NCLE Practice Questions and Answers Already Passed

base curve -Answerrefers to the radius of curvature of the central posterior surface of the lens. It may be expressed in diopters of surface power (D) or in millimeters (mm) of radius or curvature. optical zone -Answerthe chord diameter over which the base curve extends on the posterior surface of the contact lens, described in millimeters secondary or intermediate curves -Answerlies between the base curve and the peripheral curve on the posterior lens surface, usually 0.70mm to 1.50mm flatter than the base curve radius, this allows the lens to better align the flatter portion of the cornea adjacent to the optical zone peripheral curve -Answerthe outermost curve on the posterior lens surface, its function is to clear the flatter periphery of the cornea and to prevent lens impingement in the limbal areas as the lens moves with blinking