PURPOSE: To investigate ocular fatigue after the use of a head-mounted display (HMD)-type virtual reality device.METHODS: Healthy adult volunteers were examined for ocular fatigue before and after watching videos for 10 min with an HMD-type virtual reality device. Subjective ocular fatigue was measured using a questionnaire. Objective fatigue was measured using the critical flicker fusion frequency (CFF), high frequency component of accommodative microfluctuation, and accommodation amplitude. The accommodation amplitude was measured using the push-up method and the dynamic measurement mode of the autorefractometer. Changes in the spherical equivalent were also measured.RESULTS: The questionnaire-based subjective ocular fatigue increased (p = 0.020) after use of the HMD device. In the dominant eye, the high frequency component of accommodative microfluctuation increased (p < 0.05). The accommodation amplitude using the push-up method was decreased in the nondominant eye (p = 0.007), and temporary myopia was observed (p < 0.05). However, there was no increase in ocular fatigue in the CFF or the accommodation amplitude using the dynamic measurement mode, which showed no significant difference before and after using the HMD device (p > 0.05).CONCLUSIONS: A subjective test and some objective tests suggested that use of the HMD-type virtual reality display increased ocular fatigue. However, no increase in ocular fatigue was measured using CFF nor in the accommodation amplitude using the dynamic measurement mode which was a limitation of the study. More studies with the aim to alleviate ocular fatigue after using HMD-type virtual reality devices are therefore needed.
Adult ; Asthenopia ; Fatigue ; Flicker Fusion ; Humans ; Methods ; Myopia ; Volunteers

BACKGROUND: Fatigue and sleepiness are inter-related and common among road transport drivers. In this study, sleep deprivation and fatigue among chemical transportation drivers were examined. METHODS: A cross-sectional study surveying 107 drivers from three hazardous types of chemical production and transportation industries (nonflammable gases, flammable gases, and flammable liquids) was conducted. Data on sleep deprivation were collected using questionnaires of the Stanford Sleeping Scale and the Groningen Sleep Quality Scale. Fatigue was assessed using an interview questionnaire and a flicker fusion instrument. RESULTS: Chemical drivers had a mean sleeping scale (Stanford Sleeping Scale) of 1.98 (standard deviation 1.00) and had a mean score of 1.89 (standard deviation 2.06) on the Groningen Sleep Quality Scale. High-risk drivers had higher scores in both the Stanford Sleeping Scale and the Groningen Sleep Quality Scale with a mean score of 2.59 and 4.62, respectively, and those differences reached statistical significance (p < 0.05). The prevalence of fatigue, as assessed through a critical flicker fusion analyzer, subjective fatigue question, and either of the instruments, was 32.32%, 16.16%, and 43.43%, respectively. Drivers who slept <7 hours and had poor sleep quality were found to have more fatigue than those who slept enough and well. Drivers who had a more sleepiness score resulted in significantly more objective fatigue than those who had a less sleepiness score. CONCLUSION: Sleep quality and sleeping hour can affect a driver's fatigue. Optimization of work–rest model should be considered to improve productivity, driver retention, and road safety.
Cross-Sectional Studies ; Efficiency ; Fatigue* ; Flicker Fusion ; Gases ; Prevalence ; Sleep Deprivation* ; Thailand* ; Transportation*

OBJECTIVE: This study aimed to investigate the effects of alcohol on daytime sleepiness, psychomotor performance, and subjective response in healthy young men with different ALDH2 genotypes. METHODS: A total of 24 males, half with the active ALDH2*1/*1 and the rest with inactive the ALDH2*1/*2, were selected through genotyping. In a double-blind, placebo-controlled crossover design, each subject consumed either a 0.5 g/kg dose of alcohol or placebo in the morning on two separate occasions, a week apart. Multiple Sleep Latency Test, a battery of psychomotor tests (Critical Flicker Fusion Threshold, Choice Reaction Time, Compensatory Tracking Task, Digit Symbol Substitution), questionnaire for subjective response and modified Epworth Sleepiness Scale were administered. RESULTS: Daytime sleep latency was significantly decreased after alcohol intake in the morning compared to placebo, and the decrease was much greater in subjects with ALDH2*1/*2 than in subjects with ALDH2*1/*1. Psychomotor function was significantly impaired after alcohol intake in the morning compared to placebo, in subjects with ALDH2*1/*2. Subjective response was significantly negative or intense after alcohol intake in the morning, compared to placebo, in subjects with ALDH2*1/*2. Subjective daytime sleepiness was significantly increased after alcohol intake compared to placebo, in subjects with ALDH2*1/*2. CONCLUSION: These results supported that ALDH2 polymorphism might be one of important factors in determining the effects of alcohol on the various psychobehavioural functions as well as on patterns of alcohol use.
Cross-Over Studies* ; Flicker Fusion ; Genotype* ; Humans ; Male ; Psychomotor Performance* ; Surveys and Questionnaires ; Reaction Time

OBJECTIVE: New antidepressant, nefazodone is classified as a serotonin -2 antagonist/reuptake inhibitor like old antidepressant, trazodone. Nefazodone, however, differs from trazodone in that it lacks anti-histaminergic properties and in that it has some norepinephrine reuptake inhibitory properties. These differences may account for the differences between the two drugs in the side effect profiles. This study was conducted to compare the acute effects of nefazodone on the psychomotor performance with those of trazodone. METHODS: The subjects were 12 healthy male volunteers aged between 20-40 years. A single, oral starting dose of nefazodone or trazodone was administered in a double-blind, randomized latin-square design with a 1-week interval between each drug switch. Psychomotor performances were assessed at 1 hour before and at 2 hours after administration of nefazodone 50 mg, nefazodone 100 mg or trazodone 50 mg. The measures of psychomotor performance included Vienna Determination Unit for complex choice reaction time, Critical Flicker Fusion Test, and Grooved Pegboard Test. RESULTS: In the Vienna Determination Unit, when 'within drug effect' (pre- vs. post-medication) was analyzed, nefazodone 100 mg decreased complex choice reaction time in both subtest 2 and subtest 3. Nefazodone 50 mg also decreased the reaction time in subtest 3 but not in subtest 2 which was more difficult and demanding task than subtest 3. On the other hand, no significant changes in the reaction time were observed with trazodone 50 mg in either subtest 2 or subtest 3. When 'between drug effect' was analyzed, however, the differences between drugs were not found to reach statistically significant level. No significant 'between drug effect' or 'within drug effect' was observed in Critical Flicker Fusion Test and Grooved Pegboard Test. CONCLUSION: Although the differences between nefazodone and trazodone did not reach statistically significant level, the results on the complex choice reaction time suggest that al least a single starting dose of nefazodone up to 100 mg does not impair psychomotor performances and it might have a less detrimental effect than trazodone on the psychomotor performance.
Administration, Oral* ; Flicker Fusion ; Hand ; Healthy Volunteers* ; Humans ; Male ; Norepinephrine ; Psychomotor Performance* ; Reaction Time ; Serotonin ; Trazodone* ; Volunteers

OBJECTIVE: For the optimal use of antidepressants, it is important to consider the behavioral effects of drugs affecting the real lives of depressed patients, as there is little difference in therapeutic effects between drugs. The aim of this study was to determine the acute pharmacodynamic effects of two recently introduced antidepressants, venlafaxine and mirtazapine, on psychomotor performance, motor activity and daytime sleepiness. METHODS: Twelve healthy male volunteers received a single dose of venlafaxine 37.5 mg, mirtazapine 15 mg or amitriptyline 25 mg (positive control) at one-week intervals in a double-blind, placebo-controlled, crossover design. Volunteers wore an actigraph on their non-dominant wrist for the duration of each test day. A battery of psychomotor tests was performed prior to dosing and at 2 and 6 h post-dose. Subjective daytime sleepiness was also assessed at the end of each test day. RESULTS: Venlafaxine did not affect psychomotor performance, motor activity and daytime sleepiness. Mirtazapine decreased thresholds in critical flicker fusion frequency, increased reaction times in choice reaction tests, and increased peripheral reaction times in compensatory tracking tests. It also caused significant daytime sleepiness and decreased motor activity. CONCLUSION: The differences in the behavioral effect profiles presented in this study should assist in the selection or scheduling of antidepressants.
Amitriptyline ; Antidepressive Agents ; Cross-Over Studies ; Flicker Fusion ; Humans ; Male ; Motor Activity* ; Psychomotor Performance* ; Reaction Time ; Volunteers ; Wrist ; Venlafaxine Hydrochloride

To clarify that the psychosocial factors affect the eye strain of the VDT workers, self-reporting questionnaire about eye strain, critical flicker fusion(CFF), and 12-item version of General Health Questionnaire(GHQ) were carried out to 13 female VDT workers who have done the electronic editing and 10 female controls who were nurses in one hospital. The sum of eye symptoms of VDT workers were significantly higher than controls, but CFF of both groups were not different. And the sum of eye symptoms and CFF were not correlated. High stress group(sum of GHQ > 3) shows significantly more eye symptoms than low stress group. This result suggest that the psychosocial factors could affect the eye strain of VDT workers.
Asthenopia ; Female ; Flicker Fusion* ; Humans ; Psychology ; Word Processing ; Surveys and Questionnaires

OBJECTIVES: The aim of this study was to evaluate the psychiatric function and quality of life of the chemical workers who had been exposed to long-term, low-level organic solvents in the Y industrial complex. METHODS: A total of 144 male workers, of whom 82 were in the exposed group and 60 in the unexposed-control group, were evaluated by using Symptom Checklist-90-R(SCL-90-R), series of neuropsychological tests(critical flicker fusion threshold, CFFT); choice reaction time, CRT; compensatory tracking task, CTT); digit symbol substitution test, DSS), and the Korean version of the SmithKline Beecham Quality Of Life scale(KvSBQOL). For the statistical analyses, comparisons of the means of the two groups were performed for each variable with two-tailed t-test as well as ANCOVA including age and education as covariates. RESULTS: For the SCL-90-R, the nine symptom scales and the three global indices were clinically within normal range in both groups. However, the scores on the symptom scales of 'somatization', 'depression', 'hostility' and 'phobic anxiety', and those on the global indices of 'global severity index' and 'positive symptom total', were significantly higher in the exposed group than in the unexposed group. In terms of the neuropsychological function and the quality of life, there wes no significant difference between the two groups. CONCLUSIONS: These findings suggested that the long-term exposure to mixed organic solvents, even at the low level below the permissible exposure limit, might induce some psychiatric problems.
Education ; Flicker Fusion ; Humans ; Male ; Mental Health ; Quality of Life* ; Reaction Time ; Reference Values ; Solvents* ; Weights and Measures

OBJECTIVE: The purpose of this study was to evaluated the effects of alcohol on neurocognitive function, psychomotor performance and subjective response in healthy Korean adults with different ALDH2 genotypes. METHOD: A total of 24 males, half with active ALDH2*1/2*1 and the other with inactive ALDH2*1/2*1, was selected through genotyping using restriction fragment length polymorphism. In a double-blind, placebo-controlled cross-over design, each subject consumed 0.5g/kg dose of alcohol, given as a mixture of 40% vodka and orange juice, and placebo(orange juice) on two separate occasions on an average of weekly intervals. The blood alcohol concentrations(BACs) were measured using a breath analyzer at baseline and at 30, 60 minutes after drinking. P300s were measured at baseline and at 30 minutes after alcohol and placebo intake. Vital signs and psychomotor performance[Critical Flicker Fusion Threshold(CFFT), Choice Reaction Time(CRT), Digit Symbol Substitution(DSS)] were measured at baseline and at 60 minutes after alcohol and placebo intake. Subjective responses were measured at the end of the study. The statistical analysis focused on whether there were any differences between groups with different ALDH2 genotypes. RESULTS: The major results are as follows. 1) BACs in inactive group were overall equivalent to those in the active group. Only in terms of time, BACs were significantly higher overall at 30 minutes than at 60 minutes after alcohol intake. 2) Pulse rates were significantly increased after alcohol intake compared with placebo, and the increase was greater in the inactive than in the active group. 3) P300 latencies in leads Fz(frontal), Cz(cental) and Pz(parietal) were significantly increased after alcohol intake compared to placebo, and the increase was greater in the inactive than in the active group. P300 amplitudes in leads Cz and Pz were significantly decreased overall after alcohol intake compared to placebo. 4) Compared with placebo, alcohol produced significant effect on the psychomotor performance : impairment in the inactive group, improvement in the active group. 5) Compared with placebo, alcohol significantly induced a negative or an intense effect on the subjective responses in the inactive group, but little negative and even a somewhat positive effect in the active group. CONCLUSIONS: These results suggest that ALDH isozyme variance might be an important factor to determine the effects of acute dose of alcohol on the various psychobehavioural functions and also to determine the alcohol use pattern and to predict the future development of alcohol overuse and/or abuse.
Adult ; Citrus sinensis ; Cross-Over Studies ; Drinking ; Flicker Fusion ; Genotype* ; Heart Rate ; Humans ; Male ; Polymorphism, Restriction Fragment Length ; Psychomotor Performance* ; Vital Signs

This study was done to compare the effects of nemonapride on cognitive and psychomotor performance and sedation with those of classical antipsychotics in normal adults. Single doses of three antipsychotics (chlorpromazine 50mg, haloperidol 2mg and nemonapride 3mg) and placebo were given to 8 healthy male volunteers at weekly intervals, in a double-blind Latin square design. All subjects completed a battery of cognitive and psychomotor pelformance tests (Critical Flicker Fusion Threshold : CFFT, Choice Reaction Time : CRT, Compensatory Tracking Test : CTT, Digit-Symbol Substitution Test DSST) and self-estimate for sedation using visual analog rating scales at pre-dose and 2, 4, 6, 8hr post-dose. The results were as follows : 1) Chlorpromazine 50mg significantly impaired CFFT, CRT, CTT and DSST compared to placebo and showed the most potent sedative effect among the test drugs. These effects occurred in almost all ranges of time points with peak effEct at 4hr post-dose. 2) Haloperidol 2 mg did not impair any cognitive or psychomotor performances. There was no sedative effect as well. 3) Nemo-napride 3 mg selectively impaired CFFT (at 2 and 6hr post-dose), total reaction time (at 4hr post-dose) of CRT and DSST (at 4 and 6hr post-dose). Sedative effect occurred more significantly than placebo at 4 and 6 hr post-dose. These results indicate that nemonapride 3mg seems to have the intermediate profiles between chlorpromazine 50mg and haloperidol 2mg in terms of cognitive and psychomotor effects as well as sedative effect. In addition, inspection of the results suggest that the cognitive and psychomotor effects could be secondary to sedative effect.
Adult* ; Antipsychotic Agents ; Chlorpromazine* ; Flicker Fusion ; Haloperidol* ; Humans ; Hypnotics and Sedatives ; Male ; Psychomotor Performance* ; Reaction Time ; Volunteers ; Weights and Measures

OBJECTIVES: The purpose of this study was to examine the differences of past histories, current symptoms, treatment responses and cognitive functions between smoking and nonsmoking schizophrenic patients. METHODS: The subjects were composed of 67 schizophrenic patients including 36 smokers and 31 non-smokers. They were examined by psychiatric history checklist, Simpson and Angus's rating scale for extrapyramidal side effects, positive and negative syndromes scale(PANSS), global assessment scale(GAS), and Vienna test including Standard Progressive Matrices(SFM), Cognitron, and Flicker Fusion Analyzer(FFA). RESULTS: The results were as follows: 1) Although the duration of illness of smokers was longer than that of non-smokers, the smokers had significantly higher score of GAS and significantly lower score of PANSS than non-smokers at admission 2) With effects of age and duration of illness controlled, there were no differences of mean dosage of neuroleptics, extrapyramldal side effects, PANSS improvement rate and GAS improvement rate between both groups. 3) With effects of age, duration of illness, and total PANSS score controlled, there were no differences of score of SFM, cognitron, and FFA. 4) In smokers, the PANSS improvement rate and the GAS improvement rate were positively correlated with mean number of daily smoked cigarettes, with effects of age and duration of illness controlled. CONCLUSIONS: In schizophrenic patients, smokers had less severe symptoms than non-smokers. In smokers, the PANSS improvement rate and the GAS improvement rate were positively correlated with mean number of daily smoked cigarettes. But smokers were not proven to have received higher dosage of neuroleptics, to have lower extrapyramidal side effects, or to have less severe impairment of cognitive function.
Antipsychotic Agents ; Checklist ; Flicker Fusion ; Humans ; Schizophrenia ; Smoke* ; Smoking* ; Tobacco Products