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20
OPERATION PROCEDURES
MEASUREMENT OF CONTACT LENSES
(1) Attachment of the column
Set up the column in the opening available on the chinrest as in (1) of "PRACTICE MEA-
SUREMENTS WITH THE TEST BALL".
Next, fill the hole in the contact lens holder with water and softly press the contact lens, that is
to be measured, against this section, with the face of the lens to be measured facing the out-
side.
The above left figure shows the measurement of the radius of curvature of the concave sur-
face, while the above right figure shows that of the convex surface. The contact lens will not
fall from the holder, even when it is turned upside down, because water fills the holder's
depression to maintain surface tension. The contact lens holder, with the contact lens, should
be placed softly on the column, as shown below.
(2) Correct position of the instrument to the contact lens
The operation undertaken here is the same as that explained in (2) of "PRACTICE MEA-
SUREMENTS WITH THE TEST BALL" on pg. 15, and should be followed according to those
instructions.
(3) Measurement
Measurement should be made in the same manner explained in (3) of "PRACTICE MEA-
SUREMENTS WITH THE TEST BALL".
However, compensation will be required in the measurement results for the radius of curvature
of the concave face. Therefore, refer to "Compensation Table for the Radius of Curvature of
the Concave Face" which is supplied with the instrument.
The compensation required, for example, is 0.02mm in the case of a 8.00mm radius of curva-
ture. Therefore, the compensation table should be utilized when the precision required neces-
sitates its use.
Contact lens
Water
Contact lens
Water
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