26
11625-101-Rev. L
Taking Measurements
(continued)
Rotary Prisms
1. Each Rotary Prism Unit (loupe) has a range of 20 .
2. Paired, prisms give 40 in any base direction.
3. The scale is marked in broad divisions of one prism
diopter ( ).
4. The Rotary Prism Unit and the Cross Cylinder Unit
are attached to the Turret Assembly. The Turret As-
sembly rotates to locate either the Rotary Prism Unit
or the Cross Cylinder Unit in front of the patient’s eye.
When testing for prism rotate the Rotary Prism Unit in
front of the eye. With the Rotary Prism Unit in front
of the patient’s eye, the unit can be oriented to deter-
mine base up, base down, base in, or base out prism.
Refer to Figure IU-6.
5. The Finger Roll Knob rotates the prism
lenses inside the Rotary Prism Unit and
varies the magnitude of prism.
Refer to Figure IU-7.
• When the Finger Roll Knob is located
at either the top or bottom of the Ro-
tary Prism Unit, the prism change will
be base in or base out as the Finger
Roll Knob is rotated.
• When the Finger Roll Knob is located
on either the left or right side of the
Rotary Prism Unit, the prism change
will be base up or base down as the
Finger Roll Knob is rotated.
Note:
With the Rotary Prism set for introducing base in or base out prism, the arrowhead posi-
tioned nasally from 0 denotes base in prism.
Instructions for Use
(continued)
Figure IU-7 Rotary Prism Unit
Finger Roll Knob
Figure IU-6 Finger Roll Knob
Turret
Assembly
Rotary
Prism Unit
Cross
Cylinder
Assembly
