Biomedical subjects

S Taptagaporn

Publications and source records attributed to S Taptagaporn.

4 recordsLinked to original sources

PubMed1995

Visual comfort in VDT workstation design.

This study aims to give recommendations for a comfortable visual display terminal (VDT) workstation design by investigating physiological resting states of the eye in 3 experiments. Dark vergence, in experiment 1, was evaluated to be at a distance of about 50 cm from the eye as an average of 14 subjects. Dark vergence was found to shift farther with an upward gaze while a nearer shift occurred with a downward gaze. In experiment 2, the average dark focus for 11 subjects was found to be 1.4 diopters (D) or a distance of about 74 cm from the eye. Experiment 3 ascertained the superiority of a positive display polarity (dark characters on a bright background) under 500 1x illuminated level, by using pupil size analysis in 10 subjects. The ergonomic recommendations for a VDT workstation obtained in this study are a positive display polarity under regular lighting condition, a downward gaze, and a viewing distance between 50 and 70 cm.

Adult↗

PubMed1994

Physiological indices of visual fatigue due to VDT operation: pupillary reflexes and accommodative responses.

In spite of the clarification of some significant physiological factors of visual fatigue caused by VDT work, pupillary reflexes have not been studied as to how they are affected after prolonged visual work. This study examined visual function changes objectively in terms of pupillary reflexes and lens accommodative responses after a 4-hr VDT operation task. The relationship between the two functions was also examined. Two measurements in this paper revealed the physiological function changes due to VDT operation. The subjects involved were five students with an average age of 22.6 years. First, near-reflex measurement ascertained decreases in amplitude and the velocity of accommodation function after the visual task. Second, light-reflex measurement revealed a delay of the reflex, an increase in the amplitude of the reflex, and a decrease in pupil size after the visual task. A weak correlation between the decrease in pupil size and accommodation function was found. The occurrence of visual fatigue due to 4-hr VDT operation was also confirmed by CFF measurements and reported subjective visual symptoms in this experiment.

Accommodation, Ocular↗

PubMed1993

Visual comfort in VDT operation: physiological resting states of the eye.

To recommend a comfortable visual display terminal (VDT) workstation design in an aspect of visual ergonomics, physiological resting states of the eye in 3 visual systems, pupil, vergence, and accommodation, were objectively investigated in 3 experiments. Experiment 1 ascertained a positive display polarity (dark characters on a bright background) and an illumination level of 500 lx to be the most appropriate working conditions, by using pupil analysis and subjective visual comfort in 10 subjects. Dark vergence, in experiment 2, was evaluated to be at a distance of about 50 cm from the eye, as an average in 14 subjects. Dark vergence was found to shift farther with an upward gaze while a nearer shift occurred with a downward gaze. In experiment 3, the average dark focus for 11 subjects was found to be 1.4 diopters (D) or a distance of about 74 cm from the eye. The positive correlation between refractive status of the eye and dark focus was statistically significant (r = 0.602). The ergonomic recommendations for a VDT workstation obtained in this study are a positive display polarity with an appropriate lighting condition, a downward gaze, and a viewing distance between 50 and 70 cm. These recommendations are considered to reduce visual fatigue due to prolonged VDT work and to facilitate visual comfort at work.

Accommodation, Ocular↗

PubMed1990

How display polarity and lighting conditions affect the pupil size of VDT operators.

This study ascertained that CRTs using a positive display polarity (dark characters on bright background) are ergonomically more appropriate for VDT operators than ones using a negative display polarity (bright characters on dark background), using both physiological and psychological indices. Differences of pupil size and subjective evaluation of visual comfort while undertaking visual tasks were examined for six experimental conditions (two CRT display types in three different illuminated levels). Pupil diameter was not affected greatly when working with the positive display for different illumination levels. The positive display also caused smaller differences in pupil diameter when viewing visual targets, namely CRT display, script, and keyboard, for all lighting conditions. The majority of the subjects also appreciated working with the positive CRT display at a regular office illumination level.

Adult↗