ABO-NCLE practical Exam questions with correct answers Single Vision CORRECT ANSWER corrects for one distance Multifocal CORRECT ANSWER Corrects with two or more prescriptions (or 'powers') Bifocal CORRECT ANSWER lens having two focus strengths Trifocal CORRECT ANSWER pertaining to having three focus strengths Calculating Prismatic Effects CORRECT ANSWER obtained at the center of an optical lens by producing a difference in edge thickness, either by grinding the back surface at an angle to the front surface during lens surfacing or, if the lens has sufficient power, de-centering the optical center of the lens Compounding Prism CORRECT ANSWER BI & BI BO & BO BU & BD Cancelling Prism CORRECT ANSWER BI & BO BD & BD BU & BU Prentice's Rule CORRECT ANSWER P=hcm x D P=amount of prism created h= number of cm OC moved cm= centimeters (convert to mm, divide by 10) D= power in meridian with error 1 / 2
Vertical Imbalance CORRECT ANSWER The difference in vertical prism power at the reading level in a pair of lenses.OC Height's by lens CORRECT ANSWER SV = 1/2 of B Progressive = Fitting cross FT = 5mm above segment Vertex Compensation CORRECT ANSWER A plus lens when moved farther from the eye gains in plus power Distance is 0 with CL because they are on the eye Vertex compensation Formula CORRECT ANSWER De= Dl/(1 + d xDl) De= diopter effective value of error created D/= lens power (given power) d= amount in METERS lens moved from refracted position to position lens is worn Keep sign for what it is (+/-)
- to d means moves away
- / 2
Horizontal Centration CORRECT ANSWER PD Vertical Centration CORRECT ANSWER OC Horizontal & Vertical Centration Formula CORRECT ANSWER Given PD/OC - Human PD/OC= mm moved Frame PD is found by adding A+DBL Power in Oblique Meridians CORRECT ANSWER Dt= (sina)²x Dc +Ds Dt= Total Power we need