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OPTOMETRY
ACCURATE MEASUREMENT OF THE SPHERICAL POWER (RED-GREEN
TEST)
1 Next, make an accurate measurement of spherical power. Set the red-green chart, and
the spherical movable mode is automatically set.
Ask the patient which side is seen better, red or green.
He answers the green side is seen a little better. Since this means that myopia is a little
strong (or hyperopia is a little weak), increase the spherical power by +0.25D.
2 Ask the patient again which side is more clearly visible. He answers the red side is seen a
little better. This means that myopia is a little weak (or hyperopia is a little strong). -0.25D
is to be added to the spherical power but the condition will return to the original status. This
means that the spherical power of Mr. A lies between -1.50D and -1.75D, namely -1.62D.
Such a lens should be specially ordered. In general, the weaker spherical power for myo-
pia (or stronger spherical power for hyperopia) is applied.
3 The measurement of the right eye is finished. Sum up the lens refractive power. The dis-
played measured values for the right eye are shown below.
Spherical (spherical power) : -1.50
Astigmatism (astigmatic power): -0.50
Axis (astigmatic axis) : 100
The above values are summed up as:
Right eye : S-1.50D C-0.50D A100°
4 Next, measure the left eye. Occlude the right eye and make the left eye uncovered. The
movable mode of the left eye is accessed. In the same way as the right eye, carry out the
procedure from "OPTOMETRY BY FOGGING METHOD" to "ACCURATE MEASURE-
MENT OF THE SPHERICAL POWER (RED-GREEN TEST)".
The values for the left eye of Mr. A are summed up as:
Left eye : S-2.00D C-0.50D A170°
5 The measurement of the right and left eyes is completed. As each eye is measured inde-
pendently, the balance of both eyes will be examined by "binocular balance test".
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