CHAPTER XIII. Cyclophoria

CYCLOPHORIA

MADE WITH MADDOX RODS AND ROTARY PRISMS

Cyclophoria, a condition affecting the oblique muscles of the eye, is caused by its rotation. It is detected in the following manner by the combined use of the red and white Maddox rods and the rotary prism.

Darken the room and direct the patient’s attention to the usual muscle-testing spot of light, located approximately twenty feet away and on a direct plane with the patient’s eye. The optical correction, if one is required, should always be left in place—just as in making other previously described muscle tests.

The rotary prism should then be brought before the patient’s right eye with the handle-pointing upward and with zero graduations horizontal. The indicator or red line should then be rotated upward from zero to eight upon the prism scale, creating the equivalent of a prism of 8 diopters with base up (Fig. 29). This normally caused diplopia, although in some cases it may be necessary to place the prism at 10 or 12 degrees before diplopia is produced.

The red Maddox rod should then be brought into operative position before the patient’s left eye (Fig. 30a) and the white Maddox rod before the patient’s right eye, (Fig. 30b) setting each one so that the rods lie in a vertical position with their white line on the large red zero (0).

The patient should now see two separate and distinct streaks of light, one appearing below the other.

RIGHT EYE LEFT EYE

Fig. 31 Fig. 34

NO CYCLOPHORIA NO CYCLOPHORIA]

+ CYCLOPHORIA + CYCLOPHORIA]

- CYCLOPHORIA - CYCLOPHORIA

Figs. 31-36—Diagram showing how streaks appear to patient, as produced by the Maddox rods in testing for cyclophoria.]

Should there be no cyclophoria of the right eye, the streaks will appear in a horizontal plane parallel to each other (Fig. 31).

Should the red streak appear horizontally to the left eye, and the white streak seen by the right eye appear at an angle therewith, cyclophoria of the right eye would be indicated (Fig. 32).

In brief, should the white streak dip towards the patient’s left side, the case would be one of right plus cyclophoria (Fig. 32); whereas right minus cyclophoria would be indicated should the white streak dip to the patient’s right side (Fig. 33).

Next, setting the rotary prism of 8 degrees, placed base up before the patient’s left eye, the red streak should appear below the white one. Should the two streaks appear horizontally, parallel with each other, there would be no cyclophoria of the left eye (Fig. 34).

If, however, the upper or white streak should appear horizontal, and the lower or red streak at an angle therewith dipping toward the patient’s right side, the left eye would be cyclophoric and the case would be one of left plus cyclophoria, as the chart indicates (Fig. 35).

Should the red streak dip in toward the patient’s left side, left minus cyclophoria would be designated (Fig. 36).

The patient would instinctively describe, with pointed finger and hand motion, the position of the “dipping” line just as one would describe a spiral staircase. Should this test determine that no cyclophoria exists in either eye, there would be no necessity for further tests.

Some authorities claim that both Maddox rods should be of the same color, so as to more readily assist the patient to fuse the two objects. If the reader so desires, he can readily place a red lens from the trial-case in the forward cell of the instrument.

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.