Does Decreased Static Ocular Counter Rolling Account for Bielschowsky Head Tilt Test in Unilateral Superior Oblique Palsy?

Abstract

PURPOSE. To understand the relationship of static ocular counter rolling (s-OCR) and clinical manifestations in acquired unilateral superior oblique palsy subjects during the Bielschowsky head tilt test.METHODS. Nineteen subjects that were diagnosed with acquired unilateral superior oblique palsy were included. Fundus photographs were obtained at different head tilt angles to evaluate static ocular counter rolling using a fundus camera with a cervical range of motion device. Using a graphics editing program, we calculated s-OCR from fundus photography.RESULTS. The incycloductional s-OCR (OCR-I) in the paretic eye was significantly smaller than the OCR-I in the fellow eye (P ¼ 0.02, <0.001, 0.002 for 108, 208, and 308, respectively, paired t-tests). In contrast, the excycloductional s-OCR (OCR-E) showed no significant difference between the paretic eye and the fellow eye for all angles. There was a significantly positive correlation between the amplitude of OCR-I in the paretic eye and the degree of hypertropia on ipsilesional head tilt (q ¼ 0.612, 0.679, 0.474, P ¼ 0.02, 0.002, 0.07 for 108, 208, and 308 respectively, Spearman's correlation). The amplitude of OCR-I in the paretic eye also showed a positive correlation with head tilt test difference, which is the degree of hyperdeviation difference between ipsilesional and contralesional head tilts (q ¼ 0.445, 0.694, 0.579, P ¼ 0.09, 0.002, 0.024 for 108, 208, and 308 respectively, Spearman's correlation).CONCLUSIONS. In unilateral SOP, OCR-I in the paretic eye was smaller than that in the fellow eye, and this was positively associated with the degree of hypertropia during ipsilesional head tilting, as well as the head tilt test difference.Keywords: superior oblique palsy, static ocular counter rolling, Bielschowsky head tilt test, cervical range of motion device O cular counter rolling (OCR) is a partially compensatory torsional eye movement that occurs when the head is tilted toward the shoulder.1 Static OCR (s-OCR) is mediated by an otolith-ocular reflex in response to a gravitational direction change, while dynamic OCR is mediated by the semicircular canal-ocular reflex in response to torsional angular acceleration during active head movement.2 The s-OCR is thought to be the biomechanic basis of the Bielschowsky head-tilt test (BHTT). [3][4][5][6] Clinically, superior oblique palsy (SOP) subjects exhibit positive BHTT, which means the paretic eye shows greater hypertropia during head tilt to the ipsilesional side compared to the contralesional shoulder. According to traditional s-OCR theory, when the head is tilted to the left shoulder, the intorters (superior oblique [SO] and superior rectus [SR]) of the left eye and the extorters (inferior oblique and inferior rectus) of the right eye are activated while extorters of the left eye and intorters of the right eye are inhibited. In left SOP, downward torque of the superior oblique is absent, so unopposed upward movement by the activated superior rectus is thought to contribute to hypertropia of the left eye du...

Clinical characteristics according to the laterality of ocular torsion in unilateral superior oblique palsy

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Comparison of ocular torsion between congenital and acquired unilateral superior oblique palsy

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Measurement of ocular counter-roll using iris images during binocular fixation and head tilt

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