[The basics for establishing a needlestick injury prevention program in hospitals].

Although the risk of occupationally acquired infection is a matter of considerable concern for health care workers, the problem of needlestick injuries has yet to be fully understood in Japan. We investigated 257 cases of needlestick injuries in five Nagoya Municipal Hospitals from 1989 to 1994 using the Japan EPInet. The number of needlestick injuries increased each year of the study. In one of these hospitals, the Higashi Municipal Hospital, a specialist committee began activities in April, 1993, and protective equipment and devices were also introduced during 1994. HCV contamination injuries accounted for 70%-80% of the total number of injuries reported during the 1991-1994 period at the four hospitals and during 1991-1992 period at the Higashi Municipal Hospital. At the Higashi Municipal Hospital, HCV contamination injuries decreased from 22 cases (48%) in 1993, to 15 cases (25%) in 1994. The use of the Japanese EPINet for analytical purposes enabled us to clearly identify the causes and status of needlestick injuries, resulting in the establishment of an effective prevention program.

Comparison of readability between liquid crystal displays and cathode-ray tubes.

Flat-panel displays, especially liquid crystal displays (LCDs), are almost universally used today. Do LCDs assure better readability than cathode-ray tubes (CRTs)? Two experiments were carried out to determine which type of display is better using a newly developed device. Four types of displays were tested; negative and positive CRTs, and LCDs with and without backlighting. Variables were the type of display, age, and gender. At first, analyses of readability using eye movements were conducted. Middle-aged subjects showed slower reading speed than young subjects. Then, experiments of pupillo-accommodative functions were carried out. Non-backlit LCDs reduced focusing speed among young subjects and reading performance in middle-aged subjects. Since middle-aged workers have more difficulties than young workers, they should have their vision properly corrected for VDT viewing, more appropriate displays and a more comfortable illuminance environment than young workers.

Do liquid crystal displays assure better readability than cathode-ray tubes?

Flat-panel displays, especially liquid crystal displays (LCDs), are now firmly established as important devices for information displays. But do LCDs assure better readability than cathode-ray tubes (CRTs)? We carried out an experiment using four types of displays: negative and positive CRTs, and LCDs with and without backlighting. A syllable-checking task using the Japanese katakana alphabet was conducted among fifteen healthy workers. They were divided into three groups; Group 1 had five young males aged 25 to 29, Group 2 was made up of five young females aged 18 to 24, and Group 3 consisted of five middle-aged workers who were 40 to 50 years old. We used four ambient light levels: 200 lx, 500 lx, 1250 lx without reflected glare, and 500 lx with reflected glare, on the display screens from behind. The illuminance of the glare was approximately 200 cd/m2. Multiple regression analysis showed that non-backlit LCDs reduced reading performance in middle-aged subjects significantly. Since middle-aged workers have more difficulties than young workers, they need more appropriate displays and a more comfortable illuminance environment than younger workers.

An experimental study on the objective measurement of accommodative amplitude under binocular and natural viewing conditions.

A high resolution optometer makes it possible to measure changes in refractive power objectively using reflected light from the fundus of the eye. There are limitations in that the subject has to see the target monocularly through a hole in the instrument. In the present study, we attempted to measure the accommodation and pupillary response with a newly developed device as a means to measure these factors in both binocular and natural viewing conditions. We compared the subjective accommodative amplitude levels obtained from the near-point distance with those of objective accommodative amplitude obtained in earlier studies using a monocular internal target. The amplitude of accommodation of the cases with binocular, natural viewing conditions was approximately 0.7 D larger than with monocular, internal target gazing. In previous studies, the difference between the subjective amplitude of accommodation and the results of the objective measurements, had been reported to be approximately 2 D, and was explained by the depth of focus. However, the difference between the subjective and objective amplitude of accommodation under binocular, natural viewing was smaller than that between the subjective and objective measurements (under monocular internal target gazing) from previous studies. This leads us to believe that besides the depth of the focus, we should consider the fact that the advantageous conditions inherent in binocular, natural viewing may increase the amplitude of accommodation. In the measurement of accommodative amplitude, the use of objective measuring methods are not affected by the subjects' subjective judgement.