NCLE Prep Exam 3 of 4 Questions and Answers 2023

The tolerance for the overall lens diameter according to the ANSI standards is: A. +/-0.005mm B. +/-0.05mm C. +/-0.01mm D. +/-0.1mm - B. According to the ANSI standards (Z80.2-1989), the tolerance for the overall diameter of a contat lens is +/-0.05mm. ANSI standards have been developed to maintain quality in the contact lens industry. It is important to have an understanding of the ANSI guidelines. All of the following will enable the practitioner to verify the overall rigid gas permeable lens diameter except: A. Slot gauge B. Shadowgraph C. Measuring magnifer D. Radiuscope - D. Radiuscope The slot gauge, shadowgraph and measuring magnifier will all enable the practitioner to verify the overall lens diameter of rigid gas permeable lens. The radiuscope is an instrument that will measure the base curve of a rigid lens. Placing the concave side of a rigid gas permeable lens against the lens stop of the lensometer, will provide you with which of the following? A. Back vertex power B. Front vertex power C. Best vertex power D. Closest vertex power - A. Back vertex power By placing the back (posterior) surface of the rigid gas permeable lens against the lens stop, the reading that results will be in back vertex power An instrument that allows simultaneous verification of lens diameter, optic zone width and peripheral curve width is: A. Measuring magnifier B. Ophthalmometer C. Profile analyzer D. Radiuscope - A. Measuring magnifier