ABO Practical UPDATED Exam Questions
and CORRECT Answers only
Single Vision - Correct Answer- corrects for one distance
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
Horizontal & Vertical Centration Formula - Correct Answer- Given PD/OC - Human
PD/OC= mm moved
Frame PD is found by adding A+DBL
Power in Oblique Meridians - Correct Answer- Dt= (sina)²x Dc +Ds
Dt= Total Power we need
(sina)²= degree we have degree we need
Dc= cylinder power
Ds= sphere power
and CORRECT Answers only
Single Vision - Correct Answer- corrects for one distance
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
Horizontal & Vertical Centration Formula - Correct Answer- Given PD/OC - Human
PD/OC= mm moved
Frame PD is found by adding A+DBL
Power in Oblique Meridians - Correct Answer- Dt= (sina)²x Dc +Ds
Dt= Total Power we need
(sina)²= degree we have degree we need
Dc= cylinder power
Ds= sphere power
