Longitudinal changes in critical flicker fusion frequency: an indicator of human workload

Invest. Ophthalmol. Vis. Sci.

Gerratt

Bassi

et al. 2017

PURPOSE. The purpose of this study was to determine whether subjects who wear short wavelength-blocking eyeglasses during computer tasks exhibit less visual fatigue and report fewer symptoms of visual discomfort than subjects wearing eyeglasses with clear lenses. METHODS.A total of 36 healthy subjects (20 male; 16 female) was randomized to wearing noblock, low-blocking, or high-blocking eyeglasses while performing a 2-hour computer task. A masked grader measured critical flicker fusion frequency (CFF) as a metric of eye fatigue and evaluated symptoms of eye strain with a 15-item questionnaire before and after computer use. RESULTS.We found that the change in CFF after the computer task was significantly more positive (i.e., less eye fatigue) in the high-block versus the no-block (P ¼ 0.027) and low-block (P ¼ 0.008) groups. Moreover, random assignment to the high-block group but not to the low-block group predicted a more positive change in CFF (i.e., less eye fatigue) following the computer task (adjusted b ¼ 2.310; P ¼ 0.002). Additionally, subjects wearing high-blocking eyeglasses reported significantly less feeling pain around/inside the eye (P ¼ 0.0063), less feeling that the eyes were heavy (P ¼ 0.0189), and less feeling that the eyes were itchy (P ¼ 0.0043) following the computer task, when compared to subjects not wearing high-blocking lenses. CONCLUSIONS.Our results support the hypothesis that short-wavelength light-blocking eyeglasses may reduce eye strain associated with computer use based on a physiologic correlate of eye fatigue and on subjects' reporting of symptoms typically associated with eye strain.

Section: Critical Flicker Fusion Frequency (Cff) Measurements and Eyementioning

confidence: 99%

Short-Wavelength Light-Blocking Eyeglasses Attenuate Symptoms of Eye Fatigue

Invest. Ophthalmol. Vis. Sci.

Gerratt

Bassi

et al. 2017

“…Critical fusion frequency is a recognised metric indicative of fatigue and workload . Reduction in critical fusion frequency is associated with eye fatigue . Critical fusion frequency was tested using a Handy Flicker device (Handy Flicker HF‐II, Neitz, Tokyo, Japan).…”

Section: Methodsmentioning

confidence: 99%

“…These symptoms include eye irritation, blurred vision, eye strain, double vision, and headache, and are now known collectively as ‘computer vision syndrome’, which affects the ability to comfortably perform visual tasks . Factors associated with computer vision syndrome, such as lighting, glare, and fatigue, have been investigated, but few studies have considered the interactive effects of these factors.…”

mentioning

confidence: 99%

The effects of reflected glare and visual field lighting on computer vision syndrome

Clinical and Experimental Optometry

Yeh

et al. 2019

Background Computer vision syndrome is common and affects performance of visual tasks. Background illumination, light source, light compensation, position of the display, contrast and glare are environmental factors associated with computer vision syndrome. The aim of this study is to investigate the effects of reflected glare and visual field lighting on computer vision syndrome. Methods In a reflected glare experiment, participants performed a two‐hour visual task using a glossy, matte, or glare‐free surface display in two visual environments (normal, glare). In a visual field lighting experiment, participants performed the visual task in dim lighting, uneven supplementary lighting, or uniform supplementary lighting. Visual function parameters, including critical fusion frequency, heterophoria, amplitude of accommodation and accommodative facility were evaluated by the investigators and a visual fatigue questionnaire was completed before and after the visual task. Visual performance was also recorded. In addition, the variation of pupil size under different lighting conditions was analysed. Results Critical fusion frequency was the only visual function parameter which decreased significantly after the visual task. The questionnaire score was significantly higher in a glare environment and was lower when the task was performed using a glare‐free display. Visual performance was significantly worse in the glossy display group. The increment in the questionnaire score was smaller in the uniform supplementary lighting group. Visual performance was significantly worse in the dim lighting or uneven supplementary lighting group, but not in the uniform supplementary lighting group. Variation in pupil size was significantly greater in the dim lighting condition than in the supplementary lighting condition. Conclusion Critical fusion frequency is an effective indicator of computer vision syndrome. Glare‐free displays could alleviate visual fatigue and preserve visual performance. Uniform supplementary lighting could decrease variation in pupil size and prevent eye strain.

“…In the current study, critical fusion frequency (CFF) is used to measure eyestrain. CFF, a function of the retina, is the level of sensitivity at the beginning and at the end of a series of light flashes (Luczak & Sobolewski, 2005). As a measurement tool, CFF, a function of the degree and intensity of light, is highly sensitive and easy to use (Kang, Wang, & Lin, 2009).…”

Section: The Work Characteristics Of Ic Reworkingmentioning

confidence: 99%

Predicting visual fatigue in integrated circuit packaging plants

Liang

Hwang

et al. 2010

Hum Ftrs & Erg Mfg Svc

In the reworking department of integrated circuit (IC) production, both inspection and repair are visual tasks, and reworking operators frequently complain about eyestrain problems that lead to human error and a low yield rate. In this study, we evaluate the relationship between the operators' visual fatigue and actual defect data gathered from May to June 2008 and find a positive relationship between visual fatigue and the number of defects. To prevent eyestrain overload, we develop a visual fatigue prediction model using as significant predictors working time, rest time, number of inspections, number of repairs, and task difficulty. After the model was implemented in a real workplace, both visual comfort and yield rate improved. C 2010 Wiley Periodicals, Inc.