free tasks involving an untrained feature. By contrast, there was a symmetric learning transfer between the signal-noise and no-noise tasks within the same visual feature. Further, training on all tasks reduced sensory eye dominance but did not improve depth perception.ConclusionsTraining-driven changes in sensory eye balance do not depend on the stimulus feature or whether the training entails the presence of external noise. We conjecture that dichoptic visual training acts to balance interocular suppression before or at the site of binocular combination.

Training in endoscopic ear surgery using the papaya petiole.

Endoscopic ear surgery is a game changer in the field of otology. Training in endoscopic skills is essential for ENT residents, and is especially important during the coronavirus disease 2019 lockdown period. In such difficult times, ENT residents and surgeons can undergo hands-on training using a papaya petiole, even within their homes. Endoscopic ear surgery training can be carried out using a papaya petiole, enabling the practice of grommet insertion, tympanomeatal flap elevation and foreign body removal from the external auditory canal. This model does not need any laboratory setup. The hollow structure of the papaya petiole model is very similar to that of the external auditory canal, making training in endoscopic ear surgery easy. Use of the model helps a beginner to train in endoscopic handling and microsurgical instrumentation, and improves depth perception. In addition, it does not require high-end facilities to store equipment or undertake the training at any given point in time.

Comparing Botulinum Toxin Injections with Extraocular Muscle Surgery in Toddlers with Esotropia: A Retrospective Analysis.

In toddlers with esotropia, early alignment of the visual axes either with extraocular muscle surgery (EOMS) or botulinum toxin injections (BTIs) into both medial rectus muscles may result in improved depth perception. We compared the outcome of BTIs with EOMS in toddlers in order to gain further insight into the advantages and disadvantages of either method. In this retrospective study, our encrypted database was searched for toddlers with esotropia aged 35 months or younger at the time of initial treatment with either BTIs or EOMS and who had a follow-up of at least 2 years. We analyzed the angle of deviation, dose effect (DE), and binocularity as well as the number of interventions. We identified 26 toddlers who received their first treatment for esotropia within the first 35 months of life: 16with BTIs (9 males, 7 females) and 10 with EOMS (3 males, 7 females). Mean follow-up was considerably longer in the EOMS (87.7 months) than in the BTI group (35.7 months). Age at first intervention was 22.8 months in the BTI and 24.1months in the EOMS group, and each toddler wore its full cycloplegic refraction. Mean angle at treatment was 41.25 prism diopters (PD) in the BTI compared to 52.9 PD in the EOMS group. The BTI group received an average of 1.68 BTIs, with a mean dosage of 14.5 IU Botox and a mean DE (mDE) of 1.8 PD/IU. In the EOMS group, the average number of surgeries was 1.4, with a mean dosage of 16.85 mm and a mDE of 3.14 PD/mm surgery. Some degree of binocularity could be observed in 9 (56%) of the BTI (5 × Bagolini positive, 2 × 550″, 2 × 220″) and in 4 (40%) of the EOMS group (2 × 3600″, 1 × 550″, 1 × 300″). By the end of the BTI group follow-up, four toddlers electively underwent EOMS rather than a 3rd BTI (followed by a 3rd BTI in 1), which resulted in the appearance of measurable binocularity in all four (1 × Bagolini positive, 1 × 220″, 1 × 200″, 1 × 60″). Our results show that BTIs are a viable treatment alternative in early esotropia. Even if EOMS is ultimately required, some binocularity may develop as the visual axes are aligned for some time in the sensitive phase owing to the effects of Botox. Moreover, less surgical dosage is needed than would have otherwise been necessary to treat the original angle of deviation. BTIs are faster, less invasive, and present as an effective alternative when patient compliance is too low to reliably measure the angle of deviation, which is essential for the planning of EOMS.

3D endoscopy shows enhanced anatomical details and depth perception vs 2D: a multicentre study

PurposeThe current standard endoscopic technique is a high resolution visualisation up to Full HD and even 4 K. A recent development are 3D endoscopes providing a 3-dimensional picture, which supposedly gives additional information of depth, anatomical details and orientation in the surgical field. Since the 3D-endoscopic technique is new, little scientific evidence is known whether the new technique provides advantages for the surgeon compared to the 2D-endoscopic standard technique in FESS. This study compares the standard 2D-endoscopic surgical technique with the new commercially available 3D-endoscopic technique.MethodsThe prospective randomized interventional multicenter study included a total of 80 referred patients with chronic rhinosinusitis with and without polyps without prior surgery. A bilateral FESS procedure was performed, one side with the 2D-endoscopic technique, the other side with the 3D-endoscopic technique. The time of duration was measured. Additionally, a questionnaire containing 20 items was completed by 4 different surgeons judging subjective impression of visualisation and handling.Results2D imaging was superior to 3D apart from “recognition of details”, “depth perception” and “3D effect”. For usability properties 2D was superior to 3D apart from “weight of endoscopes”. Mean duration for surgery was 26.1 min for 2D and 27.4 min. for 3D without statistical significance (P = 0.219).ConclusionThree-dimensional endoscopy features improved depth perception and recognition of anatomic details but worse overall picture quality. It is useful for teaching purposes, yet 2D techniques provide a better outcome in terms of feasibility for routine endoscopic approaches.

Accurate Image-guided (Re)Placement of NIRS Probes

Background and Objective: Functional near-infrared spectroscopy (fNIRS) has become an attractive choice to neuroscience because of its high temporal resolution, ease of use, non-invasiveness, and affordability. With the advent of wearable fNIRS technology, on-the-spot studies of brain function have become viable. However, the lack of within-subject reproducibility is one of the barriers to the full acceptability of fNIRS. To support the validation of the claim that within-subject reproducibility of fNIRS could benefit from accurate anatomical information, we present in this paper a method to develop an image-based system that improves the placement of the sensors on the scalp at interactive rates.Methods: The proposed solution consists of an electromagnetic digitizer and an interactive visualization system that allows monitoring the movements of the digitizer on a real head with respect to the underlying cerebral cortical structures. GPU-based volume raycasting rendering is applied to unveil these structures from the corresponding magnetic resonance imaging volume. Scalp and cortical surface are estimated from the scanned volume to improve depth perception. An alignment algorithm between the real and scanned heads is devised to visually feedback the position of the stylus of the digitizer. Off-screen rendering of the depthmaps of the visible surfaces makes spatial positioning of a 2D interaction pointer possible.Results: We evaluated the alignment accuracy using four to eight anatomical landmarks and found seven to be a good compromise between precision and efficiency. Next, we evaluated reproducibility in positioning five arbitrarily chosen points on three volunteers by four operators over five sessions. In every session, seven anatomical landmarks were applied in the alignment of the real and the scanned head. For the same volunteer, one-way analysis of variance (ANOVA) revealed no significant differences within the five points digitized by the same operator over five sessions (α = 0.05). In addition, preliminary study of motor cortex activation by right-hand finger tapping showed the potential of our approach to increase functional fNIRS reproducibility.Conclusions: Results of experiments suggest that the enhancement of the visualization of the location of the probes on the scalp, relative to the underlying cortical structures, improves reproducibility of fNIRS measurements. As further work, we plan to study the fNIRS reproducibility in other cortical regions and in clinical settings using the proposed system.

Gaze-Contingent Ocular Parallax Rendering for Virtual Reality

Immersive computer graphics systems strive to generate perceptually realistic user experiences. Current-generation virtual reality (VR) displays are successful in accurately rendering many perceptually important effects, including perspective, disparity, motion parallax, and other depth cues. In this article, we introduce ocular parallax rendering, a technology that accurately renders small amounts of gaze-contingent parallax capable of improving depth perception and realism in VR. Ocular parallax describes the small amounts of depth-dependent image shifts on the retina that are created as the eye rotates. The effect occurs because the centers of rotation and projection of the eye are not the same. We study the perceptual implications of ocular parallax rendering by designing and conducting a series of user experiments. Specifically, we estimate perceptual detection and discrimination thresholds for this effect and demonstrate that it is clearly visible in most VR applications. Additionally, we show that ocular parallax rendering provides an effective ordinal depth cue and it improves the impression of realistic depth in VR.

Compact vari-focal augmented reality display based on ultrathin, polarization-insensitive, and adaptive liquid crystal lens

Despite the recent advances in augmented reality (AR), which has shown the potential to significantly impact on our daily lives by offering a new way to manipulate and interact with virtual information, minimizing visual discomfort due to the vergence–accommodation conflict remains a challenge. Emerging AR technologies often exploit focus-tunable optics to address this problem. Although they demonstrated improved depth perception by enabling proper focus cues, a bulky form factor of focus–tunable optics prevents their use in the form of a pair of eyeglasses. Here, we propose a novel optical configuration for a compact vari-focal AR display which deliberately utilizes the zeroth and first diffraction orders of the LC lens to produce two foci: one for a real object and the other for a virtual object with addressable focal planes. The prototype AR glasses can adjust the accommodation distance of the virtual image, mitigating the vergence–accommodation conflict without substantially compromising the form factor or image quality. In addition, we describe the design, fabrication, and characterization of an ultrathin, polarization-insensitive focus-tunable liquid crystal (LC) diffractive lens with a large aperture, a low weight, and a low operating voltage. We show that the polarization dependence of the lens, which is an inherent optical property of LC lenses, can be insensitive using the trilayer birefringent materials and by aligning the optical axes of each birefringent material at a specific angle. The polarization insensitivity eliminates the need for a polarizer, thus further reducing the form factor of the optical system. This novel approach offers significantly reduced complexity for designing AR glasses with addressable focal planes. These technologies for ultrathin lens and AR display show promising potential for developing compact optical systems in various applications.

Shadow extension for ray casting enhances volumetric visualization in real-time 4D-OCT

Progress in swept source laser technology and graphics processing unit (GPU) have led to the realization of real time four-dimensional optical coherence tomography (4D-OCT). Various rendering algorithms have been introduced for volumetric OCT leading to enhanced spatial comprehension. These algorithms still cannot provide sufficient visual realism. Shadowing is one of the advanced rendering techniques used to provide realistic spatial comprehension for objects in space. We developed and implemented a shadow extension for ray casting for real-time 4D-OCT, using both a swept source (SS)-OCT and spectral domain (SD)-OCT. Our technique builds upon previously developed ray casting techniques, adding an additional shadowing computation. The shadow extension for ray casting yields greater three-dimensionality of objects via self-shadowing, and also improves depth perception of objects. We imaged a beveled needle hovering over a flat surface and found that the positioning of a beveled needle can be accurately determined in relation to the environment. The shadowing algorithm was implemented using texture memory of the GPU, which realized video rendering rate. The complete processing pipeline requires 47 ms with a volume size of 1024 × 256 × 100, with a 100 kHz sweep rate SS-OCT. This new algorithm may enhance interactive surgical guidance during ophthalmic microsurgery.

Three‐dimensional laparoscopic vision improves forceps motion more in the depth direction than in the horizontal direction: An analysis of data from prospective randomized controlled trials

Three-dimensional (3D) laparoscopic vision can improve depth perception. However, it is a question whether 3D vision can improve motion in the depth direction. The aim of this study was to compare the impact of 3D vision on forceps motion in the depth and horizontal directions. All data were obtained from our previous two studies, where, in total, 40 novices and 20 moderately experienced surgeons participated. A simple phantom task was performed in a training box. The participants were randomly assigned to two groups. Specifically, one group performed the task five times initially under a two-dimensional (2D) system, and the other group started under a 3D system. Both groups then performed the same task five times under the alternative system. Performances were recorded by an optical position tracker. We separately evaluated forceps motion in the x-, y-, and z-axis directions. Compared with the findings for 2D vision, the forceps path lengths were significantly decreased among novices and moderately experienced surgeons in almost all tasks under 3D vision. In a comparison of the path length ratio (3D/2D) in each direction, larger reduction was observed for the depth direction among novices, whereas no significant directional difference was noted among moderately experienced surgeons. For novices, 3D laparoscopic vision improves depth perception and may give shorter forceps movement in the depth direction even for simple tasks.

Survey on depth perception in head mounted displays: distance estimation in virtual reality, augmented reality, and mixed reality

Depth perception is one of the important elements in virtual reality (VR). The perceived depth is influenced by the head mounted displays that inevitability decreases the virtual content's depth perception. While several questions within this area are still under research; the main objective of this study is to survey the recently conducted studies on depth perception in VR, augmented reality (AR), and mixed reality (MR). First, depth perception in the human visual system is discussed including the different visual cues involved in depth perception. Second, research performed to understand and confirm depth perception issue is examined. The contributions made to improve depth perception and specifically distance perception will be discussed with their main proposed design key, advantages, and limitations. Most of the contributions were based on using one or two depth cues to improve depth perception in VR, AR, and MR.

Three-Dimensional Versus Two-Dimensional Laparoscopic-Assisted Transanal Pull-Through for Hirschsprung's Disease in Children: Preliminary Results of a Prospective Cohort Study in a Tertiary Hospital.

This prospective cohort study is aimed to compare the efficacy and safety of three-dimensional (3D) versus two-dimensional (2D) laparoscopy in laparoscopic-assisted transanal pull-through (LATP) for the surgical treatment of Hirschsprung's disease (HD) in children. This study enrolled 80 children who were histologically diagnosed with HD and undergone LATP performed by a single experienced surgeon at our department between January 2015 and November 2017. Children were randomized to receive 2D laparoscopy (n = 40) or 3D laparoscopy (n = 40). Data on patient characteristics, operative parameters, and the surgeon's assessment on utilization of laparoscopic system were prospectively recorded and analyzed. Patient characteristics, including age at surgery, gender, weight, and the level of aganglionosis, were comparable between the two groups (each P > .05). Compared with 2D imaging system, 3D system significantly shortened the performance time of laparoscopic phase (27.0 ± 3.6 minutes versus 38.3 ± 4.3 minutes, P < .001) with a 29.5% reduction, and the total time of the entire surgery (106.0 ± 19.5 minutes versus 122.1 ± 18.7 minutes, P < .001). No statistical difference was observed in terms of estimated intraoperative blood loss and intraoperative laparoscopic complications between the two groups (each P > .05). In addition, 3D system significantly improved depth perception and precision, and reduced surgical strain for the surgeon. 3D LATP is feasible and safe in the surgical treatment of HD in children. Further studies are still needed to investigate the application of 3D in both experienced and inexperienced surgeons.

A comparative study of three-dimensional high-definition and two-dimensional high-definition video systems in totally endoscopic mitral valve replacement.

Three-dimensional vision with improved depth perception and spatial orientation has already proved its superiority to the two-dimensional vision in endoscopic surgery. However, those benefits remain unidentified in cardiac surgery. For the first time, we compare performance of a three-dimensional high-definition video system with a two-dimensional high-definition video system in patients undergoing totally endoscopic mitral valve replacement. We enrolled 90 patients with mitral valve disease in a single institution, from June 2013 to June 2016. Totally endoscopic mitral valve replacement was performed by the same surgeon using either a three-dimensional high-definition (n=43) or a two-dimensional high-definition (n=47) video system with the same surgical technique. Short-term outcomes were compared between the two groups. All medical records were retrieved from a prospectively maintained database of minimally invasive cardiac surgery. All surgeries were successfully completed under totally endoscopic guidance. There were no intraoperative complications in either group. The use of three-dimensional video system reduced aortic cross-clamp time by approximately 10% (3D vs. 2D: 65.74±14.32 vs. 72.67±14.67 min, P=0.027). No significant differences were observed in cardiopulmonary bypass time, postoperative ventilation duration, length of surgical intensive care unit stay, length of hospital stay, and major complications between the two groups. There were no perioperative deaths in either group. Compared with the two-dimensional video system, the three-dimensional high-definition video system provided a better surgical experience with the same operative safety for totally endoscopic mitral valve replacement.

Improved Depth Perception of Single-view Images

In many situations, we perceive 3-D depth feeling from 2-D images. Among various depth cues, monocular depth cues make us perceive depth from single-view images. In this paper, we propose several methods to enhance monocular depth cues and improve depth perception of single-view images. The proposed methods deal with four depth cues: linear perspective, aerial perspective, focus, and shadow effects. Once we have a 2-D colour image and its corresponding depth information, we can modify its depth cues and enhance 3-D depth perception in the 2-D image. Experimental results show that the proposed methods can enhance depth perception of single-view images without any considerable visual distortions.

Initial experience with cinematic rendering for the visualization of extracardiac anatomy in complex congenital heart defects†.

Detailed anatomical information is essential for planning of surgical therapy in patients with congenital heart disease. We wanted to determine whether cinematic rendering, the novel 3-dimensional visualization technique, could help paediatric cardiac surgeons achieve better preoperative visualization of the extracardiac anatomy in patients with complex congenital heart defects. Therefore, cinematic rendering was compared to the traditional volume rendering technique by means of a questionnaire with predefined criteria. Picture sets from 20 infant patients (mean age = 17 days) were generated from computed tomography data with both the cinematic rendering and the volume rendering techniques. These were presented side by side in a digital high-resolution portfolio without labelling them. Three experienced paediatric cardiac surgeons were provided with these portfolios and a questionnaire. They were asked to evaluate the images individually in predefined categories on a 4-point Likert scale from 1 = 'fully acceptable' to 4 = 'unacceptable'. Cinematic rendering scored significantly better values on the Likert scale in 7 of 9 categories, namely 'spatial impression in general', 'depth perception', 'delineation of the atrial appendages/pulmonary veins/peripheral pulmonary arteries', 'assessability of the anterior interventricular sulcus' and 'assessability of the aortic arch branches'. Cinematic rendering is a valuable software tool, and our data suggest that it provides significantly better visualization than volume rendering. The surgeons appraised improved depth perception and delineation of structures adjacent to the heart as the most significant advantages.

Development of three-dimensional laryngostroboscopy for office-based laryngeal diagnostics and phonosurgical therapy.

To develop a three-dimensional (3D) laryngostroboscopic examination unit, compare the optic playback quality in relation to established 2D procedures, and report the first case series using 3D rigid laryngostroboscopy for diagnosis and management of laryngotracheal diseases. Laboratory study, prospective case series. The optical efficacy of newly developed rigid 3D endoscopes was examined in a laboratory setting. Diagnostic suitability was investigated in 100 subjects (50 male, 50 female) receiving 2D high-definition (HD) and 3D laryngostroboscopy. Two of the subjects subsequently underwent 3D-assisted office-based transoral phonosurgery under local anesthesia. Main outcome measures were comparative visualization of laryngotracheal pathologies, influence on preoperative planning, and evaluation of prognostic factors for the outcome of phonosurgical interventions. Three-dimensional endostroboscopic procedures were effectively optimized to establish an examination protocol for all-day clinical use. Office-based 3D laryngostroboscopy was successfully applied in subjects with normal anatomy (n = 10) and various laryngotracheal findings (n = 90). In comparison to 2D HD videolaryngostroboscopy, the 3D view offered enhanced visualization of laryngotracheal anatomy, with qualitatively improved depth perception and spatial representation. In organic pathologies, this resulted in a more precise indication of phonosurgical procedures, increased accuracy in surgical planning, facilitated office-based endoscopic surgery, and better evaluation of prognostic factors for the outcome of phonosurgical interventions. Three-dimensional laryngostroboscopy proved to increase the understanding of functional and surgical anatomy. Its application has enormous potential for improving the diagnostic value of laryngoscopy, surgical precision in laryngotracheal interventions, tissue preservation, and methods of teaching. NA Laryngoscope, 128:2823-2831, 2018.

Application of a three-dimensional video system in the training for uniportal thoracoscopic surgery.

Three-dimensional (3D) video systems offer better depth perception and are associated with improved performance during endoscopic or robotic surgery. We compared the impact of a 3D video system with a two-dimensional (2D) video system on a simulation program for uniportal thoracoscopic surgery. We launched an endoscopic simulation program for uniportal surgery using a 3D high-definition video system for training surgeons and medical students. This program included three basic surgical skills: (I) peg transfer, (II) passing a needle through a 3-mm hole, and (III) suturing on a tailor-made skin model. We evaluated the impact of 3D vision during simulation for uniportal surgery in each task. Overall, 113 trainees (85 surgeons in training and 28 medical students) who had not experienced a 3D video system were registered in the program. The three surgical simulation skills were evaluated under 2D and 3D video systems. The 3D video system allowed for shorter procedural times [92 participants (80.0%) in task 1, 102 (86.4%) in task 2, and 88 (74.6%) in task 3] and improved performance. Moreover, 65 s in task 1, 145 s in task 2, and 32 s in task 3 were shortened using the 3D video system. Post-simulation survey revealed improved depth perception (n=71, 60.2%) and handling of instruments on the uniportal surgical module (n=39, 33.1%) as advantages of the 3D video system during simulation. Sixty (50.8%) trainees were not negatively affected by the use of the 3D glasses; however, 53 (44.9%) felt eye discomfort during simulation. We concluded that the 3D video system has potential advantages, such as improved procedure time and handling of instruments, during basic simulation of uniportal surgery for surgical trainees.

Three-Dimensional Thoracoscopic Surgery for Spine Fractures: A Technical Report With First Results and Experiences.

Study Design:Technical report.Objectives:Conventional 2-dimensional (2D) video-assisted thoracoscopy (VATS) is a technical procedure mainly performed by experienced surgeons. The technique may, however, come with difficulties in hand-eye coordination and estimation of depth. Three-dimensional thoracoscopy can help overcome these difficulties by providing a stereoscopic 3D view. The objective of this study is to report the first experience and results with 3D thoracoscopy for spine surgery in trauma patients.Methods:The first 4 patients treated with anterior stabilization for traumatic spine fractures using 3D thoracoscopy in an academic hospital are described. Baseline characteristics, operative time, and blood loss were retrospectively collected. This data is compared with a cohort of patients treated in the same center with the conventional 2D technique. Additionally, the treating surgeons’ and residents’ experience with the technique is described. Surgical equipment consists of 3D compatible video monitors, a videoscope with 2 cameras, and special glasses to be worn by the personnel.Results:Four patients were successfully treated using 3D thoracoscopy. Operative time was comparable to that of the conventional 2D technique and less blood loss occurred. No per- or postoperative complications or problems occurred. Per-operative views were of very high quality and provided improved depth perception. Surgeons and residents deemed the technique helpful, especially during technically demanding aspects of the procedure.Conclusions:While a shorter learning curve, decreased surgery time, and blood loss have to be proven in future prospective studies, the first experience with 3D-VATS for spine surgery is positive, and future use in minimally invasive spine surgery seems feasible.

Who profits from three-dimensional optics in endoscopic surgery? Analysis of manual tasks under two-dimensional/three-dimensional optic vision using a pelvic trainer model.

Background:In endoscopic operations, direct binocular view, tissue sensation and depth perception get lost. It is still unclear whether the novel three-dimensional (3D) high-definition (HD) cameras are able to compensate the limited senses and how this affects the skill set of users with different endoscopic experience. This study aimed first to evaluate if the 3D technology improves depth perception, precision and space orientation as compared to conventional two-dimensional (2D) HD technology. The second aim was to determine the 3D influence on participants with different endoscopic experience.Methods:A total of 24 participants of different experience levels performed three different tasks on a pelvic trainer using the same thoracoscopic unit in 2D and 3D modes. Results were statistically analysed using Student's t-test and Pearson's product–moment correlation.Results:Across all the participants, we found that 3D optic vision significantly reduced the needed time to perform a defined difficult task in comparison to 2D. This difference was less pronounced in participants with higher experience level. Participants with eyeglasses performed slower in both 2D and 3D in comparison to participants with normal vision. Only participants with normal vision could significantly improve their completion times with 3D optic vision.Conclusions:By testing the novel generation of 3D HD cameras, we could demonstrate that the 3D optic of these systems improves depth perception and space orientation for novices and experienced users and especially inexperienced users benefit from 3D optic.

Binocular summation for reflexive eye movements.

Psychophysical studies and our own subjective experience suggest that, in natural viewing conditions (i.e., at medium to high contrasts), monocularly and binocularly viewed scenes appear very similar, with the exception of the improved depth perception provided by stereopsis. This phenomenon is usually described as a lack of binocular summation. We show here that there is an exception to this rule: Ocular following eye movements induced by the sudden motion of a large stimulus, which we recorded from three human subjects, are much larger when both eyes see the moving stimulus, than when only one eye does. We further discovered that this binocular advantage is a function of the interocular correlation between the two monocular images: It is maximal when they are identical, and reduced when the two eyes are presented with different images. This is possible only if the neurons that underlie ocular following are sensitive to binocular disparity.