OCULUS Easygraph 70620 Instruction Manual page 67

2. The Periphery
The periphery of contact lenses must also be
entered after the base parameters have been
defined. Two peripheral zones, each with 3
parameters, can be entered:
• b1: Width of Zone 1:
• r1: Curvature of Zone 1
• dr1: Differences
in
meridians (for toric lenses)
• b2: Width of Zone 2
• r2: Curvature of Zone 2
• dr2: Differences
in
meridians (for toric lenses)
These parameters are used to define bevelled
lenses and those with more than one curvature.
If the curvature of a zone remains constant
throughout the entire series, it can be entered after
• Example:
Bevelled lens with symmetrical axes of rotation (0.8 mm greater than the centralradii)
b1 = constant b1=0.25
r1=r0*A+B A=1.00
dr1 = constant
dr1=0
b2 = constant b2=0.00
r2=r0*A+B A=1.00
dr2 = constant
dr2=0
• Example:
Bevelled lens with symmetrical axes of rotation (1.5 times central radius)
b1 = constant b1=0.25
r1=r0*A+B A=1.50
dr1 = constant
dr1=0
b2 = constant b2=0.00
r2=r0*A+B A=1.50
dr2 = constant
dr2=0
Instruction Manual Easygraph
curvature of the main
curvature of the main
B=0.80
B=0.80
B=0.00
B=0.00
clicking the "r1 = constant" or "r2 = constant"
buttons.
If the curvature of the zones is not constant but
depends on the central radius, it can be defined by
using the formula: r1=r0*A+B. The parameters A
and B can be entered after this formula has been
clicked.
For example, the user can define the curvature of a
marginal zone as being invariably 0.8 mm greater
than the central radius (A=1 / B=0.8), or invariably
1.5 times the central radius (A=1.5 / B=0).
If toric lenses are to be defined, the "dr1=dr0*r1/r0"
/ "dr2=dr0*r2/r0" button should be clicked. This
copies the relationships of the central radii to the
periphery.
The value b2 must be specified as zero if the second
zone is not used;
parameters must have the same settings as those of
Zone 1. The value b1 may not be set to zero.
Page 67
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