Such a change usually accompanies the development of some cataracts. As a result there is an increase in refractive power. Lenticular myopia Myopia attributed to an increase in the index of refraction of the lens. Juvenile-onset myopia late-onset myopia See acquired myopia. Instrument myopia A temporary increase in accommodation induced by looking through an optical instrument. Hypertonic myopia See spasm of accommodation. See open-angle glaucoma high index lens pathological myopia. High myopia Myopias above 6.0 D or more are usually considered as high myopias. It may occur as a result of a pathological condition, such as cataract, vitreous haemorrhage, ptosis, eyelid closure, or in inordinately long occlusion therapeutic sessions. None has yet been found to be reliably effective.ĭegenerative myopia See pathological myopia.įorm-deprivation myopia Myopia developing in children when the retina is stimulated by a blurred image during the critical period of development. They include bifocals, contact lenses, pharmaceutical agents, incorrect single vision lenses (undercorrection, overcorrection), vision therapy and feedback strategies. Myopia control Term used to encompass the various methods aimed at slowing or arresting the progression of myopia. Those myopias developing in the late teens and adulthood are usually referred to as late-onset myopia (or adult-onset myopia), whereas those occurring earlier are often referred to as early-onset myopia (or juvenile-onset myopia). See gene-environment interaction photorefractive keratectomy orthokeratology pseudomyopia lattice degeneration of the retina Marfan's syndrome use-abuse theory.Īcquired myopia Myopia appearing after infancy, or in adulthood. The percentage of myopes in Caucasian populations is about 24-28%, it is much higher among Chinese (70-80%).
In myopia the point conjugate with the retina, that is the far point of the eye, is located at some finite point in front of the eye (Fig. Refractive condition of the eye in which the images of distant objects are focused in front of the retina when the accommodation is relaxed. In addition, contacts do not steam up from perspiration or changes in temperature. Contact lenses offer several benefits over glasses, including: better vision, less distortion, clear peripheral vision, and cosmetic appeal. It is very important to follow the cleaning and disinfecting regimens prescribed because protein and lipid buildup can occur on the lenses, causing discomfort or increasing the risk of infection. While oxygen passes freely through soft lenses, bacterial contamination and other problems can occur, requiring replacement of lenses on a regular basis. Soft lenses offer increased comfort and the advantage of extended wear some can be worn continuously for up to one week. Soft contact lenses are made of flexible plastic and can be up to 80% water. Rigid gas permeable lenses offer crisp, clear, sight. A procedure called orthokeratology acts on this principle of "corneal molding." However, when contact lenses are discontinued for a period of time, the cornea will generally go back to its original shape.
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