ABO Practical(ABO Practical broken down based on the ABO-NCLE practical Exam Candidate HandbookPractical Test Specifications sheet)
Single Vision
corrects for one distance
Multifocal
Corrects with two or more prescriptions (or 'powers')
00:05
01:09
Bifocal
lens having two fo...
ABO Practical( ABO Practical broken down based on the ABO-NCLE practical Exam Candidate HandbookPractical Test Specifications sheet)
Single Vision - Answer corrects for one distance
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) ABO Practical( ABO Practical broken down based on the ABO-NCLE practical Exam Candidate HandbookPractical Test Specifications sheet)
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
Frame PD is found by adding A+DBL
Power in Oblique Meridians - 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
Lensmeter - Answer 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 - Answer lens clock, calipers, millimeter ruler, circumference gauge
Lens Clock - Answer is used to measure the surface powers base curve of a lens
Lens Calipers - Answer Measures thickness of lenses in mm
Millimeter ruler - Answer measures interpupillary distance, or seg heights, or OC heights
Circumference gauge - Answer For quick and accurate measurements of lenses or patterns.
Corneal reflex Pupilometer - Answer for precisely measuring and digitally recording pupillary distances. Used for measuring of monocular and binocular
Hand Tools - Answer Screwdrivers, needle-nose pliers, tweezers, files
scratchless screwdriver - Answer for working on drill mount or facetted lenses
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