Hyperopia is a refractive error, commonly called farsightedness, in which the EYE has difficulty focusing on near objects. Hyperopia results when the focal point of lightwaves entering the eye extends past the RETINA, causing the images the retina registers to be blurred. The refractive error occurs because the distance from the front to the back of the eye is shorter than normal. Symptoms of hyperopia include
CORRECTIVE LENSES (eyeglasses or contact lenses) can compensate for hyperopia by altering the focal point of lightwaves so it falls directly on the retina. They do so by refracting (bending) the lightwaves outward. REFRACTIVE SURGERY, which permanently alters the shape of the CORNEA, can provide refractive correction for people with mild to moderate hyperopia. Hyperopia sometimes occurs following refractive surgery for MYOPIA (nearsightedness) as a consequence of overcorrection. Eye professionals denote refractive corrections in units of measure called diopters. For hyperopia, the expression of diopter is a positive number. Corrective lenses for hyperopia have a magnifying appearance that make the eyes look bigger than they are.
Hyperopia is less common than myopia, affecting about 20 to 25 percent of adults. Few people who have hyperopia have greater than +6 diopters of refractive error, so nearly always corrective measures result in normal VISUAL ACUITY.
See also ASTIGMATISM; PRESBYOPIA; REFRACTIVE ERRORS.
Resource: Facts On File Encyclopedia Of Health And Medicine
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