ABO PRACTICAL COMPREHENSIVE
EXAMINATION TEST COMPLETE
QUESTIONS WITH ACCURATE SOLUTIONS
●● 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 (+/-)
- to d means moves away
●● Horizontal Centration
Answer: PD
●● Vertical Centration
Answer: OC
●● Horizontal & Vertical Centration Formula
Answer: Given PD/OC - Human PD/OC= mm moved
EXAMINATION TEST COMPLETE
QUESTIONS WITH ACCURATE SOLUTIONS
●● 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 (+/-)
- to d means moves away
●● Horizontal Centration
Answer: PD
●● Vertical Centration
Answer: OC
●● Horizontal & Vertical Centration Formula
Answer: Given PD/OC - Human PD/OC= mm moved
