NCLE exam prep (with complete answers)

optic zone correct answers the central portion of a contact lens which contains the refractive power and generally corresponds to the central corneal cap posterior apecal radius correct answers this term is generally used in reference to spin-cast soft lenses. the curvature of the posterior surface of the lens changes with the refractive power. the radius of curvature is measured at the apex of the posterior surface. steeper base curve correct answers occurs when the posterior radius of curvature is decreased (i.e. 8.4 to 8.1 mm) flatter base curve correct answers occurs when the posterior radius of curvature is increased (i.e.8.1 to 8.4 mm) bicurve lens correct answers a contact lens which contains two curves: one base curve and one secondary curve. it is usually small 7.5 to 8.8 mm on diameter, relatively steep and made with narrow peripheral curves about 0.2 mm. lenses are usually intrapalpebral lenses, designed to fit within the palpebral fissure limits. tricurve lens correct answers a contact lens which contains three curves: a base curve, an outer peripheral posterior curve (PPC), and an intermediate posterior curve (IPC). lenses are generally larger, 9.5 mm or greater. multicurve lens correct answers contains a base curve and three or more peripheral curves. usually a larger lens. junctional zone correct answers the junction of two curves blending correct answers the smoothing of a junctional zone by removing the sharp line between the zones lens diameter or chord diameter correct answers the width of a lens or the measurement from one edge of the lens to the opposite edge curve widths correct answers the width of the CPC, PPC, or IPC central thickness correct answers separation between the anterior and posterior surface at the geometric center of the lens. minus lenses are thinner, plus lenses are thicker ballasted lens correct answers lens with a heavier base which becomes oriented inferiorly or downward when the lens is worn prism ballated lens correct answers a ballasted lens which utilizes a prism wedge designed to weight the lens