ABO Practical Exam Questions And Answers

ABO Practical Exam Questions And Answers Single Vision - ANS corrects for one distance Multifocal - ANS Corrects with two or more prescriptions (or 'powers') Bifocal - ANS lens having two focus strengths Trifocal - ANS pertaining to having three focus strengths Calculating Prismatic Effects - ANS 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 - ANS BI & BI BO & BO BU & BD Cancelling Prism - ANS BI & BO BD & BD BU & BU Prentice's Rule - ANS 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 - ANS The difference in vertical prism power at the reading level in a pair of lenses. OC Height's by lens - ANS SV = 1/2 of B Progressive = Fitting cross FT = 5mm above segment Vertex Compensation - ANS 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 - ANS De= Dl/(1 + d xDl) De= diopter effective value of error created D/= lens power (given power)