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Corrective lens. A pair of contact lenses, positioned with the concave side facing upward. 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.
Progressive lenses are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearer's correction for the other refractive errors. The gradient starts at the wearer's distance prescription at the top of the lens and reaches a ...
The PALS grid is easily visible in this image of the US Marine Corps' Interceptor Body Armor; note the pouches attached to the system in the background (2005). The Pouch Attachment Ladder System or PALS is a grid of webbing invented and patented by United States Army Natick Soldier Research, Development and Engineering Center used to attach smaller equipment onto load-bearing platforms, such ...
Pediatric advanced life support. Pediatric advanced life support (PALS) is a course offered by the American Heart Association (AHA) for health care providers who take care of children and infants in the emergency room, critical care and intensive care units in the hospital, and out of hospital (emergency medical services (EMS)).
Astigmatism (optical systems) An optical system with astigmatism is one where rays that propagate in two perpendicular planes have different foci. If an optical system with astigmatism is used to form an image of a cross, the vertical and horizontal lines will be in sharp focus at two different distances. The term comes from the Greek α- (a ...
Lens case to store contacts Contact lenses soaking in a hydrogen peroxide-based solution. The case is part of a "one-step" system and includes a catalytic disc at the base to neutralise the peroxide over time. Lens care varies depending on material and wear schedule. Daily disposables are discarded after a single use and thus require no cleaning.
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis.
Barlow lens. The Barlow lens, named after Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components that are after it in the system. The practical result is that inserting a Barlow lens magnifies the image.