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a defect of vision in which parallel light rays reaching the eye come to focus behind the retina, vision being better for distant objects than for near. Called also farsightedness.

Most children are born with some degree of farsightedness. As the child grows this decreases and usually disappears by the age of 8 years. If the child is excessively farsighted, however, the constant effort to focus may cause headaches and fatigue. Eyeglasses used to correct hyperopia are convex; that is, they bend the light rays toward the center, helping the lens of the eye to focus them on the retina.
Refraction and correction in hyperopia. From Ignatavicius and Workman, 2002.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


A gene on chromosome 3q28-q29 that encodes a DNA-binding repressor of genes that require a basic helix-loop-helix (bHLH) for their transcription. This transcription repression requires the formation of a complex with a co-repressor protein of the Groucho/TLE family. HES1 is thought to downregulate myogenesis by inhibiting the functions of MYOD1 and ASH1, and may play a role in a functional FA core complex response to DNA cross-link damage.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.