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Introduc.DIr
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00075_Field_75.txt
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1997-10-29
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591b
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20 lines
CYLINDRICAL PRISM STABILIZED LENSES
With a hydrogel lens the cylinder can be generated on either the front or back surface.
The cylindrical power and axis is
specified in the same way as with
spectacles except the reference
for the cylinder axis is the
base-apex line of the prism. When
specifying the axis it is assumed
that the base-apex line is in the
90 degree meridian.
On the eye the base-apex of the lens
may rotate away from vertical
meridian. During the fitting this rotation
must be taken into account when the lens power is ordered.