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When refractive errors in children are not treated, the child may be at risk of developing ambylopia, where vision may remain permanently blurry. [33] 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 ...
Global refractive errors have been estimated to affect 800 million to 2.3 billion. [128] The incidence of myopia within sampled population often varies with age, country, sex, race , ethnicity , occupation, environment, and other factors.
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Amblyopia: is a category of vision loss or visual impairment that is caused by factors unrelated to refractive errors or coexisting ocular diseases. [59] Amblyopia is the condition when a child's visual systems fail to mature normally because the child either has been born premature, measles, congenital rubella syndrome, vitamin A deficiency ...
The prevalence of astigmatism increases with age due to changes in refractive index gradients. [33] [34] According to an American study, nearly three in ten children (28.4%) between the ages of five and seventeen have astigmatism. [35] A Brazilian study published in 2005 found that 34% of the students in one city were astigmatic. [36]
In normal population the dominant aberrations are the ordinary second-order spherocylindrical focus errors, which are called refractive errors.Higher order aberrations are a relatively small component, comprising about 10% of the eye's total aberrations. [3]
Retinoscopy is particularly useful in prescribing corrective lenses for patients who are unable to undergo a subjective refraction that requires a judgement and response from the patient (such as children or those with severe intellectual disabilities or communication problems).
The majority of autorefractors calculate the vision correction a patient needs (refraction) by using sensors that detect the reflections from a cone of infrared light. These reflections are used to determine the size and shape of a ring in the retina which is located in the posterior part of the eye.