OCPP 102 2.4 UPDATED ACTUAL Questions and CORRECT Answers
1. Boxing system A technique that circumscribes a box about a lens or frame opening
2. Boxing system A standardized method of determining frame and lens measurements, allowing
the correct placement of prescription requirements.
3. Boxing system The standardized and generally used method specifying all measurements must
be taken from the geometric center or bevel apexes and must be expressed in
millimeters.
4. Datum system not used that much today. A and B measurements are taken at the verry center of
the lens but leads to inacurate measurement because this may not be the largest
value
5. A measurement The horizontal distance in millimeters between vertical tangents to the apex of the
bevel on the temporal and nasal edges of a spectacle, horizontal eyesize
6. B measurement The vertical distance in millimeters between the upper and lower horizontal tan-
gents to the apex of the bevel of a spectacle lens, vertical frame depth
7. Distance be- The horizontal distance along the 180 line between the lenses of an ophthalmic
tween lenses frame, the bridge size may or may not be the same as this measurement
(DBL)
8. Effective Diame- Twice the longest radius of the lens
ter (ED)
9. C size Measurement of the circumference of an ophthalmic lens; used primarily on lenses
only jobs
10. Eyewire groove The groove in a frame which holds the lens in place
, 11. datum line Used as a reference point for measurements, also known as the 180 line
12. Distance Be- The distance between the geometric centers of the lens opening of a frame, also
tween Centers referred to as frame PD, or FPD. Rarely the term GCD geometric centered distance
(DBC) is used. A measurement + DBL
13. Pupillary dis- The linear distance between the patient pupillary centers, measured either monoc-
tance (PD) ularly or binocularly
14. Optical Center Measured from the deepest portion of the eyewire to the point of the lens' optical
(OC) center location
15. segment width The linear measurement in millimeters of the widest horizontal plane of the near
segment
16. segment height The vertical distance in millimeters from the horizontal tangent at the lower finished
lens edge to the horizontal tangent at the top of the segment in a multifocal
spectacle lens
17. Decentration What does DEC stand for?
(DEC)
18. Decentration Horizontal displacement of the optical center to correspond with the patient's visual
(DEC) axis when viewing in the distance
19. DEC = (DBC - dis- How do you find binocular decentraton? (Formula)
tance PD)/2
20. Distance be- What does DBC stand for?
tween centers
21. RDEC = (DBC/2) How do you find monocular PD for the right eye? (Formula)
-RPD
2/7
1. Boxing system A technique that circumscribes a box about a lens or frame opening
2. Boxing system A standardized method of determining frame and lens measurements, allowing
the correct placement of prescription requirements.
3. Boxing system The standardized and generally used method specifying all measurements must
be taken from the geometric center or bevel apexes and must be expressed in
millimeters.
4. Datum system not used that much today. A and B measurements are taken at the verry center of
the lens but leads to inacurate measurement because this may not be the largest
value
5. A measurement The horizontal distance in millimeters between vertical tangents to the apex of the
bevel on the temporal and nasal edges of a spectacle, horizontal eyesize
6. B measurement The vertical distance in millimeters between the upper and lower horizontal tan-
gents to the apex of the bevel of a spectacle lens, vertical frame depth
7. Distance be- The horizontal distance along the 180 line between the lenses of an ophthalmic
tween lenses frame, the bridge size may or may not be the same as this measurement
(DBL)
8. Effective Diame- Twice the longest radius of the lens
ter (ED)
9. C size Measurement of the circumference of an ophthalmic lens; used primarily on lenses
only jobs
10. Eyewire groove The groove in a frame which holds the lens in place
, 11. datum line Used as a reference point for measurements, also known as the 180 line
12. Distance Be- The distance between the geometric centers of the lens opening of a frame, also
tween Centers referred to as frame PD, or FPD. Rarely the term GCD geometric centered distance
(DBC) is used. A measurement + DBL
13. Pupillary dis- The linear distance between the patient pupillary centers, measured either monoc-
tance (PD) ularly or binocularly
14. Optical Center Measured from the deepest portion of the eyewire to the point of the lens' optical
(OC) center location
15. segment width The linear measurement in millimeters of the widest horizontal plane of the near
segment
16. segment height The vertical distance in millimeters from the horizontal tangent at the lower finished
lens edge to the horizontal tangent at the top of the segment in a multifocal
spectacle lens
17. Decentration What does DEC stand for?
(DEC)
18. Decentration Horizontal displacement of the optical center to correspond with the patient's visual
(DEC) axis when viewing in the distance
19. DEC = (DBC - dis- How do you find binocular decentraton? (Formula)
tance PD)/2
20. Distance be- What does DBC stand for?
tween centers
21. RDEC = (DBC/2) How do you find monocular PD for the right eye? (Formula)
-RPD
2/7
