ABO Practical final Exam Questions and CORRECT Answers
GRADED TO PASS!!!
Single Vision
corrects for one distance
Multifocal
Corrects with two or more prescriptions (or 'powers')
Bifocal
lens having two focus strengths
Trifocal
pertaining to having three focus strengths
Calculating Prismatic Effects
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
BI & BI
BO & BO
BU & BD
Cancelling Prism
BI & BO
BD & BD
BU & BU
Prentice's Rule
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
Page 1 of 2
GRADED TO PASS!!!
Single Vision
corrects for one distance
Multifocal
Corrects with two or more prescriptions (or 'powers')
Bifocal
lens having two focus strengths
Trifocal
pertaining to having three focus strengths
Calculating Prismatic Effects
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
BI & BI
BO & BO
BU & BD
Cancelling Prism
BI & BO
BD & BD
BU & BU
Prentice's Rule
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
Page 1 of 2
