Eye strain

Light therapy is an alternative treatment for depression associated with seasonal (e.g., winter) exacerbations. Possible side effects include eye strain, headache, insomnia, and hypo-mania.16,17 Also, potentially vulnerable patients, such as those with photosensitivity or a history of skin cancer, should be evaluated carefully prior to therapy.16... 

As a general rule 1000 particles are not required to obtain a statistical distribution unless the range of sizes varies over wide limits. For most measurements 200 particles are sufficient. The use of the filar micrometer is tedious and incurs serious eye-strain. To overcome this difficulty particles may be projected on a large ruled screen or grid. The particles will then be sufficiently large to be measured by eyw The use of photographs is also quite common. 

Eye strain can be responsible for frontal headaches. There may be occupational pointers, e.g. people using computers for long periods. Refer to an optometrist. Headache may also be a symptom of glaucoma if suspected, refer immediately to a doctor. 

Petroleum was used for many ills including coughs, bronchitis, pulmonary congestion, cramp, gout, rheumatism and eye strain. Modena petroleum was sold as far away as France, where it competed with local oils. 

There are microscopes with only one eye piece (monocular microscopes), which are useful for demonstrating to classes, but binocular microscopes with two eye pieces are more suitable for laboratories where a great deal of microscopic work is carried out, as they reduce eye strain. The eye piece is usually a lens giving a ten-fold magnification. In the case of a binocular microscope, the two eye piece lenses can be adjusted by the operator for the optimum distance between his or her eyes. 

The microscope should be set up for use as follows. The light source is switched on and the iris in the condenser is closed to its minimum. The height of the condenser is adjusted until the image of the iris appears in the microscope field this image is adjusted until it is central. The iris is then opened fully and the condenser is raised until maximal brightness is obtained. Whilst filters are not essential, some microscopes come supplied with a pale green filter which reduces glare and eye strain. 

The sensation produced by luminance within the visual field that is sufficiently greater than the luminance to which eyes are adapted to cause annoyance, discomfort, or loss in visual performance or ability (i.e., eye strain). 

The presence of vibrations can be detrimental to the performance of mental and physical tasks by humans. Low-frequency and large-amplitude vibrations contribute to problems such as headaches, motion sickness, eye strain, fatigue, and interference with the ability to read and interpret instruments [29]. These symptoms become less pronoimced as the frequency of vibration increases and the amplitude decreases. However, high-frequency and low-amplitude vibrations can also be quite fatiguing. 

As a construction worker, your hands, wrists, arms, shoulders, backs, and legs may be subjected to thousands of repetitive twisting, forcefiil, or fiexing motions dming a typical workday. Many construction jobs can expose you to excessive vibration and noise, eye strain, repetitive motion, and heavy hfting. 

Lighting and ventilation Use proper lighting in order to see your work clearly and reduce glare and eye strain. Use proper ventilation in order to carry away flying debris, fumes, vapors, and dust. 

Quality of Lighting The quality of lighting may affect error rates and cause accidents. For many applications control of illumination levels alone is not sufficient. Designs must control illumination quality as well. For example, users of computer screens are more likely to experience eye strain and other visual problems when there are combinations of poor reflectance, brightness ratio, and contrast ratio. 

Screens on computer monitors can also create work-related cases. Reflections of light sources on the screen can cause eye strain and visual errors. The reflected glare may result from reflections of nearby windows or overhead lighting. A user may adjust the head position that leads to fatigued neck and shoulder muscles or related effects. Some call this fanrily of cumulative disorders VDT (visual display terminal) syndrome or computer vision syndrome. Recent monitor designs reduce such problems through non-glare monitor surfaces. 

Contrast Ratio Contrast ratio refers to the intensity ratio between the darkest and lightest areas of a display. For a newspaper, the ratio between print and paper is 50 or more. Reading gray printon whiteorblackpaperis more difficult. Eye strain results if the ratio is too low. To prevent eye strain, computer screens should have the contrast properly adjusted. 

Every experiment consists of two parts, part 1 deals with the interaction between pattern and brain, and part 2 with the emotional self-assessment of each pattern. Fig. 11.8 shows a diagram of the slides used in the first part of the experiment, in which the brainwaves of every participant s response to each fabric were recorded. A preparation slide was first presented for 8 s then, a circle was shown with instructions of eye movements such as eyes close , eyes open and blink eyes , aiming at reducing eye strain during the experiment, followed by a grey screen between 2.5 and 3.5 s, which was set at the baseline period before presenting the actual fabric pattern stimulus for 11 s. This cycle was repeated four times. A 20 s break instruction followed on the screen, the circle then reappeared and this sequence was repeated... 

Lighting should be sufficient to enable people to work without experiencing eye strain and to safely move about. Provide artificial lighting if necessary. 

Some workers may experience fatigue, eye strain, upper limb disorders and backache from overuse or improper use of DSE. Upper limb disorders include problems of the arms, hands, shoulders and neck linked to work activities. These problems can also be experienced from poorly designed workstations or working environment. The cause may not be obvious and can be due to a combination of factors. 

Breaking up long spells of DSE work helps prevent fatigue, eye strain, upper limb disorders and back ache. The employer needs to plan so that users can interrupt prolonged use of DSE with changes of activity. Organised or scheduled rest breaks may sometimes be a solution. The following may help users ... 

Eye strain can be caused by subjecting the eye to excessively bright light, glare and is also a general term used for symptoms of refractive errors, uncorrected by spectacles, causing headaches, inflammation and general tiredness etc. 

Lighting is an important part of the work enviromnent. It has a direct impact on safety prevention of fatigue prevention of eye problems and product quality. Eye strain can be caused by subjecting the eye to bright light and glare. Eye strain may cause inflammation, headaches and general tiredness. 

There does not appear to be much medical evidence that DSE causes deterioration in eye sight, but many users suffer from visual fatigue which results in eye strain, sore eyes and headaches. Less common ailments are skin rashes and nausea. 

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