Intraluminal magnetisation of bowel by ferromagnetic particles for retraction and manipulation by magnetic probes.

Feasibility studies are needed to demonstrate that safe and effective manipulation of bowel during Minimal Access Surgery (MAS) can be obtained by use of magnetic force. This paper characterises two classes of magnetic particles: stainless steel microparticles (SS-µPs) and iron oxide nanoparticles (IO-nPs) in terms of their magnetisation, chemical composition, crystallinity, morphology and size distribution. Both magnetic particles were dispersed in a high viscosity biological liquid for intraluminal injection of bowel. Ex vivo porcine bowel segments were then retracted by permanent magnetic probes of 5.0 and 10mm diameter. Strong retraction forces reaching 6N maximum were obtained by magnetic fluid based on dispersion of SS-µPs. In contrast, the IO-nP-based magnetic liquid generated less attraction force, due to both lower magnetic and solution properties of the IO-nPs. The comparison of the two particles allowed the identification of the rules to engineer the next generation of particles. The results with SS-µPs provide proof on concept that intraluminal injection of magnetic fluid can generate sufficient force for efficient bowel retraction. Thereafter we shall carry out in vivo animal studies for efficacy and safety of both types of ferrofluids.

Assessing the benefits of "gaze-down" display location in complex tasks.

BACKGROUND: Location of the image display is one of several factors that influence perceptual processing and endoscopic manipulation in minimal access surgery. Previous studies have proved the benefits of the gaze-down stance, as compared with the conventional gaze-up stance. This study investigates the effect of the gaze-down stance on the performance of a task with varying manipulative and perceptual demands. METHODS: The participants in this study were 20 medical students. Each student performed endoscopic touching tasks under standard conditions using the Dundee Projection System (DPS) display, positioned to provide gaze-up and gaze-down stances. To increase task complexity, two kinds of manual coordination (unilateral vs bilateral) and three endoscope positions (different positions of misalignment) were used. The outcome measures were task execution time and number of errors. RESULTS: Overall, the gaze-down stance reduced time and errors, as compared with the gaze-up display. However, the benefit obtained from the gaze-down stance was more significant in the more difficult tasks (bilateral task and 90 degrees misalignments). CONCLUSIONS: The gaze-down stance reduces task time and errors, as compared with a gaze-up stance. The reduction in time and errors is more appreciable as task complexity increases.

Characterizing the "gold standard" image for laparoscopic surgery.

BACKGROUND: The term "gold standard" is often used to describe preferred display devices, frequently without substantiating evidence. A meaningful and objective measure of display quality for endoscopic surgery is required. METHODS: Typical colors from five tissue types were arranged in a striped pattern and displayed on four devices: a medical-grade cathode ray tube monitor, a liquid crystal display, a digital light projection display, and an obsolete cathode ray tube (CRT) monitor. The breadth and color contrast of the stripes were adjusted until the patterns became indiscernible to 12 subjects. The data provide a discernibility threshold. RESULTS: The liquid crystal display (LCD) monitor provided the best image. The medical grade and obsolete CRTs were second and third, respectively, and the projection display provided the most inferior image. CONCLUSIONS: A meaningful and relevant measurement of image display quality for laparoscopic surgery based on the discernibility threshold is provided. Of the devices tested, the LCD is the best in terms of image, although the CRT may be preferred at off-axis viewing angles. The projection system, however, offers compensatory ergonomic advantages.

Improving the retention of suturing needles in surgical graspers.

BACKGROUND: Surgical needles are usually held using dedicated grasping instruments. When the tissue to be penetrated is resilient, or the grasping force is low, the needle can swivel, causing it to deviate from the intended path, resulting in suboptimal tissue approximation. Needle swivel is particularly prevalent when needles are not held transversely in the jaws, but it is difficult to maintain a transverse grasp during surgery. An improved swivel-resistant grasper design is proposed. METHODS: Conventional and swivel-resistant graspers were tested to quantify the benefits of the swivel-resistant design. Needles secured in the grasper were repeatedly distracted until swiveling occurred. The torque required to swivel the needles was statistically analyzed. RESULTS: The swivel-resistant grasper offers greatly improved resistance to swivel (p = 0.01) when the needle is not held transversely. CONCLUSIONS: The four-point contact afforded by the modified needle graspers imparts improved needle retention and resistance to swivel.

Optimization of the projection screen in a display system for minimal access surgery.

BACKGROUND: The operative image for minimal access surgery currently is displayed on a monitor located outside the sterile field. It is ergonomically advantageous to locate the image adjacent to the surgeon's hands by projection onto a sterile screen, but there has been no research into the optimal screen material. METHODS: Several screen materials were compared for image resolution, brightness, variation of brightness with viewing angle, and image artifact. RESULTS: Glossy materials perform poorly, whereas finely grained surfaces improve image clarity. Excessive roughness and incomplete opacity limit the image resolution. Conventional screen fabrics are unsuitable in this application. Ambient lighting and projector brightness affect image contrast, but a correct choice of material can address this. Practical issues such as moisture absorbency and ease of sterilization are considered. CONCLUSIONS: Potential screen materials were rejected because of excessive glare, poor resolution, and image artifact. Finely textured surfaces (e.g., polystyrene sheeting) provide an acceptable screen.

Comparison of conventional and gaze-down imaging in laparoscopic task performance.

BACKGROUND: In video-assisted laparoscopy, the image is usually displayed on a monitor placed at approximately eye level. Video projection systems project the image onto a screen placed close to the hands. This is said to be ergonomically superior. To evaluate this approach, a proprietary projection system (PS) was compared to a monitor display (MD). METHOD: The resolution, ghosting, flickering, glare, contrast, color smear, and color matching of the two modalities were compared. A bowel-suturing task was employed to evaluate performance differences. RESULTS: The image displayed by the first-generation PS is inferior to that of the MD in contrast and resolution measures, but it is comparable in the other image qualities. No significant differences in task performance were identified. CONCLUSIONS: The first-generation PS does not confer performance or comfort advantages over an MD. The theoretical advantages of the gaze-down stance are likely to be realized only if a high-quality projector is used.

Depression, visual acuity, comorbidity, and disability associated with age-related macular degeneration.

OBJECTIVE: To examine (1) the prevalence of depressive disorders in community-dwelling adults with advanced age-related macular degeneration (AMD) and (2) the relationship in this population between depression, visual acuity, the number of comorbid medical conditions, disability caused by vision loss as measured by the National Eye Institute-Vision Function Questionnaire (NEI-VFQ) and the vision-specific Sickness Impact Profile (SIPV), and disability caused by overall health status as measured by the Sickness Impact Profile-68 (SIP). DESIGN: Analysis of cross-sectional baseline data from a randomized clinical trial. PARTICIPANTS: Participants were 151 adults aged 60 and older (mean age, 80 years) with advanced macular degeneration whose vision was 20/60 or worse in their better eye. METHODS: Subjects were interviewed using measures of depression, disability, and chronic medical conditions. Visual acuity was obtained. Nonparametric correlation analyses and linear regression analyses were performed. MAIN OUTCOME MEASURES: Structured Clinical Interview for DSM-IV (SCID-IV), Geriatric Depression Scale (GDS), NEI-VFQ, SIPV, and SIP. RESULTS: Of the participants, 32.5% (n = 49) met SCID-IV criteria for depressive disorder, twice the rate observed in previous studies of community-dwelling elderly. Over and above depression (GDS), visual acuity aided in prediction of the level of vision-specific disability (NEI-VFQ and SIPV). CONCLUSIONS: Depressive disorder is a significant problem for the elderly afflicted with advanced macular degeneration. Further research on psychopharmacologic and psychotherapeutic interventions for depressed AMD patients is warranted to improve depression and enhance functioning. Over and above depression, visual acuity aided in predicting vision-specific disability. Treatment strategies that teach patients to cope with vision loss should be developed and evaluated.

A new objective digital computerized vision screening system.

PURPOSE: Fewer than 40% of children in the crucial younger-than-4 age group are evaluated for visual problems by pediatricians. This is due to impracticality from either a clinical or practice efficiency standpoint. Current photoscreening methods require trained readers and suffer from significant subjectivity and interobserver variability. We report a cross-sectional, double-masked study using new digital imaging with objective, automated, computerized image analysis. METHODS: Two-hundred six children aged 9 months to 16 years were prospectively studied in a University-based pediatric ophthalmology practice. Images were taken by volunteers with a modified digital camera which, when downloaded, were analyzed within 35 seconds by new image analysis software. The analysis was compared to a masked review of a complete pediatric ophthalmic exam. RESULTS: Overall agreement between physician and the objective computerized analysis was 86.9%. Positive predictive value was 91%, sensitivity was 89%, and specificity was 83%. CONCLUSIONS: This automated digital imaging screening system eliminates human bias and provides accurate and immediate results. The system requires no special expertise.

Age-related macular degeneration: a randomized clinical trial of a self-management intervention.

The purpose of this study was to conduct a randomized clinical trial to assess whether a self-management group intervention can improve mood, self-efficacy, and activity in people with central vision loss due to age-related macular degeneration (AMD). Ninety-two elderly patients with AMD (average age = 79) from a university ophthalmology clinic were randomly assigned to the self-management intervention (n = 44) or to a wait-list (n = 48). All patients were legally blind in at least one eye. The intervention consisted of 6 weekly 2-hour group sessions providing education about the disease, group discussion, and behavioral and cognitive skills training to address barriers to independence. All participants eventually completed the intervention allowing pre-post comparisons for all patients. The battery of measures included the Profile of Mood States (POMS); Quality of Well-Being Scale; and assessments of self-efficacy, participation in activities, and use of vision aids. Participants' initial psychological distress was high (mean total POMS = 59.72) and similar to distress experienced by other serious chronic illness populations (e.g. cancer, bone marrow transplant). Analysis of covariance testing the primary hypothesis revealed that intervention participants experienced significantly (p = .04) reduced psychological distress (pre mean = 61.45; post mean = 51.14) in comparison with wait-list controls (pre mean = 57.72; post mean = 62.32). Intervention participants also experienced improved (p = .02) self-efficacy (pre mean = 70.16; post mean = 77.27) in comparison with controls (pre mean = 67.71; post mean = 69.07). Further, intervention participants increased their use of vision aids (p < .001; pre mean = 3.37, post mean = 6.69). This study demonstrates that a relatively brief behavioral intervention can substantially reduce psychological distress and increase self-efficacy in elderly adults experiencing vision loss due to macular degeneration. Self-management intervention appears to improve mood, self-efficacy, and use of vision aids, further enhancing the lives of poorly sighted individuals with AMD.

The psychosocial impact of macular degeneration.

BACKGROUND: Age-related macular degeneration (AMD), the leading cause of irreversible blindness and low vision among the elderly, has not been well studied with regard to its impact on daily life. This study was designed to demonstrate the impact of AMD on quality of life, emotional distress, and functional level. PARTICIPANTS: The study sample consisted of 86 elderly adults (average age, 79 years) with AMD who were legally blind in at least 1 eye. Participants completed a battery of measures that included the Quality of Well-being Scale, the Instrumental Activities of Daily Living index, self-rated general health status, and the Profile of Mood States. RESULTS: Persons with AMD experienced significant reductions in key aspects of daily life. Their ratings for quality of life (average Quality of Well-being Scale score=0.581) and emotional distress (average Profile of Mood States total score=65.36) were significantly worse than those for similarly aged community adults and were comparable with those reported by people with chronic illnesses (eg, arthritis, chronic obstructive pulmonary disease, acquired immunodeficiency syndrome, and bone marrow transplants). Patients with AMD were also more likely than a national sample of elderly individuals to need help with daily activities. Visual acuity was related to ability to carry out daily activities (Instrumental Activities of Daily Living, r=0.28, P=.008). Quality of life ratings were significantly related to the ability to carry out daily activities (r=-0.38, P=.001), self-rated general health status (r=-0.21, P=.05), and emotional distress (Profile of Mood States total score, r=-0.25, P=.02). Individuals with a shorter period of perceived vision loss were more likely to report high levels of emotional distress (r=-0.24, P=.03) than those with a longer period of perceived vision loss. Further, those who were blind in 1 eye were even more significantly distressed than those who were blind in both eyes. CONCLUSIONS: Elderly persons with AMD causing legal blindness in 1 or both eyes have significant emotional distress and profoundly reduced quality of life and need help with key daily activities.

The use of capsaicin in herpes zoster ophthalmicus neuralgia.

The treatment of neuralgia which occurs during and following herpes zoster ophthalmicus is often unsatisfactory. Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide) is a drug which depletes substance P and may be effective in inhibiting pain. We utilized topical capsaicin to the affected dermatome five times daily for 4 weeks in 6 patients with acute and post herpetic neuralgia. In four cases pain was markedly relieved and narcotic medications were either discontinued or significantly reduced. In two cases, pain was not reduced. Four patients had side effects including burning sensation at the site of the drug administration (4 cases), dermatitis as a result of overuse of the drug (2 cases) and hyperesthesia (1 case). Our results suggest that capsaicin may be a useful therapy for the alleviation of pain in some individuals with herpes zoster ophthalmicus. However, controlled studies are needed to establish these results.

Transplantation of congenitally opaque corneas.

AIMS: To assess retrospectively the prognosis and complications of corneal grafting for congenital opacities. METHODS: Fifty eight eyes of infants and young children with congenital corneal opacities were studied retrospectively. Preoperative diagnoses included sclerocornea (27 eyes), Peters' anomaly (17 eyes), partial sclerocornea (12 eyes), and congenital glaucoma (two eyes). Penetrating keratoplasty was performed between 5 days and 65 months of age with a mean follow up of 40 (SD 29) months. RESULTS: The overall success (including regrafts) was 70% in eyes with sclerocornea, 83% for partial sclerocornea, and 100% for Peters' anomaly. However, 23 eyes had to be regrafted between 2 weeks and 110 months postoperatively. The probability of maintaining a clear graft, calculated by survival analysis, was 75% (SE 6%) at 1 year and 58% (7%) at 2 years for the entire group. Complications included cataract development (12 eyes), secondary glaucoma (14 eyes), epithelial defects (six eyes), band keratopathy (five eyes), retinal detachment (three eyes), wound leakage (two eyes), retrocorneal membrane (one eye), and microbial keratitis (two eyes). CONCLUSIONS: It is concluded that corneal grafting for congenital opacities in infants has an excellent potential for long term survival and should be performed as early as possible for unilateral as well as bilateral involvement. The postoperative course is complex and often requires regrafting.

11-0 mersilene as running suture for penetrating keratoplasty.

We evaluated astigmatic results and complications of the combined suturing technique in penetrating keratoplasty by using 11-0 Mersilene as a running suture. Twenty-seven grafts were studied for a follow-up that ranged between ten and 46 months (mean, 27.2 months). During the study, complications included three graft failures, one instance of inadvertent breakage of the running suture, one instance of one suture bite cutting through the recipient cornea, and suture microabscesses in two eyes. Keratometric astigmatism was 2.5 +/- 2.1 diopters at six months, was 2.4 +/- 2.3 diopters at 12 months, and was 2.5 +/- 2.0 diopters at 24 months. Our data indicate that 11-0 Mersilene is suitable for the running suture in corneal transplants in the combined technique. Spontaneous suture dissolution did not occur throughout the follow-up period. The use of a less biodegradable suture enables the maintenance of low levels of astigmatism for longer periods when compared with a previous study that used 11-0 nylon suture.