Abstract
Boxing system is a standard for frame and lens measurement that is based on the
idea of drawing an imaginary box around a lens shape with the box’s sides
tangent to the outer most edges of the shape. This helps in the cutting of a
lens with the use of set out standard measurement which are “A” Measurement,
“B” Measurement,
Datum Line, Geometric Center (GC), Distance Between Lenses (DBL), etc.
idea of drawing an imaginary box around a lens shape with the box’s sides
tangent to the outer most edges of the shape. This helps in the cutting of a
lens with the use of set out standard measurement which are “A” Measurement,
“B” Measurement,
Datum Line, Geometric Center (GC), Distance Between Lenses (DBL), etc.
Overview on boxing system
The
boxing system to provide a standard for frame and lens
measurement that is based on the idea of drawing an imaginary box around a lens
shape with the box’s sides tangent to the outer most edges of the shape. The
system uses the sides of the boxes as reference points for the standard system
of measurements.
boxing system to provide a standard for frame and lens
measurement that is based on the idea of drawing an imaginary box around a lens
shape with the box’s sides tangent to the outer most edges of the shape. The
system uses the sides of the boxes as reference points for the standard system
of measurements.
Measuring
standards in boxing system
standards in boxing system
·
“A” Measurement: The
horizontal distance between the vertical sides of the box. The A measurement is
also commonly known as the eyesize.
“A” Measurement: The
horizontal distance between the vertical sides of the box. The A measurement is
also commonly known as the eyesize.
·
“B” Measurement: The
vertical distance between the furthest top and bottom edges of the lens shape
or the distance between the horizontal sides of the box.
“B” Measurement: The
vertical distance between the furthest top and bottom edges of the lens shape
or the distance between the horizontal sides of the box.
·
Datum Line: The horizontal line
that runs through the vertical center of the frame.
Datum Line: The horizontal line
that runs through the vertical center of the frame.
·
Geometric Center (GC): The
intersection of the Datum Line and horizontal centers of each lens shape.
Geometric Center (GC): The
intersection of the Datum Line and horizontal centers of each lens shape.
·
Distance Between Lenses (DBL):
The shortest distance between the nasal edges of each lens or the distance
between boxes. DBL is also commonly referred to as bridge
size.
Distance Between Lenses (DBL):
The shortest distance between the nasal edges of each lens or the distance
between boxes. DBL is also commonly referred to as bridge
size.
·
Distance Between Centers (DBC): The
horizontal distance between the geometric centers of the lenses. DBC is also
known as the
Distance Between Centers (DBC): The
horizontal distance between the geometric centers of the lenses. DBC is also
known as the
·
Geometric Center Distance (GCD),
but more commonly referred to as the frame PD. In theory the DBC can be calculated by adding the “A”
Measurement to the DBL as marked on the frame, however in practice the
calculation may differ from the actual measurement.
Geometric Center Distance (GCD),
but more commonly referred to as the frame PD. In theory the DBC can be calculated by adding the “A”
Measurement to the DBL as marked on the frame, however in practice the
calculation may differ from the actual measurement.
Note: Frames are typically marked for size, for
example: 54-18, where 54 is the “A” Measurement and 18 is the DBL.
example: 54-18, where 54 is the “A” Measurement and 18 is the DBL.
·
Effective Diameter (ED): Twice
the distance from the geometric center of the lens furthest edge of the lens
shape. The ED can also be defined as the smallest diameter lens that would
cutout, if the frame’s geometric center matched the lenses optical center. ED
is used in combination with decentration distance to select the minimum lens
blank size required to fit a given frame.
Effective Diameter (ED): Twice
the distance from the geometric center of the lens furthest edge of the lens
shape. The ED can also be defined as the smallest diameter lens that would
cutout, if the frame’s geometric center matched the lenses optical center. ED
is used in combination with decentration distance to select the minimum lens
blank size required to fit a given frame.
·
Seg Height: The vertical
distance between the bottom edge of the box and the top of the bifocal or
trifocal segment
Seg Height: The vertical
distance between the bottom edge of the box and the top of the bifocal or
trifocal segment
·
Seg Drop: The vertical
distance between the Datum line and the top of the bifocal or trifocal segment
Overall
Seg Drop: The vertical
distance between the Datum line and the top of the bifocal or trifocal segment
Overall
·
Temple Length (OTL):
The running distance between the middle of the center barrel screw hole and the
end of the temple.
Temple Length (OTL):
The running distance between the middle of the center barrel screw hole and the
end of the temple.
·
Length to Bend (LTB): The
distance between the center of the barrel and the middle of the temple bend.
Length to Bend (LTB): The
distance between the center of the barrel and the middle of the temple bend.
·
Front to Bend (FTB): The
distance between the plane of the front of the frame and the temple bend. Used
if there is a significant distance between the frame front and the beginning of
the temple
Front to Bend (FTB): The
distance between the plane of the front of the frame and the temple bend. Used
if there is a significant distance between the frame front and the beginning of
the temple
References
Stevenson,
K. (2007). The basics of optics. New York: Essilor Academy.
K. (2007). The basics of optics. New York: Essilor Academy.
