Dietary Environment Assessed Using Visual Measurements of Different Seated Wheelchair Postures

Sunday, 27 July 2014

Yoko Tsuji, ME, RN
Kanagawa University of Human Services, Yokosuka, Kanagawa, Japan
Etsuko Yokoyama, MSN, RN
National Defense Medical College, Tokorozawa, Saitama, Japan


Elderly individuals experience lower back muscle weakness that limits the upper limb range of motion while seated in a wheelchair and interferes with their activities of daily living. Furthermore, those who cannot self-adjust their seated posture are unable to freely move their trunk and head; thus, reducing their field of vision and further restricting the activities that they can perform. When adjusting one’s lifestyle to accommodate age-related changes, meals play a crucial role not only in sustaining life, but in providing taste and happiness.

Important points in nursing intervention for the provision of delicious meals involves choosing cutlery suited to physical function, providing tableware that allows meals to be easily consumed and dietary contents to be easily ascertained, arranging seating that allows individuals to concentrate on meal consumption, and preparing dietary environments in which individuals can interact with others. Meals for elderly individuals who live in facilities are not provided in their private rooms, but rather in dining rooms at large tables surrounded by chairs, although majority of the individuals consume their meals while remaining seated in wheelchairs. The height at which the meal is consumed is identical for everyone because the meals are served at the same table. However, individuals sit in wheelchairs that are suitable to their physiques, and differences in the perceptions of meals can also be expected according to the state of each individual’s visual function. Therefore, it appears important to analyze visual information to assess the dietary content and gain an understanding of how individuals perceive meals.

To date, previous studies have examined the effects of visual information changes on posture, and according to measurements collected for subjects who walk, the effect on posture has been reported as greater in elderly individuals than in young individuals. Further, studies of wheelchairs have analyzed the wheelchairs while in motion but few studies have focused on “seated wheelchair postures” and the “line-of-sight.” Therefore, the present study aimed to examine the visual information obtained from different postural angles to elucidate the amount of information obtained through the line-of-sight from a wheelchair in a dietary environment.


 The line-of-sight was measured using the Eye Tracking System EMR-8B (NAC Image Technology, Tokyo, Japan; hereinafter, EMR). This device uses detectors that are attached to a baseball cap, and thus can visualize the line-of-sight positions of images in the user’s visual field from a relative distance between the position of near-infrared illumination corneal reflection and the central pupil position. The EMR is a non-invasive device weighing 250 g. In the present study, we used a visual field camera at a horizontal angle of 92°, with a data sampling rate of 29.96 Hz and data resolution at a viewing angle of 0.1°. The temperature, humidity, and illumination in the test room were adjusted to be constant.

The test, which was conducted in a private room, aimed to represent an environment in which meals are consumed while being seated in a wheelchair. Rice, miso soup, egg, and stir-fried vegetables were placed on a table as dietary models, and 7 pelvic inclination angle patterns (0°, 5°, 10°, 15°, 20°, 25°, and 30°) were examined while subjects were seated in a wheelchair. The line-of-sight and postural angles were each measured for 3 min. Subjects were instructed to “look at the meals for 3 min” while seated in a wheelchair, at which time the measurements were initiated. After adjusting the seated posture, recordings of the posture were made from the right side.

For the analysis, visual information from 1 min in the middle of the 3-min measurement period was used to analyze the line-of-sight. Time spent gazing at something other than the meal and time spent gazing at the meal were compared. The height of line-of-sight was examined from the following 2 points taken from the recorded images: the distance from the corner of the eye to the meal and the vertical height of the table. Using an angle of 0° as a basic value, we used the Friedman test and Wilcoxon signed-rank test to examine the values between each postural angle. The SPSS 18.0 statistical software package (SSPS, Inc., Chicago, IL, USA) was used, and the level of significance was set at 5%.

This study was approved by the ethics committee of the Japanese Red Cross College of Nursing. On the test day, the subjects were provided with written and verbal explanations that it was their right to choose to collaborate in this study, they were free to refuse to participate, and their privacy would be protected. After they provided their consent, the test was initiated.


Subjects comprised 13 healthy adult women with no lower back pain and no visual function abnormalities. The mean age was 23 ± 6 years, the mean height was 159.8 ± 4.8 cm, and the mean weight was 51.05 ± 7.27 kg. During the test, almost no head movement or lowering of the jaw position was observed. During the line-of-sight measurements, no significant differences between the postural angles were observed with regard to the time spent gazing at things other than the meal. Analysis of the images revealed significant differences between the angles with respect to the height of the line-of-sight (p<0.000). When a pelvic inclination angle of 0° was compared with the other angles, significant differences were seen at angles of 10°, 20°, 25°, and 30°, and the line-of-sight increased with each increase in angle (p<0.05). Significant differences were also noted between each postural angle with respect to the distance from the corner of the eye to the meal (front of the tray; p<0.000). Furthermore, significant differences were observed at angles of 20°, 25°, and 30°, compared with the inclination angle of 0° (p<0.05). A comparison of the height from the posture and corner of the eye to the table also revealed significant differences (p<0.001), with differences noted at inclination angles of 10–30° when compared with an inclination angle of 0° (p<0.05).


No significant differences in the quantity of eye gaze were noted with respect to changes in posture. However, compared with an angle of 0°, changes in the pelvic inclination angle resulted in an increase in the height of the line-of-sight, with a shorter distance to the meal, and a shorter distance from the corner of the eye to the table. This shows that while changes in posture did not result in statistically significant differences in the meal-related information obtained, there were changes in the information obtained regarding the meal contents. The visual field images obtained from the EMR showed that the distances from which the side dishes (egg, stir-fried vegetables) on the far side of the meal tray were perceived lengthened with the increased pelvic backward inclination angle, suggesting that meal contents that are placed at a greater distance are not perceived 3-dimensionally, but as a planar image.

Dietary intake is a basic criterion for maintaining quality of life. Therefore, the dietary environment should be examined in terms of the table height and the meal placement at which the colors and shapes of foods can be visually perceived to enhance appetite while considering an individuals’ posture. The subjects in the present study were young, and therefore no significant head movement was noted during the short measurement time. In the case of elderly individuals without the provision of a dietary environment, the range of motion will be restricted, starting with the neck; this will result in an increased amount of time required to consume the meal, thereby making meal consumption a distressful rather than an enjoyable experience.

An ideal dietary environment for wheelchair-bound individuals would involve the arrangement of a seated wheelchair posture suited to the individuals’ physical condition, thereby increasing their appetite. To achieve this, we must consider nursing dietary environment interventions such as adjustments to table heights and meal placements to accommodate seated wheelchair postures based on the physical status obtained during the daily health assessments conducted by nurses.