ABO Practical Exam 2023

Single Vision - ANSWER-corrects for one distance Multifocal - ANSWER-Corrects with two or more prescriptions (or 'powers') Bifocal - ANSWER-lens having two focus strengths Trifocal - ANSWER-pertaining to having three focus strengths Calculating Prismatic Effects - 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 - ANSWER-BI & BI BO & BO BU & BD Cancelling Prism - ANSWER-BI & BO BD & BD BU & BU Prentice's Rule - 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 Vertical Imbalance - ANSWER-The difference in vertical prism power at the reading level in a pair of lenses. OC Height's by lens - ANSWER-SV = 1/2 of B Progressive = Fitting cross FT = 5mm above segment Vertex Compensation - 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 - 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 (+/-)