Telementoring in Leg Fasciotomies via Mixed-Reality: Clinical Evaluation of the STAR Platform.

INTRODUCTION: Point-of-injury (POI) care requires immediate specialized assistance but delays and expertise lapses can lead to complications. In such scenarios, telementoring can benefit health practitioners by transmitting guidance from remote specialists. However, current telementoring systems are not appropriate for POI care. This article clinically evaluates our System for Telementoring with Augmented Reality (STAR), a novel telementoring system based on an augmented reality head-mounted display. The system is portable, self-contained, and displays virtual surgical guidance onto the operating field. These capabilities can facilitate telementoring in POI scenarios while mitigating limitations of conventional telementoring systems. METHODS: Twenty participants performed leg fasciotomies on cadaveric specimens under either one of two experimental conditions: telementoring using STAR; or without telementoring but reviewing the procedure beforehand. An expert surgeon evaluated the participants' performance in terms of completion time, number of errors, and procedure-related scores. Additional metrics included a self-reported confidence score and postexperiment questionnaires. RESULTS: STAR effectively delivered surgical guidance to nonspecialist health practitioners: participants using STAR performed fewer errors and obtained higher procedure-related scores. CONCLUSIONS: This work validates STAR as a viable surgical telementoring platform, which could be further explored to aid in scenarios where life-saving care must be delivered in a prehospital setting.

Augmented Reality as a Medium for Improved Telementoring.

Combat trauma injuries require urgent and specialized care. When patient evacuation is infeasible, critical life-saving care must be given at the point of injury in real-time and under austere conditions associated to forward operating bases. Surgical telementoring allows local generalists to receive remote instruction from specialists thousands of miles away. However, current telementoring systems have limited annotation capabilities and lack of direct visualization of the future result of the surgical actions by the specialist. The System for Telementoring with Augmented Reality (STAR) is a surgical telementoring platform that improves the transfer of medical expertise by integrating a full-size interaction table for mentors to create graphical annotations, with augmented reality (AR) devices to display surgical annotations directly onto the generalist's field of view. Along with the explanation of the system's features, this paper provides results of user studies that validate STAR as a comprehensive AR surgical telementoring platform. In addition, potential future applications of STAR are discussed, which are desired features that state-of-the-art AR medical telementoring platforms should have when combat trauma scenarios are in the spotlight of such technologies.

An Augmented Reality-Based Approach for Surgical Telementoring in Austere Environments.

Telementoring can improve treatment of combat trauma injuries by connecting remote experienced surgeons with local less-experienced surgeons in an austere environment. Current surgical telementoring systems force the local surgeon to regularly shift focus away from the operating field to receive expert guidance, which can lead to surgery delays or even errors. The System for Telementoring with Augmented Reality (STAR) integrates expert-created annotations directly into the local surgeon's field of view. The local surgeon views the operating field by looking at a tablet display suspended between the patient and the surgeon that captures video of the surgical field. The remote surgeon remotely adds graphical annotations to the video. The annotations are sent back and displayed to the local surgeon while being automatically anchored to the operating field elements they describe. A technical evaluation demonstrates that STAR robustly anchors annotations despite tablet repositioning and occlusions. In a user study, participants used either STAR or a conventional telementoring system to precisely mark locations on a surgical simulator under a remote surgeon's guidance. Participants who used STAR completed the task with fewer focus shifts and with greater accuracy. The STAR reduces the local surgeon's need to shift attention during surgery, allowing him or her to continuously work while looking "through" the tablet screen.

Femtosecond laser capsulotomy.

PURPOSE: To evaluate a femtosecond laser system to create the capsulotomy. SETTING: Porcine and cadaver eye studies were performed at OptiMedica Corp., Santa Clara, California, USA; the human trial was performed at the Centro Laser, Santo Domingo, Dominican Republic. DESIGN: Experimental and clinical study. METHODS: Capsulotomies performed by an optical coherence tomography-guided femtosecond laser were evaluated in porcine and human cadaver eyes. Subsequently, the procedure was performed in 39 patients as part of a prospective randomized study of femtosecond laser-assisted cataract surgery. The accuracy of the capsulotomy size, shape, and centration were quantified and capsulotomy strength was assessed in the porcine eyes. RESULTS: Laser-created capsulotomies were significantly more precise in size and shape than manually created capsulorhexes. In the patient eyes, the deviation from the intended diameter of the resected capsule disk was 29 µm ± 26 (SD) for the laser technique and 337 ± 258 µm for the manual technique. The mean deviation from circularity was 6% and 20%, respectively. The center of the laser capsulotomies was within 77 ± 47 µm of the intended position. All capsulotomies were complete, with no radial nicks or tears. The strength of laser capsulotomies (porcine subgroup) decreased with increasing pulse energy: 152 ± 21 mN for 3 µJ, 121 ± 16 mN for 6 µJ, and 113 ± 23 mN for 10 µJ. The strength of the manual capsulorhexes was 65 ± 21 mN. CONCLUSION: The femtosecond laser produced capsulotomies that were more precise, accurate, reproducible, and stronger than those created with the conventional manual technique.

Selective retinal therapy with microsecond exposures using a continuous line scanning laser.

PURPOSE: To evaluate the safety, selectivity, and healing of retinal lesions created using a continuous line scanning laser. METHODS: A 532-nm Nd:YAG laser (PASCAL) with retinal beam diameters of 40 µm and 66 µm was applied to 60 eyes of 30 Dutch-belted rabbits. Retinal exposure duration varied from 15 µs to 60 µs. Lesions were acutely assessed by ophthalmoscopy and fluorescein angiography. Retinal pigment epithelial (RPE) flatmounts were evaluated with live-dead fluorescent assay. Histological analysis was performed at 7 time points from 1 hour to 2 months. RESULTS: The ratios of the threshold of rupture and of ophthalmoscopic visibility to fluorescein angiography visibility (measures of safety and selectivity) increased with decreasing duration and beam diameter. Fluorescein angiography and live-dead fluorescent assay yielded similar thresholds of RPE damage. Above the ophthalmoscopic visibility threshold, histology showed focal RPE damage and photoreceptor loss at 1 day, without inner retinal effects. By 1 week, photoreceptor and RPE continuity was restored. By 1 month, photoreceptors appeared normal. CONCLUSION: : Retinal therapy with a fast scanning continuous laser achieves selective targeting of the RPE and, at higher power, of the photoreceptors without permanent scarring or inner retinal damage. Continuous scanning laser can treat large retinal areas within standard eye fixation time.

Femtosecond laser-assisted cataract surgery with integrated optical coherence tomography.

About one-third of people in the developed world will undergo cataract surgery in their lifetime. Although marked improvements in surgical technique have occurred since the development of the current approach to lens replacement in the late 1960s and early 1970s, some critical steps of the procedure can still only be executed with limited precision. Current practice requires manual formation of an opening in the anterior lens capsule, fragmentation and evacuation of the lens tissue with an ultrasound probe, and implantation of a plastic intraocular lens into the remaining capsular bag. The size, shape, and position of the anterior capsular opening (one of the most critical steps in the procedure) are controlled by freehand pulling and tearing of the capsular tissue. Here, we report a technique that improves the precision and reproducibility of cataract surgery by performing anterior capsulotomy, lens segmentation, and corneal incisions with a femtosecond laser. The placement of the cuts was determined by imaging the anterior segment of the eye with integrated optical coherence tomography. Femtosecond laser produced continuous anterior capsular incisions, which were twice as strong and more than five times as precise in size and shape than manual capsulorhexis. Lens segmentation and softening simplified its emulsification and removal, decreasing the perceived cataract hardness by two grades. Three-dimensional cutting of the cornea guided by diagnostic imaging creates multiplanar self-sealing incisions and allows exact placement of the limbal relaxing incisions, potentially increasing the safety and performance of cataract surgery.

Patterned laser trabeculoplasty.

BACKGROUND AND OBJECTIVE: A novel computer-guided laser treatment for open-angle glaucoma, called patterned laser trabeculoplasty, and its preliminary clinical evaluation is described. PATIENTS AND METHODS: Forty-seven eyes of 25 patients with open-angle glaucoma received 532-nm laser treatment with 100-µm spots. Power was titrated for trabecular meshwork blanching at 10 ms and sub-visible treatment was applied with 5-ms pulses. The arc patterns of 66 spots rotated automatically after each laser application so that the new pattern was applied at an untreated position. RESULTS: Approximately 1,100 laser spots were placed per eye in 16 steps, covering 360° of trabecular meshwork. The intraocular pressure decreased from the pretreatment level of 21.9 ± 4.1 to 16.0 ± 2.3 mm Hg at 1 month (n = 41) and remained stable around 15.5 ± 2.7 mm Hg during 6 months of follow-up (n = 30). CONCLUSION: Patterned laser trabeculoplasty provides rapid, precise, and minimally traumatic (sub-visible) computer-guided treatment with exact abutment of the patterns, exhibiting a 24% reduction in intraocular pressure during 6 months of follow-up (P < .01).

Effect of pulse duration on size and character of the lesion in retinal photocoagulation.

OBJECTIVE: To systematically evaluate the effects of laser beam size, power, and pulse duration of 1 to 100 milliseconds on the characteristics of ophthalmoscopically visible retinal coagulation lesions. METHODS: A 532-nm Nd:YAG laser was used to irradiate 36 retinas in Dutch Belt rabbits with retinal beam sizes of 66, 132, and 330 mum. Lesions were clinically graded 1 minute after placement, their size measured by digital imaging, and their depth assessed histologically at different time points. RESULTS: Retinal lesion size increased linearly with laser power and logarithmically with pulse duration. The width of the therapeutic window, defined by the ratio of the threshold power for producing a rupture to that of a mild coagulation, decreased with decreasing pulse durations. For 132- and 330-mum retinal beam sizes, the therapeutic window declined from 3.9 to 3.0 and 5.4 to 3.7, respectively, as pulse duration decreased from 100 to 20 ms. At pulse durations of 1 millisecond, the therapeutic window decreased to unity, at which point rupture and a mild lesion were equally likely to occur. CONCLUSIONS: At shorter pulse durations, the width and axial extent of the retinal lesions are smaller and less dependent on variations in laser power than at longer durations. The width of the therapeutic window, a measure of relative safety, increases with the beam size. CLINICAL RELEVANCE: Pulse durations of approximately 20 milliseconds represent an optimal compromise between the favorable impact of speed, higher spatial localization, and reduced collateral damage on one hand, and sufficient width of the therapeutic window (> 3) on the other.

[General practitioners' evaluation of the out-of-hours service in Copenhagen County]. / De praktiserende laegers vurdering af laegevagten i Københavns Amt.

INTRODUCTION: This investigation was part of a large project concerning quality development in the primary care out-of-hours service in Copenhagen County, Denmark. MATERIALS AND METHODS: In August 2003 a questionnaire was sent out to all the general practitioners in Copenhagen County (n = 365, return rate: 82%). 56% of the GPs were not working in the out-of-hours service. RESULTS: In total, 95% of those surveyed felt that the out-of-hours service is doing a good job; 95% expressed satisfaction with the professional level; and only 3% found that they did not have good cooperation with the service. 63% did not agree with the statement that the out-of-hours service is used only in acute cases of disease or acute deterioration of disease. DISCUSSION: Overall, the GPs expressed a high level of satisfaction with the out-of-hours service. They also felt that their patients were satisfied. However, the study pointed out the difference in perception between patients and doctors regarding the aim of the service.

System for the automated photothermal treatment of cutaneous vascular lesions.

It is well known that the use of tightly focused continuous wave lasers can be an effective treatment of common telangiactasia. In general, the technique requires the skills of a highly dexterous surgeon using the aid of optical magnification. Due to the nature of this approach, it has proven to be largely impractical. To overcome this, we have developed an automated system that alleviates the strain on the user associated with the manual tracing method. The device makes use of high contrast illumination, simple monochromatic imaging, and machine vision to determine the location of blood vessels in the area of interest. The vessel coordinates are then used as input to a two-dimensional laser scanner via a near real-time feedback loop to target, track, and treat. Such mechanization should result in increased overall treatment success, and decreased patient morbidity. Additionally, this approach enables the use of laser systems that are considerably smaller than those currently used, and consequently the potential for significant cost savings. Here we present an overview of a proof-of-principle system, and results using examples involving in vivo imaging of human skin.