OPTICIAN CORE EXAM 2026 TEST QUESTIONS AND
SOLUTIONS RATED A+
✔✔DBC - ✔✔Measurement between the center of one lens and the center other lens
across the bridge. A + DBL= DBC
✔✔PC - ✔✔Geometric center of the "box". Knowing this helps you get the center of the
lens correctly placed into the center of the frame.
✔✔Frame Center - ✔✔In the imaginary "box," you can draw lines from one corner to the
opposite corner, making an X. The point where the lines cross is the frame center.
✔✔FPD - ✔✔Frame pupillary distance. This measurement is the same as the DBC.
✔✔Pattern difference - ✔✔Has to do with the shape of the pattern and lens, or A-B.
✔✔A measurement - ✔✔The measurement across the imaginary "box". The
measurement from vertical tangent to bevel, horizontally.
✔✔B measurement - ✔✔The measurement up and down from the horizontal tangent to
the bevel. A vertical measurement.
✔✔C measurement - ✔✔The measurement across the geometric center line. The only
time that the C measurement is the same as the A measurements when the lens is the
widest at the line. Most of the time the A measurement will be more than the C.
✔✔ED - ✔✔Effective diameter. This measurement is needed to determine the
appropriate lens blank size.
✔✔Measuring the Correct temple length - ✔✔Measure from the screw hole at the center
barrel all the way to the end of the temple, including around the ear. be sure to measure
on the middle of the temple length and not the edges.
✔✔Proposed working distance - ✔✔This is the measurement between you and the
patient when taking the PD measurement.
✔✔Crest angle of the bridge - ✔✔The angle that you can see when looking at the facial
profile. This angle should be parallel to the angle of the nose.
✔✔Fresnel lens - ✔✔A design of lens where there is a central point in the middle and
concentric ridges going out from there. The ridges have a prism effect.
✔✔Anisometropia - ✔✔A condition in which one eye differs significantly in refractive
power from the other eye.
, ✔✔Aperture - ✔✔An opening or hole that admits only a portion of light from a given
source or sources.
✔✔Apex - ✔✔The junction point at which the two nonparallel surfaces of a prism meet.
✔✔Astigmatism - ✔✔The presence of two different curves on a single refracting surface
on or within the eye causing light to focus at two lime images instead of a single point.
✔✔Axis of a cylinder - ✔✔An imaginary reference line used to specify cylinder or
spherocylinder lens orientation and corresponding to the median perpendicular to that of
maximum cylinder power.
✔✔Barrel - ✔✔The housing for a screw on a pair of glasses.
✔✔Base - ✔✔In a prism, the edge of maximum surface separation opposite the apex.
✔✔Bevel - ✔✔The angled edge of the spectacle lens.
✔✔Blocker - ✔✔The device used to place a block on the lens in order to hold the lens in
place during the edging process.
✔✔Block - ✔✔Attaches to the surface of a lens in order to hold it in place during the
surfacing or edging process.
✔✔Vernier Caliper - ✔✔A hand-held width measuring device with a short graduated
scale that slides along a longer graduated scale allowing a measure of fractional parts
or decimals.
✔✔Carrier - ✔✔The optically unusable outer portion of a lenticular lens that "carries" the
optically useable central portion.
✔✔Centration - ✔✔The act of positioning a lens for edging such that it will optically
conform to prescription specifications.
✔✔Rotational center - ✔✔The point on a pattern around which it rotates during edging.
✔✔Colmascope - ✔✔An instrument that utilizes polarized light to show strain patterns in
glass or plastic.
✔✔Concave - ✔✔An inward-curved surface
✔✔Convergence - ✔✔An inward turning of the eyes, as when looking at a near object.
The action of light rays traveling toward a specific real image point.
SOLUTIONS RATED A+
✔✔DBC - ✔✔Measurement between the center of one lens and the center other lens
across the bridge. A + DBL= DBC
✔✔PC - ✔✔Geometric center of the "box". Knowing this helps you get the center of the
lens correctly placed into the center of the frame.
✔✔Frame Center - ✔✔In the imaginary "box," you can draw lines from one corner to the
opposite corner, making an X. The point where the lines cross is the frame center.
✔✔FPD - ✔✔Frame pupillary distance. This measurement is the same as the DBC.
✔✔Pattern difference - ✔✔Has to do with the shape of the pattern and lens, or A-B.
✔✔A measurement - ✔✔The measurement across the imaginary "box". The
measurement from vertical tangent to bevel, horizontally.
✔✔B measurement - ✔✔The measurement up and down from the horizontal tangent to
the bevel. A vertical measurement.
✔✔C measurement - ✔✔The measurement across the geometric center line. The only
time that the C measurement is the same as the A measurements when the lens is the
widest at the line. Most of the time the A measurement will be more than the C.
✔✔ED - ✔✔Effective diameter. This measurement is needed to determine the
appropriate lens blank size.
✔✔Measuring the Correct temple length - ✔✔Measure from the screw hole at the center
barrel all the way to the end of the temple, including around the ear. be sure to measure
on the middle of the temple length and not the edges.
✔✔Proposed working distance - ✔✔This is the measurement between you and the
patient when taking the PD measurement.
✔✔Crest angle of the bridge - ✔✔The angle that you can see when looking at the facial
profile. This angle should be parallel to the angle of the nose.
✔✔Fresnel lens - ✔✔A design of lens where there is a central point in the middle and
concentric ridges going out from there. The ridges have a prism effect.
✔✔Anisometropia - ✔✔A condition in which one eye differs significantly in refractive
power from the other eye.
, ✔✔Aperture - ✔✔An opening or hole that admits only a portion of light from a given
source or sources.
✔✔Apex - ✔✔The junction point at which the two nonparallel surfaces of a prism meet.
✔✔Astigmatism - ✔✔The presence of two different curves on a single refracting surface
on or within the eye causing light to focus at two lime images instead of a single point.
✔✔Axis of a cylinder - ✔✔An imaginary reference line used to specify cylinder or
spherocylinder lens orientation and corresponding to the median perpendicular to that of
maximum cylinder power.
✔✔Barrel - ✔✔The housing for a screw on a pair of glasses.
✔✔Base - ✔✔In a prism, the edge of maximum surface separation opposite the apex.
✔✔Bevel - ✔✔The angled edge of the spectacle lens.
✔✔Blocker - ✔✔The device used to place a block on the lens in order to hold the lens in
place during the edging process.
✔✔Block - ✔✔Attaches to the surface of a lens in order to hold it in place during the
surfacing or edging process.
✔✔Vernier Caliper - ✔✔A hand-held width measuring device with a short graduated
scale that slides along a longer graduated scale allowing a measure of fractional parts
or decimals.
✔✔Carrier - ✔✔The optically unusable outer portion of a lenticular lens that "carries" the
optically useable central portion.
✔✔Centration - ✔✔The act of positioning a lens for edging such that it will optically
conform to prescription specifications.
✔✔Rotational center - ✔✔The point on a pattern around which it rotates during edging.
✔✔Colmascope - ✔✔An instrument that utilizes polarized light to show strain patterns in
glass or plastic.
✔✔Concave - ✔✔An inward-curved surface
✔✔Convergence - ✔✔An inward turning of the eyes, as when looking at a near object.
The action of light rays traveling toward a specific real image point.
