Power Calculation For Toric Lenses - OCULUS Easygraph 70620 Instruction Manual

Page 56
The Refraction Module contains the following fields:
• Spectacle power
Entry of power values and automatic calculation of
corneal vertex refraction (CVD=0).
• Test lens
Selection of contact lens parameters:
The curvature of the posterior surface of the
contact lens has been measured by means of the
fluo image and is therefore only displayed here.
This curvature can only be changed through
contact lens fitting (fluo image simulation).
• Comment
Here the user can enter any text he desires. The
text is saved together with the power values and
thus remains available for later occasions.
Further contact lens parameters can be entered in
the "Test lens toric" field:
Incl.: Here you can change the inclination (rotation)
of the contact lens (cf. page 52). Initially the
inclination is such that the flat meridian of the
posterior surface of the contact lens corresponds to
that of the cornea. This is where to correct the
rotation of the lens in the event that the two flat
meridians do not coincide.
Instruction Manual Easygraph

7.5.3.3.1 Power Calculation for Toric Lenses

• Cornea
This field displays the keratometric values of the
cornea measured by means of the Easygraph:
r0 (mm): central radii
Cor.Ast.: corneal astigmatism (central)
Axis (Rf): axis of the flat meridian
• Remaining power (expected)
This field shows the "Expected remaining
power" described above.
Clicking the [Back] button exits the power calculation
module and transfers the new values to the "Power
calculation" field of the contact lens fitting dialog
box.
Any change in inclination automatically leads to a
recalculation of the fluo image after exiting the power
calculation module ( [Back] button).
n: The refractive index n of the contact lens material
determines the degree of induced astigmatism in
toric lenses, and hence their toric effect. This is why
the contact lens material or the refractive index has
to be specified.