ABO EXAM QUESTIONS AND CORRECT DETAILED ANSWERS
WITH RATIONALES (VERIFIED ANSWERS) |ALREADY GRADED
A+||NEWEST VERSION
Terms in this set (85)
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
obtained at the center of an optical lens by producing a
difference in edge thickness, either by grinding the back
Calculating Prismatic Effects
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
, BI &
Compounding Prism BI
BO &
BO
BU &
BD
BI &
Cancelling Prism BO
BD &
BD
BU &
BU
P=hcm x D
P=amount of prism
Prentice's Rule created h= number of
cm OC moved
cm= centimeters (convert to mm,
divide by 10) D= power in
meridian with error
Vertical Imbalance The difference in vertical prism power at the reading level in a pair of
lenses.
SV = 1/2 of B
OC Height's by lens Progressive =
Fitting cross FT =
5mm above segment
A plus lens when moved farther from the eye gains in
Vertex Compensation
plus power Distance is 0 with CL because they are
on the eye
De= Dl/(1 + d xDl)
De= diopter effective value of
error created D/= lens power
Vertex compensation Formula
(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 PD
Vertical Centration OC
Given PD/OC - Human PD/OC=
Horizontal & Vertical Centration
Formula mm moved Frame PD is found
WITH RATIONALES (VERIFIED ANSWERS) |ALREADY GRADED
A+||NEWEST VERSION
Terms in this set (85)
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
obtained at the center of an optical lens by producing a
difference in edge thickness, either by grinding the back
Calculating Prismatic Effects
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
, BI &
Compounding Prism BI
BO &
BO
BU &
BD
BI &
Cancelling Prism BO
BD &
BD
BU &
BU
P=hcm x D
P=amount of prism
Prentice's Rule created h= number of
cm OC moved
cm= centimeters (convert to mm,
divide by 10) D= power in
meridian with error
Vertical Imbalance The difference in vertical prism power at the reading level in a pair of
lenses.
SV = 1/2 of B
OC Height's by lens Progressive =
Fitting cross FT =
5mm above segment
A plus lens when moved farther from the eye gains in
Vertex Compensation
plus power Distance is 0 with CL because they are
on the eye
De= Dl/(1 + d xDl)
De= diopter effective value of
error created D/= lens power
Vertex compensation Formula
(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 PD
Vertical Centration OC
Given PD/OC - Human PD/OC=
Horizontal & Vertical Centration
Formula mm moved Frame PD is found
