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Work-Related Ill Health
Published in Céline McKeown, Office Ergonomics and Human Factors, 2018
Typical symptoms of eye fatigue include redness of the eyes, itching in the eyes, blurred vision, double vision, aching around the eyes, watering eyes, headaches, and, sometimes, nausea. The symptoms are considered to be caused by overuse of the muscles around the eyes, which are responsible for positioning and controlling the eye as people read the screen, look at the keyboard, and refer to documents. If an individual works for long periods without interruption, the muscles of the eye become fatigued like any other muscle in the body. The main causes of visual fatigue are poor screen positioning relative to overhead lights and windows, glare, inappropriate viewing distances, badly designed screen displays with characters that are difficult to read, unsuitable environmental conditions that result in dry air, extended screen work without interruption and intense concentration. When people work for long periods and are concentrating on their work without interruption, they tend to stop blinking or do not blink as frequently. Blinking is a reflex action that should occur every two to ten seconds. The purpose of blinking is to remove debris from the surface of the eye, such as dust particles, and to moisten the eye. Once an individual starts to concentrate on their work, their blink rate drops and their eyes start to dry; this is accompanied by a build-up of dust particles, which makes the eye feel uncomfortable.
The Visual Environment: Measurement and Design
Published in R. S. Bridger, Introduction to Human Factors and Ergonomics, 2017
Blinking is a reflex action that occurs every 2–10 s. It is also a voluntary, forced closure of the eye. The function of blinking is to stimulate tear production and flush out foreign objects (such as dust particles) from the surface of the eye. Tears, a dilute saline solution, lubricate eye movements and are mildly bactericidal. The eye is covered with a precorneal tear film (PTF) that protects it from the outer environment (Wolkoff et al., 2004). The PTF consists of an outer lipid layer covering a water layer, below which is a layer of mucin. Eye blinking and tear production are essential for the maintenance of the PTF. Blinking is divided into three categories: Voluntary blinking—a conscious decision to close the eyesInvoluntary blinking—at a frequency of approximately 12–20 blinks/min in subjects at restReflex blinking—in response to mainly visual and ocular stimuli
Sensor- and Recognition-Based Input for Interaction
Published in Julie A. Jacko, The Human–Computer Interaction Handbook, 2012
In the context of recognition, a feature can refer to a particular sensor or a piece of information derived from one or more sensors, or even derived from other features. Often thought of as a preprocessing step, feature selection refers to the process of determining which features are to be computed from the raw inputs and passed to the next level of processing. Appropriate feature selection can sometimes make difficult recognition problems easy. For example, one somewhat unusual approach to detecting faces in video is to detect eye-blinking patterns. Blinking provides a signal that is easily detected by simple image-processing operations, and is further supported by the fact that both eyes blink together and are arranged in a symmetric spatial configuration on the face. Blinking thus may be highly diagnostic for faces (Crowley and Berard 1997).
Accommodative asthenopia among Romanian computer-using medical students—A neglected occupational disease
Published in Archives of Environmental & Occupational Health, 2020
Horatiu-Remus Moldovan, Septimiu-Toader Voidazan, Gabriela Moldovan, Maria-Ancuta Vlasiu, Geanina Moldovan, Roxana Panaitescu
Symptoms like dry eyes, stinging, and burning sensation can be attributed to insufficient blinking. Normally people blink about 20–22 times per minute, but while working at a computer the blinking rate is decreased to 4–6 times per minute, which can cause the evaporation of the protective liquid from the corneal surface. Sitting in front of a computer for an extended period is another stressor that can cause dry eye syndrome which can lead to headaches by forcing people to arch their foreheads in an effort to see better.15