Ординатура / Офтальмология / Английские материалы / Quick Reference Dictionary of Eyecare Terminology 4th edition_Ledford, Hoffman_2005

214 truncation/typoscope

truncation: Method of stabilizing toric contact lenses by flattening one edge of the lens (usually the inferior) so that it is no longer round, thereby creating a linear edge that rests against the lid margin; truncation is employed to help prevent rotation and maintain the orientation of toric contact lenses in the proper axis; compare dynamic stabilization, posterior toric, and prism ballast.

Tscherning aberrometry: Aberrometry method in which a pattern of light spots is shone into the eye and photographed; distortions in the pattern indicate any optical aberrations that may be present in the eye.

tumbling "E": Another term for "E" test.

tunnel field: Nonphysiologic visual field loss in which the patient’s “tunnel vision” does not expand with increased distance, as does true tunnel vision; usually associated with hysteria or malingering.

tunnel vision: True visual field defect in which only a small central portion of the visual field remains functional.

20/20: Considered to be “normal” vision, the numerator stands for the standard 20-foot test distance used in measuring distant visual acuity; the denominator represents the smallest line of test objects accurately identified by the patient from 20 feet away; 20/40 would mean that the patient could identify figures from 20 feet that the “normal” person could identify from 40 feet away (thus, the larger the denominator, the poorer the vision).

typoscope: Low-vision aid consisting of a rectangle of dark, nonreflective material with a narrow horizontal slit through which type can be read, thereby minimizing glare from the page and isolating the words being read.

U

UGH syndrome: Abbreviation for combination of uveitis, glaucoma, and hyphema; inflammatory condition of internal ocular structures occurring as a complication of intraocular lens implantation.

ultrasonography: Imaging internal structures via the use of ultrasound techniques; also called echography.

ultrasound: Imaging technique that uses sound waves to produce an image; in ophthalmology, used to measure the axial length of the eye as well as to visualize the eye’s inner structures; see A-scan and B-scan.

ultraviolet (UV): Portion of the electromagnetic spectrum with short wavelengths, not visible to the human eye; ultraviolet radiation causes sunburn and tanning and has been implicated in certain ocular conditions, notably corneal burns and cataract formation.

ultraviolet A (UVA) and B (UVB): The two bands of ultraviolet radiation.

ultraviolet blocker: Substance incorporated into spectacle, contact, and intraocular lenses to shield the eye from the ultraviolet component of sunlight.

uncorrected visual acuity (UCVA, VAsc): Visual acuity measured without corrective lenses in place; compare corrected visual acuity; see also best corrected visual acuity.

uncrossed diplopia: Another term for homonymous diplopia.

undercorrection: State in which the power of corrective lenses or the effect of refractive surgery is insufficient to achieve the best visual acuity; compare overcorrection.

216 unilateral/uveitis

unilateral: General anatomic term describing a structure or process appearing or occurring on only one side; in ophthalmic usage, referring to a single eye; also called monocular or uniocular; compare bilateral.

uniocular: Another term for unilateral, as in one eye. universal precautions: Specific rules and recommenda-

tions intended to prevent exposure to disease and/or injury (eg, hand washing, protective wear, handling of contaminated waste, etc).

uvea: The tissues of the eye that are heavily pigmented and consist primarily of blood vessels: the choroid, ciliary body, and iris (considered as a whole system). uveitis: Inflammation of all or part of the uvea; anterior u. uveitis involving only the iris (see iritis) and/or ciliary body (see iridocyclitis); ); intermediate/peripheral u. inflammation of the ciliary body; also called cyclitis, pars planitis; phacolytic u. uveitis resulting from degeneration and leakage of lens tissue; posterior u. uveitis involving the choroid (choroiditis), retina (retinitis), retinal blood vessels (retinal vasculitis), and/or optic nerve (papillitis, optic neuritis); often referred to simply as uveitis, creating confusion as to

what is meant.

V

V pattern: See esotropia and exotropia.

Van Lint block: Injection of anesthetic agents to achieve akinesia (ie, prevention of movement) of the eyelids. vasovagal reflex or response: Fainting or near fainting associated with the vagus nerve; in eyecare, this can occur on instillation of eye drops or contact lenses, or

during tonometry.

vault: Another term for apical clearance (definition 1). vergence: 1. In optics, the gathering together or spread-

ing apart of parallel light rays, either naturally or as a result of passing through a lens; see also convergence and divergence; 2. in ophthalmic usage, motion of the eyes toward or away from one another; also called disjunctive movements; see also convergence and divergence; compare duction.

vericella-zoster virus (VZV): The herpes virus that causes shingles (zoster) and chickenpox (vericella).

verification: Measuring the parameters of a contact lens, spectacle lens, or pair of spectacles to be sure that the items match what was ordered prior to dispensing to the patient.

vernal conjunctivitis: See conjunctivitis.

verruca vulgaris: An epidermal wart caused by a virus. version: Coordinated movement of both eyes in the same

direction; also called conjugate movement.

vertex distance: Distance along the line of sight from the cornea to the back surface of a spectacle lens.

218 vertex power/vision therapy

vertex power: Focusing power of a spectacle lens measured from either of its surfaces; back v.p. portion of the total refractive power imparted by the posterior surface of a lens; front v.p. portion of the total refractive power imparted by the anterior surface of a lens.

vertigo: A false sense of spinning or turning. videokeratography: Another term for corneal topography. virus: An intracellular parasite that transfers its own

genetic material into the living cells of the host and causes infection (eg, Herpes, adenovirus).

viscodissection: Surgical technique in which a viscoelastic substance is injected between tissues (commonly the tissues surrounding the lens nucleus) in order to separate them and facilitate subsequent manipulation; compare hydrodissection.

viscoelastic: Any one of a number of thick gels manufactured for use in ophthalmic surgery, injected into the eye to help maintain the shape of ocular structures and as a lubricant/coating to minimize trauma from surgical instruments and implants; currently used viscoelastic materials include chondroitin sulfate, hyaluronic acid, and methylcellulose (used individually or in combination and marketed under several brand names, see Appendix 11).

vision: Action of the eyes, nervous system, and brain in capturing reflected light from the environment and converting it to perceived images; see also binocular v., distance v., low v., near v., etc.

vision therapy or training (VT): Any of several systems employing ocular exercises and/or lenses to enhance development or to correct deficiencies of stereopsis, hand-eye coordination, vision, etc; see also orthoptics.

visual acuity (VA): Level of visual clarity; specifically, the ability to distinguish fine details, often expressed as a score on Snellen's, Jaeger’s, or other vision test charts; best corrected v.a. (BCVA) highest level of visual acuity that can be attained with corrective lenses in place; corrected v.a. (VAcc) visual acuity measured with current corrective lenses in place; distant v.a. acuity for far-off tasks, especially 20 feet or more; near v.a. acuity at close range, especially for reading; uncorrected v.a. (UCVA or VAsc) visual acuity measured without corrective lenses in place; see also count finger v., hand-motion v., light perception, light projection, and no light perception.

visual acuity test: Method of measuring visual acuity; the test used depends upon the patient (ie, literate, responsive, etc); see also specific test (ie, Allen cards, "E" test, Snellen chart, etc).

visual axis: Imaginary line traced from the fovea to the object of fixation, also called the line of sight.

visual cortex: That part of the brain responsible for vision, primarily an area in the occipital lobe known as Brodmann area 17; also called the striate cortex.

visual efficiency: A rating based on the loss of central visual acuity and peripheral vision in the better eye of a person who is not legally blind.

visual evoked cortical potential (VECP): Another term for visual evoked response.

visual evoked potential (VEP): Another term for visual evoked response.

visual evoked response (VER): Fluctuation of brain activity in the visual cortex resulting from a visual stimulus, measurable on electroencephalography; also called visual evoked cortical potential and visual evoked potential; flash VER indicates the basic soundness of the visual system using a flashing light; pattern VER provides information about visual acuity using an alternating checkerboard pattern.

220 visual field/visual purple

visual field (VF): 1. Area around the fixation point of each eye, generally circular in shape, in which objects are perceived; also called field of vision; 2. in clinical usage, graphs representing the result of perimetry and other such tests are often simply referred to as visual fields; visual field testing is often conducted to delineate and measure areas of the retina that are damaged (eg, by glaucoma or retinal disorders), as well as to determine any portions of the optic nerve tract that might be compromised; also called field; see also perimetry.

visual field defect: Area of diminished or absent vision within the visual field; see also hemianopia, quadrantanopia, scotoma, and tunnel field; hysterical v.f.d. apparent area of diminished or absent vision within the visual field that cannot be correlated to ocular damage or disease and, thus, seems to have an emotional basis; the isopters have a “spiral” pattern or a tube pattern that does not expand with distance from the subject.

visual pathway: The route of nerve fibers involved in vision; order is as follows: retina (rods, cones, nerve fiber layer), optic nerve, optic tract, optic radiations, occipital cortex.

visual purple: Another term for rhodopsin.

vitrectomy: Surgical procedure involving partial or total removal of vitreous humor and any membranes, blood, or other tissue in the posterior segment; anterior v. vitrectomy used to remove vitreous in the anterior segment (generally present as a complication of other ocular surgery); automated v. vitrectomy performed using a cutting probe with irrigation and aspiration capabilities; complete v. removal of all vitreous from the posterior chamber; also called total v.; manual v. vitrectomy performed using scissors rather than a vitrector; also called scissors v.; open-sky v. vitrectomy performed by opening the cornea and removing the lens; pars plana v. vitrectomy performed by making small incisions and inserting instruments through the pars plana; partial v. removal of only part of the vitreous humor from the posterior chamber; scissors v. another term for manual v.; total v. another term for complete v.

vitrector: Surgical instrument designed for performing vitrectomy, incorporating a cutting probe with irrigation and aspiration capabilities.

vitreous, vitreous body or humor: Clear, fibrous, gel-like material filling the posterior segment of the eye, located behind the lens capsule and comprising about twothirds of the total volume of the eye; typically referred to simply as the vitreous.

vitreous detachment: Another term for posterior vitreous detachment (PVD).

vitreous face: The anterior hyaloid membrane. vitreous floaters: Another term for floaters.

vitreous membrane: Another term for hyaloid membrane. vitreous strands: Vitreous humor in the anterior chamber as strands of viscous, transparent tissue still

attached to the hyaloid membrane.

222 vitreous tap/vortex veins

vitreous tap: Diagnostic procedure in which a small amount of vitreous humor is removed for testing, usually to perform a culture to confirm the existence and cause of infection.

von Graefe’s sign: Delay in or absence of downward motion of upper eyelid when the eye looks downward, associated with Graves’ disease (which involves serious dysfunction of the thyroid gland); compare pseudo-von Graefe’s sign.

vortex veins: Veins formed by the joining of veins draining blood from the iris, ciliary body, and choroid exiting the eye through the sclera just posterior to the equator of the globe.

W

wall-eye: Common term for exotropia.

wavefront: 1. In optics, a theoretical surface composed of all points that are the same distance from an object emitting or reflecting light; 2. in refractive surgery, usually referring to the “flat” image of a distant object that may be distorted by the optical aberrations of the eye.

wavefront analysis: Another term for aberrometry. wavefront analyzer: Another term for aberrometer. wavefront-guided ablation: In refractive surgery, a pro-

cedure in which the optical properties of a patient's eye are measured by aberrometry, which is then used to create an excimer laser ablation pattern specifically designed to correct the myopia, hyperopia, astigmatism, or higher-order aberrations of that eye.

wet macular degeneration: See macular degeneration. wetting angle: Angle between the surface of a drop of

water and the surface of the material on which the drop lies; in ophthalmic usage, usually a description of contact lens materials, referring to the spread of moisture on the lens surface; the smaller the wetting angle, the more hydrophilic or “wettable” the material; also called contact angle.

white blood cell (WBC): Blood cell type that fights disease; also called leukocyte; types of WBC's include basophile, eosinophile, and neutrophile (see entries for each of these).

white-to-white measurement: Diameter of the cornea as measured from the edges of white scleral tissue.

with-the-rule (WTR) astigmatism: See astigmatism.