| OA | obstructive apnea; occipital artery; occipito-anterior; occiput anterior; octanoic acid; ocular albi... |
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| OASD | ocular albinism-sensorineural deafness [syndrome] |
| OCP | octacalcium phosphate; ocular cicatricial pemphigoid; oral case presentation; oral contraceptive pil... |
| OHS | obesity hypoventilation syndrome; occipital Horn syndrome; occupational health service; ocular histo... |
| OHT | ocular hypertension |
| unit of ocular convergence | The amount of convergence required to view binocularly an object 1 meter distant and exerting 1 diopter of accommodation. Synonym: unit of ocular convergence. (05 Mar 2000) |
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| filar micrometre ocular | <microscopy> A micrometre ocular with crossed lines which can be simultaneously focused in and moved across the field by means of a micrometre screw. The amount of displacement can be read in 0.01 steps on the micrometre drum head. This makes a very delicate measuring device, since calibration of the micrometre scale by means of a stage micrometre gives values for each interval on the drum head which are much less than the resolving power of the highest-aperture objectives. (05 Aug 1998) |
| fixational ocular movement | Rotation of the eyes during voluntary fixation on an object; tremors, flicks, and drifts occur. (05 Mar 2000) |
| fixation, ocular | The direction of the gaze so that the visual image of the object falls on the fovea centralis of the retina, the area of the most acute vision. (12 Dec 1998) |
| Frenkel's anterior ocular traumatic syndrome | <syndrome> An obsolete term for traumatic iridoplegia, which consists of mydriasis, hyphema, small iris tears near the pupil, discrete punctate opacities of the lens, and occasionally iridodialysis. (05 Mar 2000) |
| acromial angle | The prominent angle at the junction of the posterior and lateral borders of the acromion. Synonym: angulus acromialis. (05 Mar 2000) |
| acute angle | Any angle less than 90 |
| acute angle closure glaucoma | <ophthalmology> An increase in pressure within the anterior chamber of the eye. There are two forms of glaucoma: acute angle closure and open angle glaucoma. (27 Sep 1997) |
| adjacent angle | An angle with a line in common with another angle. (05 Mar 2000) |
| alpha angle | The angle between the visual and optic axes as they cross at the nodal point of the eye, the angle between the visual line and the major axis of the corneal ellipse. (05 Mar 2000) |
| alveolar angle | The angle between the horizontal plane and a line connecting the base of the nasal spine and the middle point of the projection of the alveolus of the maxilla. (05 Mar 2000) |
| angle | 1. To fish with an angle (fishhook), or with hook and line. 2. <geometry> The figure made by two lines which meet. The difference of direction of two lines. In the lines meet, the point of meeting is the vertex of the angle. 3. A projecting or sharp corner; an angular fragment. "Though but an angle reached him of the stone." (Dryden) Curvilineal angle, one formed by two curved lines. External angles, angles formed by the sides of any right-lined figure, when the sides are produced or lengthened. Internal angles, those which are within any right-lined figure. Mixtilineal angle, one formed by a right line with a curved line. Oblique angle, one acute or obtuse, in opposition to a right angle. Obtuse angle, one greater than a right angle, or more than 90 deg . Rectilineal or Right-lined angle, one formed by two right lines. Right angle, one formed by a right line falling on another perpendicularly, or an angle of 90 deg (measured by a quarter circle). Solid angle, the figure formed by the meeting of three or more plane angles at one point. Spherical angle, one made by the meeting of two arcs of great circles, which mutually cut one another on the surface of a globe or sphere. Visual angle, the angle formed by two rays of light, or two straight lines drawn from the extreme points of an object to the center of the eye. 4. <astronomy> A name given to four of the twelve astrological houses. Origin: F. Angle, L. Angulus angle, corner; akin to uncus hook, Gr. Bent, crooked, angular, a bend or hollow, AS. Angel hook, fish-hook, G. Angel, and F. Anchor. (16 Mar 1998) |
| angle closure glaucoma | <ophthalmology> Primary glaucoma in which contact of the iris with the peripheral cornea excludes aqueous humor from the trabecular drainage meshwork causing a sudden blockage of the normal fluid circulation within the eyeball resulting in increased intraocular pressure. Increased pressure within the eyeball can cause damage to the optic nerve and blindness. Symptoms include severe eye or facial pain, nausea, vomiting, decreased vision, blurred vision and seeing halos around objects. The eye appears red with a steamy cornea and a fixed (nonreactive) dilated pupil. Treatment is emergent with medications to lower the pressure within the eye. Synonym: acute glaucoma, closed-angle glaucoma, narrow-angle glaucoma. (14 Aug 2000) |
| Angle, Edward | <person> U.S. Orthodontist, 1855-1930. See: Angle's classification of malocclusion. (05 Mar 2000) |
| angle of anomaly | <ophthalmology> An obsolete term for the degree of deviation from parallelism of the visual axes of the eyes. (05 Mar 2000) |