The characters plus and minus in cyclophoria merely refer to plus as signifying a tendency toward the temporal side; minus indicating a tendency toward the nasal side. This has no bearing on “convex” and “concave,” which are frequently designated as “plus” and “minus.”
The test for cyclophoria is particularly essential, proving of utmost importance where the patient requires an astigmatic correction with the cylinder axis in oblique meridian. The case should then be investigated in every instance by making a thorough and separate test of each eye for cyclophoria.
In a case where cyclophoria is determined, the trouble may be caused by the functioning of other muscles, through the drain of nerve force, thus disturbing the harmony of every muscle action.
Cyclophoria is frequently caused by an imbalance of two recti, giving an oblique pull. In most cases, it is merely necessary to release the torsion, as described in the following chapter.
Chapter XIV
CYCLODUCTION TEST
Made With the Combined Use of
the Two Maddox Rods
Having determined that cyclophoria exists, as previously outlined, the next step would be to make a cycloduction test, or a test of the oblique muscles individually. Maddox rods, both red and white, should be placed in position with the rods horizontal—the plus and minus sign at 90 degrees on the scale ([Fig. 37]). The patient’s attention should be directed to the usual muscle-testing spot of light, when a vertical band of light will appear to the patient, as shown in [Fig. 38].
Fig. 37—(A. and B.)—Primary position of combined use of both Maddox rods for determining cycloduction test.
Fig. 38