ABO Practical (with Complete Solutions)

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