NCLE Study Questions with Correct Answers

NCLE Study Questions with Correct Answers annular bifocal contact - Answer-A lens with distance portion ground into the center of the lens and the near portion ground into the periphery aphakic lenses - Answer-lenses designed for post-cataract fitting apical zone of cornea - Answer-the central portion of the cornea with a constant radius of curvature. Also called the corneal cap. artificial tears - Answer-medications, many of them over the counter, to treat dry eyes aspheric lens - Answer-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 - Answer-a chemical that disinfects and kills pathogenic organisms. benzalkonium chloride - Answer-a preservative used in contact lens solutions because of its germicidal qualities biomicroscopy - Answer-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 - Answer-corneal edema with painful blisters in the epithelium due to corneal endothelial dysfunction. treated frequently with a therapeutic soft lens. Burton lamp - Answer-an ultraviolet light used to illuminate the fluorescein dye that is used to analyze the fit of a rigid contact lens. chord length - Answer-the straight-line measurement of the contact. lens diameter from edge to edge. circumcorneal injection - Answer-Redness around the limbus surrounding the cornea contact lens wetting angle - Answer-the angle between the liquid and the lens surface. contour lens - Answer-a tricurve lens designed to conform to the curvature of the cornea, which flattens as it extends in the periphery. copolymer - Answer-two or more chemicals that are combined to form a new chemical compound. corneal cap - Answer-Apical zone or central zone of the cornea that has a constant area of curvature. corneal diameter - Answer-the diameter of the cornea, usually taken along the horizontal meridian with a ruler. Also called visible iris diameter. corneal edema - Answer-swelling of the cornea caused by hypoxia or insufficient oxygen deturgence, corneal - Answer-the state of relative dehydration maintain by the normal intact cornea that enables it to remain transparent diagnostic fitting set - Answer-a set of trial lenses used to gain an overview of the fit of a contact lens. disinfection - Answer-physical or chemical procedures that kill common pathogenic organisms but may permit some nonpathogenic organisms to survive. DK value - Answer-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.