| refractive | Serving or having power to refract, or turn from a direct course; pertaining to refraction; as, refractive surfaces; refractive powers. Refractive index. <medicine> The ratio of the sine of the angle of incidence to the sine of the angle of refraction for a ray passing out of one of the media into the other. Origin: Cf. F. Refractif. See Refract. Source: Websters Dictionary (01 Mar 1998) |
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| refractive accommodative esotropia | That type of esotropia eliminated by correction of hypermetropic refractive error. (05 Mar 2000) |
| refractive amblyopia | 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. Synonym: refractive amblyopia. (05 Mar 2000) |
| refractive errors | Deviations from the average or standard indices of refraction of the eye through its dioptric or refractive apparatus. (12 Dec 1998) |
| refractive index | <microscopy> The ratio of the velocity of light in a vacuum to the velocity in some medium. Refractive index generally increases with the atomic number of the constituent atoms. (05 Aug 1998) |
| refractive keratoplasty | Any procedure in which the shape of the cornea is modified, with the intent of changing the refractive error of the eye; for example, if the cornea is flattened, the eye becomes less myopic. See: photorefractive keratectomy, keratophakia, lamellar keratoplasty, thermokeratoplasty, keratomileusis, radial keratotomy. Synonym: keratorefractive surgery. (05 Mar 2000) |
| refractive keratotomy | Modification of corneal curvature by means of corneal incisions to minimise hyperopia, myopia, or astigmatism.In this type of radial keratotomy surgery, performed by excimer laser, pie-shaped pieces of cornea are removed under local anaesthetic. The resulting scar tissue formation reshapes the cornea. This class of surgery is somewhat unpredictable, and its long-term effects are still unknown. (05 Mar 2000) |
| abrasive media | <microscopy> Extremely hard materials (Diamond, SiC, Al2O3 etc.), usually in a very fine particulate form (less than 15 micrometres), used in the initial stages of specimen preparation to grind and polish samples to the desired thickness or finish. (05 Aug 1998) |
| aerotitis media | See Aerotitis. (12 Dec 1998) |
| arteria cerebri media | <anatomy, artery> One of the two large terminal branches (with anterior cerebral artery) of the internal carotid artery; it passes laterally around the pole of the temporal lobe, then posteriorly in the depth of the lateral cerebral fissure; for descriptive purposes it is divided into three parts: 1) the sphenoidal part (M1 segment of clinical terminology), supplying perforating branches to the internal capsule, thalamus, and striate body; 2) the insular part, supplying branches to the insula and adjacent cortical areas; and 3) the terminal part or cortical part, supplying a large part of the central cortical convexity (the latter two collectively forming M2 segment). Synonym: arteria cerebri media. (05 Mar 2000) |
| arteria colica media | <anatomy, artery> Origin, superior mesenteric; distribution, transverse colon; anastomoses, right and left colic. Synonym: arteria colica media. (05 Mar 2000) |
| arteria collateralis media | <anatomy, artery> The posterior terminal branch of the profunda brachii, anastomosing with the arteries which form the articular network of the elbow. Synonym: arteria collateralis media. (05 Mar 2000) |
| arteria genus media | <anatomy, artery> Origin, popliteal; distribution, synovial membrane and cruciate ligaments of knee joint. Synonym: arteria genus media, arteria articularis azygos. (05 Mar 2000) |
| arteria meningea media | Origin, maxillary; branches, petrosal, superior tympanic, frontal and parietal; distribution, to parts mentioned and through terminal branches to anterior and middle cranial fossae; anastomoses, meningeal branches of occipital, ascending pharyngeal, ophthalmic and lacrimal, stylomastoid, accessory meningeal branch of maxillary, and deep temporal. Synonym: arteria meningea media. (05 Mar 2000) |
| arteria rectalis media | <anatomy, artery> Origin, internal iliac; distribution, middle portion of rectum; anastomoses, inferior rectal and superior rectal. Because the latter is a tributary of the portal system, this is a portosystemic or portocaval anastomosis. Synonym: arteria rectalis media, middle haemorrhoidal artery. (05 Mar 2000) |