L.3 - Basic CL Design Flashcards
(31 cards)
What is Back Surface Power?
Effective power of a lens when measured from the back surface.
Define Back Surface Toric Lens.
A lens in which the posterior surface has two different radii of curvature, and the anterior surface is spherical.
What characterizes a Ballasted Lens?
Lens with a heavier base which becomes oriented inferiorly, or downward, when the lens is worn.
What is a Bicurve Lens?
A contact lens that contains two curves: one base curve and one secondary curve.
What is the typical diameter range for a Bicurve Lens?
Usually small (7.5 to 8.8 mm in diameter).
What defines a Bitoric Lens?
A lens in which both the posterior and anterior surfaces contain two different radii of curvature.
What does Blending refer to in lens design?
The smoothing of the junction that results from changes in back surface curves.
What is Central Thickness in relation to a lens?
Separation between the anterior and posterior surface at the geometric center of the lens.
What does CPC stand for?
Central Posterior Curve (Base Curve (BC)).
What are Curve Widths?
The width of the CPC, PPC, or IPC.
What is an IPC?
Intermediate Posterior Curve.
What is a Flatter Base Curve?
Occurs when the posterior radius of curvature is increased.
Define Front Surface Toric Lens.
A lens in which the anterior surface has two different radii of curvature, and the posterior surface is spherical.
What is a Junctional Zone (JZ)?
The junction of two curves.
What is a Lathe Cut Soft Lens?
A method of manufacturing soft contact lenses using a machine lathe.
What does Lens Diameter refer to?
The width of a lens, or the measurement from one edge of the lens to the opposite edge.
What is a Lenticular Bowl?
A lens design used in high plus powers consisting of a central optic zone and a surrounding non-optic, peripheral carrier.
What is a Multicurve Lens?
Contains a base curve and three or more peripheral curves.
What is the Optic Zone (OZ)?
The central portion of a contact lens that contains the refractive power.
What does the term Posterior Apical Radius refer to?
The curvature of the posterior surface of the lens changes with the refractive power.
What does PPC stand for?
Peripheral Posterior Curve.
What are Principal Meridians in lens design?
The power meridians which correspond to the shortest and longest radii of curvature.
What is a Prism Ballasted Lens?
A ballasted lens that utilizes a prism wedge to maintain a specific orientation.
Define Spherical Equivalent.
A spectacle or contact lens prescription expressed only as a sphere.
