NCLE Exam Prep Questions and Answers Latest Update

optic zone -Answerthe central portion of a contact lens which contains the refractive power and generally corresponds to the central corneal cap posterior apecal radius -Answerthis 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 -Answeroccurs when the posterior radius of curvature is decreased (i.e. 8.4 to 8.1 mm) flatter base curve -Answeroccurs when the posterior radius of curvature is increased (i.e.8.1 to 8.4 mm) bicurve lens -Answera 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.