PubMed · 15530949
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Derek G Chan, Ian C Francis. Transsphenoidal diplopia.. https://doi.org/10.1016/j.survophthal.2004.08.011
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A transient, decompensated vertical phoria in an individual with infantile nystagmus syndrome (INS) resulted in two images that oscillated vertically-a diplopic oscillopsia. Ocular motor studies during the vertical oscillopsia recreated by vertical prisms, led to the identification of a sub-clinical see-saw nystagmus (SSN), present under the prism-induced diplopic condition. Retrospective analysis of ocular motor recordings made prior to the above episode of vertical diplopia revealed the presence of that same sub-clinical SSN. The SSN had not been detected previously despite extensive observations and recordings of this subject's pendular IN over a period of forty years. Three- dimensional search-coil data from fourteen additional INS subjects (with pendular and jerk waveforms) confirmed the existence of sub-clinical SSN embedded within the clinically detectable horizontal-torsional IN in seven of the fifteen and a sub-clinical, conjugate, vertical component in the remaining eight. Unlike the clinically visible SSN found in achiasma, the cause of this sub-clinical SSN is hypothesized to be due to a failure of the forces of the oblique muscles (responsible for the torsional component of the IN) to balance out the associated forces of the vertical recti; the net result is a small, sub-clinical SSN. Thus, so-called "horizontal" IN is actually a horizontal-torsional oscillation with a secondary, sub-clinical SSN or conjugate vertical component. The suppression of oscillopsia by efference copy in INS appears to be accomplished for each eye individually, even in a binocular individual. However, failure to fuse the two images results in oscillopsia of one of them.
BACKGROUND: Asymmetrical folding of the anterior portion of the superior oblique muscle is a simplified variant of the Harada-Ito procedure that is supposed to selectively correct ocular torsion. PATIENTS AND METHODS: This surgical technique was applied to 22 patients suffering from bilateral acquired IV nerve palsy. Ocular torsion was evaluated with the Harms tangent screen. Pre- and post-operative torsional values were compared. Post-operative follow-up was 12 months. RESULTS: Pre-operatively, mean excyclotropia was 8.8 degrees in primary position and 15.9 degrees in downgaze. Post-operatively, these values decreased to 1.5 degrees and 4.1 degrees, respectively. An enlarged field of binocular single vision, extending beyond 10 degrees inferiorly, was obtained in 17/22 patients. CONCLUSIONS: The selective technique of superior oblique muscle anterior tendon tucking allows one to efficiently correct the ocular torsion induced by acquired bilateral IV nerve palsy.
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