Search results
Results From The WOW.Com Content Network
Childhood cataract is cataract that occurs at birth or in childhood. [1] It may be congenital or acquired. Congenital cataracts are defined as the presence of lens opacification during childhood. [2] About 1.14 million children in the world are blind. [3] Cataracts are the leading cause of blindness in children. [4]
This test can be used for routine ocular screening by nurses, pediatricians, family practitioners, and optometrists. Retinoscopy through the child's undilated pupil is helpful for assessing the potential visual significance of an axial lens opacity in a pre-verbal child. Any central opacity or surrounding cortical distortion greater than 3 mm ...
A-scan ultrasound biometry, commonly referred to as an A-scan (short for Amplitude scan), uses an ultrasound instrument for diagnostic testing. [1] A-scan biometry measures the axial length (AL) of the eye prior to cataract surgery in order to assess the refractive power of the intraocular lens that will be implanted.
The most common method of classifying the shapes of aberration maps is to consider each map as the sum of fundamental shapes or basis functions. One popular set of basis functions are the Zernike polynomials. [2] Each aberration may be positive or negative in value and induces predictable alterations in the image quality. [9]
The analyser will provide a lens strength and type (either spherical and/or cylindrical), if required for the test. In these instances, wire-rimmed trial lenses are generally used, with the cylindrical lens placed closest to the patient so the axis is easily read. The clinician can alter the fixation targets as per necessary (see Fixation ...
A lens is made of two curved surfaces, and an aspheric lens is a lens where one or both of those surfaces is not spherical. Further research and development is being conducted [ citation needed ] to determine whether the mathematical and theoretical benefits of aspheric lenses can be implemented in practice in a way that results in better ...
A cataract is an opacity that develops in the crystalline lens of the eye. [9] The word cataract literally means, "curtain of water" or "waterfall" as rapidly running water turns white, so the term may have been used metaphorically to describe the similar appearance between mature ocular opacities and water fall.
Cataracts are the greying or opacity of the crystalline lens, which can be caused in children by intrauterine infections, metabolic disorders, and genetically transmitted syndromes. [56] Cataracts are the leading cause of child and adult blindness that doubles in prevalence with every ten years after the age of 40. [ 57 ]