ABO Practical Exam Question and Answer
(2026/2027) | Updated Questions and
Correct Answers | A+ Verified
• 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
• 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
• Horizontal Centration . CORRECT ANSWER: PD
• Vertical Centration . CORRECT ANSWER: OC
(2026/2027) | Updated Questions and
Correct Answers | A+ Verified
• 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
• 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
• Horizontal Centration . CORRECT ANSWER: PD
• Vertical Centration . CORRECT ANSWER: OC
