ABO PRACTICAL | VERIFIED ACCURATE STUDY GUIDE |
LATEST UPDATED
Single Vision - Answers -corrects for one distance
Multifocal - Answers -Corrects with two or more prescriptions (or 'powers')
Bifocal - Answers -lens having two focus strengths
Trifocal - Answers -pertaining to having three focus strengths
Calculating Prismatic Effects - Answers -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 - Answers -BI & BI
BO & BO
BU & BD
Cancelling Prism - Answers -BI & BO
BD & BD
BU & BU
Prentice's Rule - Answers -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 - Answers -The difference in vertical prism power at the reading
level in a pair of lenses.
OC Height's by lens - Answers -SV = 1/2 of B
Progressive = Fitting cross
FT = 5mm above segment
Vertex Compensation - Answers -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 - Answers -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 - Answers -PD
Vertical Centration - Answers -OC
Horizontal & Vertical Centration Formula - Answers -Given PD/OC - Human PD/OC=
mm moved
Frame PD is found by adding A+DBL
Power in Oblique Meridians - Answers -Dt= (sina)²x Dc +Ds
Dt= Total Power we need
(sina)²= degree we have degree we need
Dc= cylinder power
Ds= sphere power
Lensmeter - Answers -is an ophthalmic instrument. It is mainly used by optometrists
and opticians to verify the correct prescription in a pair of eyeglasses, to properly orient
and mark uncut lenses, and to confirm the correct mounting of lenses in spectacle
frames. (also known as a focimeter or vertometer)
Lens Measurement Devices - Answers -lens clock, calipers, millimeter ruler,
circumference gauge
Lens Clock - Answers -is used to measure the surface powers base curve of a lens
Lens Calipers - Answers -Measures thickness of lenses in mm
Millimeter ruler - Answers -measures interpupillary distance, or seg heights, or OC
heights
Circumference gauge - Answers -For quick and accurate measurements of lenses or
patterns.
Corneal reflex Pupilometer - Answers -for precisely measuring and digitally recording
pupillary distances. Used for measuring of monocular and binocular
Hand Tools - Answers -Screwdrivers, needle-nose pliers, tweezers, files
scratchless screwdriver - Answers -for working on drill mount or facetted lenses
pickup screwdriver - Answers -jaws with spring tension to hold screws while you put
them in place, available with either type blade
LATEST UPDATED
Single Vision - Answers -corrects for one distance
Multifocal - Answers -Corrects with two or more prescriptions (or 'powers')
Bifocal - Answers -lens having two focus strengths
Trifocal - Answers -pertaining to having three focus strengths
Calculating Prismatic Effects - Answers -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 - Answers -BI & BI
BO & BO
BU & BD
Cancelling Prism - Answers -BI & BO
BD & BD
BU & BU
Prentice's Rule - Answers -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 - Answers -The difference in vertical prism power at the reading
level in a pair of lenses.
OC Height's by lens - Answers -SV = 1/2 of B
Progressive = Fitting cross
FT = 5mm above segment
Vertex Compensation - Answers -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 - Answers -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 - Answers -PD
Vertical Centration - Answers -OC
Horizontal & Vertical Centration Formula - Answers -Given PD/OC - Human PD/OC=
mm moved
Frame PD is found by adding A+DBL
Power in Oblique Meridians - Answers -Dt= (sina)²x Dc +Ds
Dt= Total Power we need
(sina)²= degree we have degree we need
Dc= cylinder power
Ds= sphere power
Lensmeter - Answers -is an ophthalmic instrument. It is mainly used by optometrists
and opticians to verify the correct prescription in a pair of eyeglasses, to properly orient
and mark uncut lenses, and to confirm the correct mounting of lenses in spectacle
frames. (also known as a focimeter or vertometer)
Lens Measurement Devices - Answers -lens clock, calipers, millimeter ruler,
circumference gauge
Lens Clock - Answers -is used to measure the surface powers base curve of a lens
Lens Calipers - Answers -Measures thickness of lenses in mm
Millimeter ruler - Answers -measures interpupillary distance, or seg heights, or OC
heights
Circumference gauge - Answers -For quick and accurate measurements of lenses or
patterns.
Corneal reflex Pupilometer - Answers -for precisely measuring and digitally recording
pupillary distances. Used for measuring of monocular and binocular
Hand Tools - Answers -Screwdrivers, needle-nose pliers, tweezers, files
scratchless screwdriver - Answers -for working on drill mount or facetted lenses
pickup screwdriver - Answers -jaws with spring tension to hold screws while you put
them in place, available with either type blade
