Glossary of Optical Terms Compiled by Davis Vision
Total Page:16
File Type:pdf, Size:1020Kb
Glossary of Optical Terms Compiled by Davis Vision GLOSSARY OF OPTICAL TERMS A-Lenses Colored or neutral lenses used to reduce dangerous visible and invisible radiation, or to reduce glare. A-Dimension A measurement of the Boxing System that measures the distance between horizontal tangents to the bevel of a lens. Abduction Divergence - The outward rotation of a pair of eyes in the attempt to maintain single binocular vision when stimulated by a base in prism or base in prisms. Aberration An imperfection in a lens or optical system that prevents a point focus. Ablepsia (A blep se ah) Blindness Abrasion In contact lenses, scraping of the cornea due to ill-fitting lenses or over wearing of lenses. Absorption The interception of radiant energy as it passes through a medium in which the energy is converted into heat, chemical energy or photoelectric energy. For example, ultraviolet light is converted into fluorescence or phosphorescence. Most optical, media have selective absorption, that is, absorb certain radiation (colors) differently. Absorptive lenses Eyeglass lenses that absorb bright lights. Their purpose is to provide eye comfort against glare. Access The brand name for Sola enhanced, near vision lenses. An access lens is a single vision reading lens with an enhanced range (extra close) at the bottom of the lens. Accommodation The act of increasing the dioptric power of the eye by an increase in the power of the crystalline lens to permit objects at different distances to be clearly seen. Accommodative Amplitude The total amount of dioptric power which the eye or eyes are increased by maximum effort of the ciliary muscle. The dioptric power increase of the near point over the dioptric power of the far point. Page 1 Glossary of Optical Terms Compiled by Davis Vision Acrylic (ak krill lex) An economical lens material most commonly formed by the injection molding process. Lightweight and optically correct Acuity Clearness, distinctness, sharpness of vision. Addition (Add) Dioptric power added to distance prescription to supplement accommodation for some finite distance; such as reading. The dioptric power of a bifocal segment. After-image phenomenon Ability of the eye to retain sight of an image during eye blinks. Against motion Objects sighted through convex (plus) lenses move in an opposite (against) direction as the convex lenses are moved from side to side. See also with motion. Age-related macular degeneration (AMD) An acquired retinal disorder characterized by degeneration in the central (macular) area of the retina. This is the leading cause of blindness in persons over age 65. A-Scan Ultrasonography A noninvasive diagnostic test in which sound waves are used to determine the position of, and distances between, structures within the eye and orbit. Amaurosis Blindness Amblyopia (Am ble o pe ah) Low or reduced visual acuity not correctable. Amblyopia is said to exist if vision is uncorrectable to 20/30 or if vision in one eye is significantly less than that of the other. Ametropia The refractive state of a static eye in which the secondary focus does not fall upon the retina. Aniseikonia (An ih si ko neah) A relative difference in size and/or shape of the ocular images (right eye does not see an object the same size as the left eye). Aniseikonic Lens A lens designed to correct the image size difference. Anisocoria (An I so ko reah) Pupils of unequal size. Page 2 Glossary of Optical Terms Compiled by Davis Vision Anisometropia (An I so me tro peah) A condition of unequal vision for two eyes. Anomalies (A nom ah les) A deviation from the usual or norm. ANSI American National Standards Institute- The organization which is responsible for setting all of the limitation, tolerances, and testing procedures that must be adhered to in many industries, including ophthalmic fabrication. Anterior Close to the front. Antimetropia One eye nearsighted; the other far- sighted. AOA (American Optometric Association) The national, professional association representing optometry Aphakia (A fa ke ah) Crystalline (clear lens behind eye) lens absent. Condition following cataract surgery. A .R. Coat Anti-reflection lens coating. A clear coating that limits light reflection by allowing the maximum amount of light to pass through the lens. (E.g. Reflection-Free™) Asthenopia A group of symptoms generally referred to as “eyestrain”. Included are: headaches, tearing, ”tired eyes,” itching, burning, and blurred vision. Astigmatism (A stig mah tism) The eye is shaped like a football instead of a basketball, causes light rays to be distorted. Associates Term used by Davis Vision, rather than employee, to refer to its work force. Associate refers to people working together towards a common goal. Automated Field Measurement An examination to determine the viability of the nerve fiber layer of the retina and its effect on the field of vision of an individual. Axis Degree at which eye power manifests it self. Page 3 Glossary of Optical Terms Compiled by Davis Vision Axis, Cylinder That principal meridian which contains only the spherical power component of a sphero-cylinder lens. Axis, Optical The straight line perpendicular to both faces of a lens along whose path a ray will pass without being deflected. It will intersect a spherical lens of a minus power at its thinnest point and a spherical lens of plus power at its thickest point. If the lens has prism power, the optical axis may lie outside the lens. B-Dimension A measurement of the Boxing System which measures the distance between horizontal tangents to the bevel of a lens. Back Order An order placed to fill a definite order from a dispenser. Also called short order, or special order. Base The finished side of a semi-finished blank. The term refers to the curvature of the finished side. See Curve, Base. Base- Apex line The line at a right angle to the refracting edge of a prim. The line on which an object appears to be displaced by refraction. Base Curve The meridian of least curvature on a cylindrical surface. It may be found on either the convex or concave side of a meniscus lens. Benchmarking An improvement process in which an organization measures its performance against that of best-in-class organizations, determines how those organization’s achieved their performance levels, and uses the information to improve its own performance. The subjects that can be benchmarked include strategies, operation, processes, and procedures. The objective of benchmarking is to identify and learn “best practices” and then to use those procedures to improve performance. Bevel Apex The point of the bevel of a lens. Bifocal (Bi fo kal) A lens containing two different powers one for distance, and one for near. Bilateral (Bi lat er al) Both sides or both halves. Bin Card A piece of paper or cardstock on which the inventory, sales and ordering of frames is recorded in the laboratory. Binocular (Bin ok u lar) Use of both eyes simultaneously Page 4 Glossary of Optical Terms Compiled by Davis Vision Biomicroscopy High magnification examination of the anterior segment of eye. Blank, Molded A blank that is unfinished on both sides when it arrives from the factory. It is used to grind lenses for non-standard prescriptions or prescriptions that are particularly strong. Blended Bifocal Lens containing two different posers, one for distance, and one for near. Segment with near prescription is invisible. Blended Myodisc A lenticular lens used in the correction of high myopia, having a concave central corrective area 20 to 30mm in diameter, with a flat, non-corrective periphery. Blepharitis (Blef ah ri tis) Inflammation of eyelid. Blind Spot The area on the retina where the optic nerve enters. It is not sensitive to light since it has no visual receptors. Blur point Where an object appears blurred either by moving it closer to the eye or by adding certain lenses or prisms until the test target blurs. Boxing System A system of measurement used to define various prescription requirements relative to lens and frame dimensions. Bridge The supportive structural member connecting the two eyes of an ophthalmic frame font. Bridge, Keyhole A bridge design for a front that does not permit continuous contact between the nose and the front in the area of the nasal crest. Bridge, Saddle A bridge design for a front that permits continuous contact between the nose and the front in the area of the nasal crest. Bridge, Size The shortest horizontal distance between lenses (DBL), measured in millimeters. BVI (Better Vision Institute) An organization dedicated to the preservation of sight through community education and public awareness. Page 5 Glossary of Optical Terms Compiled by Davis Vision Canthus The point at which the upper and lower lids of the eye meet to form an angle. Inner c. junction point nearer to the nose. Outer c. junction point nearer to the temples Carrier Number Used to uniquely identify the billing party of a Plan. The billing party may have multiple Plans and therefore multiple Client Control Numbers, e.g., Blue Cross might have a Carrier Number of 101 & 3 Plans: Plan A with a Client Control Number of 90 Plan B with a Client Control Number of 91 Plan C with a Client Control Number of 92, so A C# of 101 and CC#’s of 90, 91, and 92 are all related to Blue Cross Case Harden Heat treatment of a glass lens for impact resistance. Cataract (Kat ah rakt) Partial or complete loss of transparency of the crystalline lens. Clouded lens is removed by surgery and usually replaced with plastic lens called Intraocular lens implant. Cellulose Acetate A thermoplastic which is not easily flammable. It is used as the material for spectacle frames.