5-6
5) The ADD Readings are Higher than the Nominal Value.
Cause: Some progressive lenses may have a peak of ADD below the
near power circle. With these lenses, the ADD readings may be
higher than the nominal values.
Action: The ADD reading should be taken at the near point
marked on the lens blank. (The cursor may not change to
"
".)
After dispensing, marking do not exist. Read the ADD at
a spot located 20 mm below the center of the frame. (See
diagram below.) Note that in small frames, this location
may be beyond the extent of the frame.
In either case, make sure to take the ADD reading while
the cursor stays in the progressive zone.
The Measurement Position of the Near Point
about 20mm
Center of the frame (Fitting cross)
measurement position of
near point
lens table
5.1 TROUBLESHOOTING GUIDE
Near power circle
Peak of ADD
Distance power circle
ADD (nominal)
ADD (measurement)
ADD (measurement) > ADD (nominal)
Power
Location
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