Potec PDR-7000 - Cross Grid Test for Far Vision

PDR-7000 Operation Manual
4.4.2 Cross grid test for far vision
Use: Spherical refinement
Chart: Cross-grid
Auxiliary lens: ±0.50 D cross cylinder lens (Fixed with the axis set at 90º.)
Ideal appearance: The sharpness of the horizontal and vertical lines appears
equal.
[Procedure example]
1. Press
2. Pres s or to occlude either measuring
window.
3. Present the cross-grid chart.
Press
The cross cylinder lens of ±0.50 D is placed in the specified measuring window.
4. Ask a patient, “Which are sharper, the horizontal or vertical line?”
The horizontal and vertical lines appear equal.  The spherical power is properly
refined.
The horizontal lines are sharper.  In the case of myopia, the spherical power is over-
minused.In the case of hyperopia, the spherical power is undercorrected.
The vertical lines are sharper.  In the case of myopia, the spherical power is under-
minused.In the case of hyperopia, the spherical power is overcorrected.
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