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In cases of accommodative esotropia, the eyes turn inward due to the effort of focusing far-sighted eyes, and the treatment of this type of strabismus necessarily involves refractive correction, which is usually done via corrective glasses or contact lenses, and in these cases surgical alignment is considered only if such correction does not ...
The company made small bull's-eye lenses for use on railroads, steamboats, and docks; [56] such lenses were common in the United States by the 1870s. [ 13 ] : 488 In 1858 the company produced "a very small number of pressed flint-glass sixth-order lenses" for use in lighthouses—the first Fresnel lighthouse lenses made in America. [ 56 ]
Conceptual rendering of the effect of color corrective lenses. Color blind glasses or color correcting lenses are light filters, usually in the form of glasses or contact lenses, that attempt to alleviate color blindness, by bringing deficient color vision closer to normal color vision or to make certain color tasks easier to accomplish.
When refractive errors in children are not treated, the child may be at risk of developing ambylopia, where vision may remain permanently blurry. [30] Because young children typically do not complain of blurry vision, the American Academy of Pediatrics recommends that children have yearly vision screening starting at three years old so that unknown refractive errors or other ophthalmic ...
Horror fusionis is a rare condition and normally appears only in patients who have been treated by means of surgery or other interventions. [2] Attempts to achieve stereoscopic vision, in particular anti-suppression therapy and other orthoptic exercises, may lead to double vision as undesired side effect, in particular also to horror fusionis.
The Washington Post suggested, "It is possible that the conflict between the PRISM slides and the company spokesmen is the result of imprecision on the part of the NSA author. In another classified report obtained by The Post, the arrangement is described as allowing 'collection managers [to send] content tasking instructions directly to ...
A simplest case is where thin lenses are placed in contact (=). Then the combined focal length f of the lenses is given by = +. Since 1/f is the power of a lens with focal length f, it can be seen that the powers of thin lenses in contact are additive. The general case of multiple thin lenses in contact is
A contact lens (also known simply as a contact) is a corrective, cosmetic, or therapeutic lens usually placed on the cornea of the eye. Modern soft contact lenses were invented by the Czech chemist Otto Wichterle and his assistant Drahoslav Lím , who also invented the first gel used for their production.