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Purpose: Critical flicker‐fusion frequency (CFF) has been used in clinical studies as a measure of visual fatigue. We examine the correlation between CFF and subjective reports of visual fatigue in a group of symptomatic computer users, to consider whether CFF may be used as a surrogate measure of visual fatigue symptoms. Methods: We analysed data from a previous randomised controlled trial. One hundred and twenty adults, diagnosed with computer vision syndrome, had CFF and visual fatigue symptoms quantified before and after a visually demanding 2‐h computer task. Symptoms were assessed using a questionnaire with nine subcomponents that summed to a total score of 900. CFF was measured using a two‐interval forced‐choice method, with the flicker rate altered by a computer‐controlled staircase procedure. For our primary analysis, we determined Spearman correlation coefficients between post‐task symptom scores and CFF, and between change from baseline symptom scores and CFF. We also used a bootstrap procedure to consider whether symptom score subcomponents were significantly (Bonferroni‐corrected) different from overall scores with regard to their correlations with CFF. Results: Although visual fatigue symptom scores altered significantly post‐task (mean change: 92 units; 95% confidence interval [CI]: 11 to 122), CFF did not (mean change −0.7 Hz; 95% CI: −1.7 to 0.3). There was no significant correlation between overall symptom scores and CFF, either for the post‐task (r = −0.13; 95% CI: −0.31 to 0.05) or the change from baseline (r = −0.18; 95% CI: −0.35 to 0.01) analysis. Subcomponents of the symptom questionnaire did not show a significant correlation with CFF, either for the post‐task or the change from baseline analysis. Conclusions: We find that CFF is not a useful surrogate for symptoms of visual fatigue, given its low correlation with scores on a visual fatigue symptom questionnaire. [ABSTRACT FROM AUTHOR]

This study aims to examine the benefit of visual fatigue evaluation based on prefrontal cortex (PFC) measurement by near infrared spectroscopy (NIRS), and to evaluate fatigue on various colored LED backlit text. In our method, eight adult participants read a LED backlit text 10 minutes in a dark room. Before and after task, subjective fatigue questionnaire “Jikaku-sho shirabe”, subjective visual fatigue questionnaire (SVF), and the critical flicker-fusion frequency (CFF) were measured. The time-course of oxy-Hb in the PFC was measured using a 22-channel NIRS. Heart rate variability (HRV) was measured to access an autonomic nervous system balance. Six types of white LEDs were used for backlighting: general white as a control (W), high color-rendering white (WH), bluish white (WB), reddish white (WR), greenish white (WG), and yellowish white (WY). In our results, correlation analysis suggested that the development of central fatigue is related to deactivated condition in the mPFC, and the development of subjective visual fatigue is related to deactivated condition in the LPFC. In comparison between LED treatments, in WH condition, high subjective central fatigue, CFF decay and LF/HF were revealed, and the PFC inactivated. In WG condition, low subjective central fatigue and CFF decay revealed. Our findings suggested that participants get tired on high color-rendering white LED backlit text, and were less tired in greenish white LED backlit text. Also, NIRS provides benefits in the evaluation of visual fatigue.

• Mouse critical flicker fusion frequency (CFF) was estimated by behavioral performance using an operant system. • Two different types of psychological methods were employed, the ascending method of limit and method of constant stimuli. • We estimated the mouse CFF to be about 14 Hz. • Our results highlight the usefulness of the operant conditioning method for measuring mouse visual temporal resolution. The critical flicker-fusion frequency (CFF), defined as the frequency at which a flickering light is indistinguishable from a continuous light, is a useful measure of visual temporal resolution. The mouse CFF has been studied by electrophysiological approaches such as recordings of the electroretinogram (ERG) and the visually evoked potential (VEP), but it has not been measured behaviorally. Here we estimated the mouse CFF by using a touchscreen based operant system. The test with ascending series of frequencies and that with randomized frequencies resulted in about 17 and 14 Hz, respectively, as the frequency which could not be distinguished from steady lights. Since the ascending method of limits tend to overestimate the threshold than the descending method, we estimated the mouse CFF to be about 14 Hz. Our results highlight usefulness of the operant conditioning method in measurement of the mouse visual temporal resolution. [ABSTRACT FROM AUTHOR]

Background: Quercetin is one of the dietary flavonoids found in citrus fruits and leafy vegetables as well as seeds and green tea. Its name comes from Quercetum and belongs to flavonol class which is not synthesized in the human body. Many studies revealed a significant effect of quercetin in advancing psychomotor/cognitive performances and reversing the neurotoxin-induced neuronal damage. Therefore, the present study aimed to illustrate the central effect of quercetin on human vigilance and in normal healthy volunteers. Subjects and Methods: A total of fifty healthy volunteers with a mean age of 23 years were enrolled in this experimental study; they were divided into two groups: Group I: twenty healthy volunteers treated with placebo (500 mg/day starch capsule) for 2 weeks and Group II: thirty healthy volunteers treated with quercetin 500 mg/day for 2 weeks. Each volunteer in each group was subjected to vigilance-psychomotor testing by Leeds psychomotor performance tester which measures Psychomotor-vigilance test (PVT) and Cortical arousal activity (CAA). Results: Quercetin produced a more significant effect on total reaction time, recognition reaction time, movement reaction time, fusion index, % fusion (P < 0.01), and flicker percentage (P < 0.05) compared to control, but quercetin produced an insignificant effect on CFFd, critical flicker-fusion frequency, and flicker index. Conclusion: Quercetin improves psychomotor performance and CAA in normal healthy volunteers. [ABSTRACT FROM AUTHOR]

Background: Trimetazidine is a fatty oxidation inhibitor, leading to shifting of energy substrate from fatty acid oxidation toward glucose oxidation that leads to the reduction of oxygen requirement. The aims of the present study were to elucidate the effects of trimetazidine on psychomotor performance and vigilance on normal healthy volunteers. Materials and Methods: A total of 234 subjects (age 22–25 years) were recruited in this study. The volunteers were randomizing into two groups with 117 volunteers in each group. Group I received an inert starch capsule served as a control, and Group II received trimetazidine tablet 15 mg/day. The duration of therapy was 5 days. Test procedure was done at 9.00 a.m. on the psychomotor tester. Before the drug administration, prescore values were recorded and then after 5 days of therapy, the postscore values were recorded. Results: The placebo did not demonstrate a significant effect on all psychomotor performances and flicker-fusion elements (P > 0.05). Trimetazidine therapy produced a highly significant effect on all components of psychomotor performances and flicker-fusion parameters (P < 0.001) compared with pretreatment era. Conclusion: We conclude that trimetazidine improves psychomotor performance and vigilance in normal healthy volunteers through advancing total reaction time and critical flicker-fusion frequency.

To assess the influence of age-related macular degeneration (AMD) on critical flicker-fusion frequency (CFF). CFF was measured centrally for a red, green and blue target, and in 10° excentricity with a red target. Twenty-eight patients with non-exsudative AMD, 12 patients with exsudative AMD and 45 age-matched healthy eyes were included. CFF decreased in eyes with non-exsudative AMD (red 1.3 Hz, p = 0.025; green 1.4 Hz, p = 0.053; blue 2.1 Hz, p = 0.006) and exsudative AMD (red 2.2 Hz, p = 0.02; green 3.3 Hz, p = 0.001; blue 2.9 Hz, p = 0.02). The difference between central and peripheral CFF increased in non-exsudative AMD (red–red 10°, 0.7 Hz, p = 0.024), but was not significantly increased in exsudative AMD (1.3 Hz, p = 0.059). There was no difference between eyes with non-exsudative AMD with good visual acuity (VA >20/32, n = 18) and healthy eyes, nor between eyes with non-exsudative ( n = 10) and exsudative AMD ( n = 9) with VA from 20/100 to 20/40. CFF decreased in non-exsudative and exsudative AMD. CFF is not able to distinguish between AMD eyes and healthy eyes of equal visual acuity, and therefore is not applicable as a possible diagnostic test. [ABSTRACT FROM AUTHOR]

Critical flicker-fusion frequency (CFF) has often been applied to psychotropic drug evaluation as a measure of cortical arousal. There are several variables that must be considered for proper conclusions to be obtained from CFF experimental data. Psychological variables such as subject response bias are especially difficult to control. We studied the effects of single oral doses of 10 mg diazepam and 10 mg amphetamine sulfate on CFF values obtained by a block up-down spatial forced-choice method on 13 healthy volunteers (seven males and six females). Signal detection theory was also used to obtain the non-parametric value P(A) as a measure of sensory function and B as a measure of the psychological function of response bias. As a group, amphetamine increased CFF (Hz) and P(A) and diazepam decreased CFF (Hz) and P(A), with the most significant effects observed at 2 and 3 h after drug administration. B scores showed more individual variation with a trend towards a low score, or a tendency to report more flicker responses after diazepam. Separated by sex, the males had a higher percentage of subjects that demonstrated a reduction of CFF after diazepam, while the females had a higher percentage that demonstrated an increase in CFF after amphetamine. The results suggest that CFF changes following diazepam and amphetamine are mostly changes in sensory function and not changes in response bias. It is possible to apply detection theory to flicker-fusion studies and the accounting of bias by controlling, measuring or eliminating it is essential in interpretation of CFF data. [ABSTRACT FROM AUTHOR]

Background: Trimetazidine is a fatty oxidation inhibitor, leading to shifting of energy substrate from fatty acid oxidation toward glucose oxidation that leads to the reduction of oxygen requirement. The aims of the present study were to elucidate the effects of trimetazidine on psychomotor performance and vigilance on normal healthy volunteers., Materials and Methods: A total of 234 subjects (age 22-25 years) were recruited in this study. The volunteers were randomizing into two groups with 117 volunteers in each group. Group I received an inert starch capsule served as a control, and Group II received trimetazidine tablet 15 mg/day. The duration of therapy was 5 days. Test procedure was done at 9.00 a.m. on the psychomotor tester. Before the drug administration, prescore values were recorded and then after 5 days of therapy, the postscore values were recorded., Results: The placebo did not demonstrate a significant effect on all psychomotor performances and flicker-fusion elements ( P > 0.05). Trimetazidine therapy produced a highly significant effect on all components of psychomotor performances and flicker-fusion parameters ( P < 0.001) compared with pretreatment era., Conclusion: We conclude that trimetazidine improves psychomotor performance and vigilance in normal healthy volunteers through advancing total reaction time and critical flicker-fusion frequency., Competing Interests: There are no conflicts of interest.