Chapter XIVCYCLODUCTION TEST
Havingdetermined 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 inFig. 38.
Fig. 37—(A. and B.)—Primary position of combined use of both Maddox rods for determining cycloduction test.
Fig. 37—(A. and B.)—Primary position of combined use of both Maddox rods for determining cycloduction test.
Fig. 38Fig. 39Fig. 40Figs. 38-40—Diagram showing position of streaks produced by Maddox rods as they appear to patients in making cycloduction tests.
Fig. 38
Fig. 38
Fig. 39
Fig. 39
Fig. 40
Fig. 40
Figs. 38-40—Diagram showing position of streaks produced by Maddox rods as they appear to patients in making cycloduction tests.
To measure the duction range of the inferior oblique of the right eye, it is merely necessary to slowly rotate the Maddox rod before the right eye upward at its nasal end to the point where the band of light breaks so as to resemble a letter “X”. This gives in degrees the amount of right plus cycloduction, as indicated on the temporal scale, when it will appear to the patient, as shown inFig. 39.
The Maddox rod should then be restored to its original position, with the plus and minus on the 90 degree line of the scale (Fig. 37), and rotated upward at the temporal end until it again takes the form of the letter “X”. (Fig. 40.) The position of the indicator will now denote the amount of right minus cycloduction, or duction range of the rightsuperior oblique muscles. Having determined the duction range of the oblique muscles of the patient’s right eye, both Maddox rods should be placed in original position with rods horizontal and plus and minus sign on 90° of scale, as shown inFig. 37.
The Maddox rod before the left eye is then employed exactly in the same manner as before when the test for the right eye was made. A plus cycloduction of the left eye would be indicated, as shown inFig. 40, while a minus cycloduction of the left eye would appear to the patient, as shown inFig. 39.
By recording a comparison of each eye, as explained, it will be found that the range of duction usually averages five to twenty degrees on either side of the 90 degree line, as indicated on the scale surrounding the Maddox rods.
It will be recalled that cyclophoria was only to be looked for in oblique astigmatic cases. It is frequently possible to correct the patient’s trouble, by changing the axis of the cylinder, before one or both eyes, a minus cycloduction signifying a change of axis towards 180° while a plus toward 90°, according to the amount lacking in full duction power. It is also well to exercise the oblique muscles through a rotation of the Maddox rod before the affected eye, whether it be oneor both that is lacking in full duction power, until the required amount is reached to equal its fellow member.
For a more exhaustive treatise the author suggests a reading of Dr. Savage’s work on the subject.
As previously stated, it often proves of great benefit to employ a muscular exercise where a patient has an existing cyclophoria of either one or both eyes, results derivable through the exercise of the recti muscles having been previously detailed.
To exercise the oblique muscles of the right eye,bothMaddox rods should be placed in the original position employed for making cycloduction test, as previously explained (Fig. 37). This causes the patient to see butoneband or vertical streak (Fig. 38).
The Maddox rod, placed before the right eye, should be slowly rotated inward from ninety degrees to a point on the scale where the single streak of light breaks, when it should again be returned to ninety degrees. This causes a contraction and relaxation of the muscles in the form of an exercise and should be repeated ten times—about fiveminutes each day. By employing the Maddox rod before the left eye in precisely the same manner, its oblique muscles will be exercised.
To determine whether or not this form of exercise is beneficial to the patient, the weekly cycloduction test, as previously described, should be made and compared with the original findings.
Ski-optometer Model 235A Compact Phorometer and Trial-Frame.For Testing and Correcting Muscular Imbalance—Providing a Comfortable Form of Trial-Frame.
Ski-optometer Model 235A Compact Phorometer and Trial-Frame.For Testing and Correcting Muscular Imbalance—Providing a Comfortable Form of Trial-Frame.
Ski-optometer Model 235
A Compact Phorometer and Trial-Frame.
For Testing and Correcting Muscular Imbalance—Providing a Comfortable Form of Trial-Frame.