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Less may be more
For nearly a century ophthalmic surgeons have been intrigued by the possibility of surgical manipulation of the extraocular muscles to improve visual function in patients with congenital nystagmus. In 1906 Colburn described attaching the rectus muscles to the periosteum of the orbital walls in an attempt to reduce the amplitude of nystagmus.1 Widespread acceptance of this procedure did not follow. However, in 1953 Kestenbaum2 and Anderson3 described surgical approaches to correct the abnormal head position adopted by some nystagmus patients. Kestenbaum suggested surgery on all four horizontal rectus muscles (recess-resect procedures in each eye) to move the eyes away from the “null position” of the nystagmus. In contrast, Anderson proposed simply recessing the yoke rectus muscles that move the eyes in the direction of the tonically deviated gaze. In 1954 Goto4 concluded, after electro-oculographic studies in nystagmus patients, that the horizontal rectus muscles that move the eyes away from the tonically deviated gaze are weak and, therefore, should be strengthened by resecting them. Various modifications of these procedures to address the horizontal anomalous head position with nystagmus have been described.5–8 Today most surgeons prefer to operate on all four horizontal rectus muscles (recess-resect in each eye) when there is no significant co-existing strabismus. However, recently there has been revised interest in modifications of the two muscle procedure described by Anderson.9
Anomalous vertical head positions or head tilts either in isolation or in combination with anomalous horizontal head positions may also be seen in association with nystagmus. A number of different approaches have been suggested to treat patients with a combined anomalous head tilt. In the case of co-existing anomalous horizontal and vertical head positions Scott and Kraft6 advocate a simultaneous vertical transposition of the horizontal recti and modified four horizontal muscle procedure (recess-resect in each eye). Others have suggested a two stage approach9,10: (1) reduce the anomalous horizontal head position with a modified two muscle recession (Anderson procedure); (2) postoperatively re-evaluate the head position to see if the vertical head position requires a second procedure. Although several ingenious procedures have been described11–13 to reduce an anomalous head tilt associated with nystagmus there are still limited data on these procedures and the best choice among these techniques is not established. Nevertheless, simultaneous weakening procedures on both the horizontal and vertical muscles to correct a combined horizontal, vertical, and torsional head position associated with nystagmus has been described.14
In this issue of the BJO (p 267) Arroyo-Yllanges and co-workers publish the results of a relatively large series of patients (21) with nystagmus and an anomalous combined head posture. They utilised a modified Anderson procedure with recessions 2 mm behind the equator (in the absence of strabismus). Although the follow up period is relatively short (18.5 months average) the results are promising. Significant improvement in the anomalous head position was recorded in all three planes, except for two patients. It is unclear why addressing only the horizontal face position by recessing just two horizontal rectus muscles should improve the vertical and torsional components of the anomalous head position. Moreover, the corrections were significant up to 20 degrees of correction for both the vertical and torsional components of the anomalous head position. We will be interested to see what longer follow up studies of this procedure document. All previous long term studies of surgery to correct the anomalous head posture associated with congenital nystagmus have reported a disturbingly high reoccurrence rate. Nevertheless, for the moment Arroyo-Yllanges and co-workers have provided provocative data to suggest that in the case of surgery for anomalous head positions associated with congenital nystagmus less may be more.
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Less may be more