NCLE Latest Update (2022/2023) Already Graded A+

NCLE Latest Update (2022/2023) Already Graded A+ annular bifocal contact A lens with distance portion ground into the center of the lens and the near portion ground into the periphery aphakic lenses lenses designed for post-cataract fitting apical zone of cornea the central portion of the cornea with a constant radius of curvature. Also called the corneal cap. artificial tears medications, many of them over the counter, to treat dry eyes aspheric lens A non-spherical lens, in which the radii of curvature increase towards the periphery rather than remaining equal at all points. Aspheric lenses reduce optical aberration and improve resolution. bactericide a chemical that disinfects and kills pathogenic organisms. benzalkonium chloride a preservative used in contact lens solutions because of its germicidal qualities biomicroscopy Ophthalmic examination of the eye by use of a slit lamp and a magnifying lens; also known as a slit-lamp exam. 10 to 50 times magnification bullous keratopathy corneal edema with painful blisters in the epithelium due to corneal endothelial dysfunction. treated frequently with a therapeutic soft lens. Burton lamp an ultraviolet light used to illuminate the fluorescein dye that is used to analyze the fit of a rigid contact lens. chord length the straight-line measurement of the contact. lens diameter from edge to edge. circumcorneal injection Redness around the limbus surrounding the cornea contact lens wetting angle the angle between the liquid and the lens surface. contour lens a tricurve lens designed to conform to the curvature of the cornea, which flattens as it extends in the periphery. copolymer two or more chemicals that are combined to form a new chemical compound. corneal cap Apical zone or central zone of the cornea that has a constant area of curvature. corneal diameter the diameter of the cornea, usually taken along the horizontal meridian with a ruler. Also called visible iris diameter. corneal edema swelling of the cornea caused by hypoxia or insufficient oxygen deturgence, corneal the state of relative dehydration maintain by the normal intact cornea that enables it to remain transparent diagnostic fitting set a set of trial lenses used to gain an overview of the fit of a contact lens. disinfection physical or chemical procedures that kill common pathogenic organisms but may permit some nonpathogenic organisms to survive. DK value a measure of the oxygen permeability through a given material where D is the diffusion coefficient for oxygen movement in the lens material and K is the solubility of oxygen in this material. double slab-off lenses sometimes called thick-thin lenses; the upper and lower portions of the lens are reduced in thickness so that when the lens is placed on the eye these portions lie under the upper and lower eyelids. The thin zones aid in stabilizing toric soft lenses. dry spots areas of drying as noted by absent areas of fluorescein-stained tear film on the cornea when the patient stares. Dyer nomogram system of lens ordering a simplified system of ordering rigid lenses based on clinical experience, corneal topogometry and charts of associated lens parameters. endophthalmitis an inflammation of the entire eye including the outer coats. enzyme cleaner a cleaning agent that acts on a soft lens by a digestion of protein. epithelial edema edema of the superficial layer of the cornea. Esthesiometer (Cochet-Bonnet) a device used to evaluate corneal sensitivity, consisting essentially of a nylon thread mounted in a handle so that its length may be varied and calibrated in milligrams of weight necessary to bend a given length of the thread when pressed against the cornea. eversion of the eyelid the folding back of the eyelid on itself. finished lens a complete lens with anterior and posterior curves, a specified diameter, a designated peripheral curve, and edge design. fitting set a complete inventory of lenses of graduated powers and base curves. flare flutterings or fringing of lights caused by a lens with an optic zone too small as a decentered lens or an excessively loose lens.