- Impaired vision in an eye due to a disorder of the brain cells that control the vision in that eye, not usually due to a problem with the eye itself. Amblyopia is caused by lack of use of an eye when the brain favors the other eye. The eye is different in a way to cause this preference. The term "amblyopia" is sometimes incorrectly used interchangeably with lazy eye. "Amblyopia" is made up of ambly- + -opia. Ambly- is from the Greek amblys meaning blunt, dull, faint, or dim. The suffix -opia also comes from the Greek, from ops meaning eye, and refers to vision, So amblyopia is, literally, dim vision. The most common causes of amblyopia are strabismus and anisometropia. In strabismus, the eyes are not aligned. The brain favors one eye over the other and the ignored eye is not adequately stimulated and the visual brain cells do not mature normally. Anisometropia occurs when the eyes have an unequal refractive power. One eye is myopic (nearsighted) and the other hyperopic (farsighted). Because the brain cannot reconcile this difference, it develops a preference for the image coming from one eye only. Other causes of amblyopia include ptosis (drooping) of the eyelid, congenital cataract, and eye trauma. The treatment of each cause of amblyopia is different. Nocturnal amblyopia is night blindness.
* * *Poor vision caused by abnormal development of visual areas of the brain in response to abnormal visual stimulation during early development. [G. a., dimness of vision, fr. amblys dull, + ops, eye]- anisometropic a. a suppression of central vision due to an unequal refractive error (anisometropia) of at least two diopters. This induces a sufficient difference in image size (aniseikonia) that the two images cannot be fused. In order to avoid confusion, the blurrier image is suppressed. SYN: refractive a..- a. ex anopsia SYN: suppression a..- meridional a. a. due to an uncorrected, large astigmatism during the amblyogenic period of visual development.- nutritional a. a. resulting from lack of vitamin B–complex constituents.- pattern distortion a. a. due to a blurred retinal image during the amblyogenic period of visual development.- sensory a. a suppression of central vision in an eye due to poor image formation; e.g., by a corneal scar, a cataract, or a droopy eyelid. SYN: deprivation a..- strabismic a. a suppression of central vision due to the two eyes pointing in different directions. The two scenes cannot be fused into a single image, so, to avoid confusion, one of the images is suppressed.- suppression a. suppression of the central vision in one eye when the images from the two eyes are so different that they cannot be fused into one. This may be due to: 1) faulty image formation (sensory a.); 2) a large difference in refraction between the two eyes (anisometropic a.); or 3) the two eyes pointing in different directions (strabismic a.). Most suppression a. can be reversed if appropriately treated before age 6 years. SYN: a. ex anopsia.- tobacco-alcohol a. an acquired optic neuropathy particularly involving the maculopapillary bundle nerve fibers associated with excessive alcohol and tobacco consumption.
* * *am·bly·opia .am-blē-'ō-pē-ə n dimness of sight esp. in one eye without apparent change in the eye structures called also lazy eye, lazy-eye blindnessam·bly·opic -'ō-pik, -'äp-ik adj
* * *n.poor sight, not due to any detectable disease of the eyeball or visual system, known colloquially as lazy eye. In practice this strict definition is not always obeyed. For example, in toxic amblyopia, caused by tobacco, alcohol, certain other drugs, and vitamin deficiency, there is a disorder of the optic nerve. The commonest type is amblyopia ex anopsia, in which factors such as squint (see strabismus), cataract, and other abnormalities of the optics of the eye (see refraction) impair its normal use in early childhood by preventing the formation of a clear image on the retina.
* * *am·bly·o·pia (am″ble-oґpe-ə) [ambly- + -opia] impairment of vision due to abnormal development, without detectable organic lesion of the eye. Cf. amaurosis. amblyopic adj
Medical dictionary. 2011.