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Vertex distance is the distance between the back surface of a corrective lens, i.e. glasses (spectacles) or contact lenses, and the front of the cornea. Increasing or decreasing the vertex distance changes the optical properties of the system, by moving the focal point forward or backward, effectively changing the power of the lens relative to ...
A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.
The incidence of eye injuries during general anaesthesia has been studied, and different methods of eye protection have been compared. [citation needed] When eyes are untaped during general anaesthesia, the incidence of ocular injury has been reported to be as high as 44%. [1][2] If tape is used to hold the eyes closed, ocular injury occurs ...
Frequency. ~20% [5] Dry eye syndrome, also known as keratoconjunctivitis sicca, is the condition of having dry eyes. [2] Symptoms include dryness in the eye, irritation, redness, discharge, blurred vision, and easily fatigued eyes. Symptoms range from mild and occasional to severe and continuous. [3]
An eye chart is a chart used to measure visual acuity comprising lines of optotypes in ranges of sizes. Optotypes are the letters or symbols shown on an eye chart. [ 1 ] Eye charts are often used by health care professionals, such as optometrists , physicians and nurses , to screen persons for vision impairment .
European respirator standards. The European respirator standards refer to the filtering classification by EN 149, EN 14683, and EN 143, all European standards of testing and marking requirements for respirators. [1] FFP standard masks (where FFP stands for filtering facepiece) [2] cover the nose, mouth and chin and may have inhalation and/or ...
Eye protection. An airman using a welding mask. Failing to use proper eye protection when welding may lead to blindness. Eye protection is protective gear for the eyes, and sometimes face, designed to reduce the risk of injury. Examples of risks requiring eye protection can include: impact from particles or debris, light or radiation, wind ...
Glasses, also known as eyeglasses and spectacles, are vision eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms, known as temples or temple pieces, that rest over the ears. Man with glasses. Glasses are typically used for vision ...
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