User's Manual

42 CDC-1 -----------------------------------------------------------------------------------------------------------------------------------
9.5. Red/Green Test
Title
Content
Purpose
To determine the correcting spherical power
Chart
Aux. Lens
None
Polarized Filter
Cross Cylinder(Fixed at 90)
Procedure
① (Occlude one eye that’s not to be examined).
② Add about 0.5D for fogging if necessary.
③ Ask the patient which side looks clearer, on the green or on the red. Add plus or minus
power until the patient sees the both side the same.
- Add plus power if the letters on green side is clearer.
- Add minus power if the letters on red side is clearer.
③ (Cross Cylinder) Ask the patient if the horizontal lines and the vertical lines are the same
in thickness.
- Increase the spherical power by 0.25D if the horizontal lines are thicker.
- Decrease the spherical power by 0.25D if the vertical lines are thicker.
9.6. Cross Cylinder Test for Axis
Title
Content
Purpose
To refine the correcting cylinder axis
Chart
Aux. Lens
Jackson Cross Cylinder (±0.25 or ±0.50)
Procedure
① Occlude one eye that’s not to be examined.
② Place the JCC lens before the eye such that its axes straddle at 45 degrees angles the
correcting cylinder axis.
③ Find the exact cylinder axis by repeating circulating the JCC lens and asking the patient
which view is sharper or less blurry until the two views are the same in sharpness.
- Plus the axis if the view before circulation is sharper.
- Minus the axis if the view after circulation is sharper.