Effects of a chair for ophthalmic microsurgery on pressure distribution and pelvic tilt in surgeons.

BACKGROUND: Ophthalmic surgeons experience high levels of physical strain in the neck, lower back, and buttocks. While ergonomic interventions may help to solve these problems, only a few studies have reported chair designs for ophthalmic microsurgery. OBJECTIVE: To design a chair that reduces the physical strain on surgeons and examine its effectiveness in improving posture and reducing seat pressure. METHODS: A prototype chair with a three-dimensional seat surface and a sliding adjustment mechanism for the backrest was designed to fit the surgeon's body. A conventional chair (A) and the prototype chair (B) were compared during microsurgeries performed by five surgeons. Seat pressure was measured using a pressure-sensing device, and the pelvic tilt angle was measured using a gyroscope sensor. RESULTS: A paired t-test indicated significant differences between the chairs: average seat pressure was 70.4±12.7 mmHg for A and 40.5±3.8 mmHg for B (p = 0.008); the maximum seat pressure was 242.2±19.7 mmHg for A and 170.5±38.5 mmHg for B (p = 0.024); contact area was 906.1±114.5 cm2 for A and 1,255.9±60.1 cm2 for B (p < 0.001); and relative value of the pelvic tilt angle was -13.7°±3.7° for A and -7.1°±4.9° for B (p = 0.032). CONCLUSIONS: The prototype chair was associated with lower seat pressure and maintenance of a more neutral posture than the conventional chair, indicating that it may help to reduce physical strain in ophthalmic surgeons.

Application of Zen sitting principles to microscopic surgery seating.

This paper describes the application of an alternative seating concept for surgeons that reflects the research of Zen sitting postures, which require Zazen meditators to maintain fixed postures for long durations. The aim of this alternative approach is to provide sitters with a seat pan with sacral support(1) that provides a more even distribution of seat pressures, induces forward pelvic rotation and improves lumbar, buttock and thigh support. This approach was applied to the development of a chair for microscopic surgery. The experimental chair is a seat pan that closely matches the three-dimensional contours of the user's buttocks. Seat comfort was evaluated by comparing both changes in pelvic tilt and seat pressure distributions using Regionally-Differentiated Pressure Maps (RDPM) with subjective ratings of surgeons while operating in prototype and conventional chairs. Findings include that the sacral support of the prototype chair prevents backward pelvic rotation, as seen in zazen (Zen sitting postures). Preliminary data suggests that the prototype provided greater sitting comfort and support for constrained operating postures than did the conventional chair. These findings support the selective application of concave-shaped seat pans that conform to users' buttocks and reflect Zen sitting principles.

Prevention of deep vein thrombosis in VDU work.

This paper introduces preventive measures against Deep Vein Thrombosis (DVT) during Visual Display Units (VDU) work. Four experiments were conducted in order to address this issue. The effectiveness of the preventative measures was evaluated by measuring foot swelling. The results indicated that the following 3 methods would be particularly effective: (a) occasionally adopting a reclining posture with a footrest, (b) 10-min walking every 50-60 min of VDU work, and (3) stretching. In addition we predicted that taking a deep breath could sometimes be effective. DVT is likely to occur in daily life and its incidence can be related to the long-term postures associated with VDU work. This paper suggests that VDU workers should be aware of the risk of DVT and take preventative measures.

Evidence-based ergonomics. A comparison of Japanese and American office layouts.

There is a variety of alternatives in office layouts. Yet the theoretical basis and criteria for predicting how well these layouts accommodate employees are poorly understood. The objective of this study was to evaluate criteria for selecting office layouts. Intensive computer workers worked in simulated office layouts in a controlled experimental laboratory. Eye movement measures indicate that knowledge work requires both concentration and interaction. Findings pointed to one layout as providing optimum balance between these 2 requirements. Recommendations for establishing a theoretical basis and design criteria for selecting office layouts based on work style are suggested.